A question for the Transmission experts

[Trevor]

Originally Posted by NiftySVX

So the million dollar question is why do I have a near constant 2.15v at the connector for the transmission, when I have correct voltage outputs for the resistor and for the solenoid at the TCU? And, is this is what is causing my problem?

Having received your PM covering your query as above, I have sent you a lengthy reply. The non technical moderators here tend to take correcting or correct information as a form of baiting. What is more this type of thread becomes a tedious mess.

[NiftySVX]

The Plot thickens...

I have corrected a minor wiring problem that was causing inaccurate readings before. I am now able to observe a change in voltage from 2.5v at fully closed throttle to .1 volt at wide open. Is this normal? I put up another thread asking someone to backprobe their dropping resistor with it plugged in at the green/yellow wire but no one has done it yet. Perhaps someone could do me this favor? If it is normal to see 2.5v at closed throttle then I am going to go ahead and condemn the solenoid, which will be the point at which I involve level 10.

[Trevor]

I have informed you in this regard, within my last quite extensive PM.

[NiftySVX]

Ok here's what I've found out. There is a signal going to the solenoid, I scoped it and feel like, if the control system is operating properly, I now have a pretty good idea of how this thing works.

At idle, the solenoid is held on to bleed pressure to a minimum value. I observed a constant voltage at closed throttle. As soon as the throttle is moved off idle, the solenoid starts pulsing and allowing a higher flow, with the on time being less and less as you approach wide open.

The dropping resistor applies another wave who's crests are in between that of the primary signal. This is what is meant by the statement "the dropping resistor provides another signal that ensures that the solenoid is never fully off"

If there is an open detected in the circuit, the solenoid is switched on, (constant 12v signal) which according to the manual gives max line. This is confusing because there is already max line at the trans with the connector unplugged and it is most certainly not getting any voltage. I don't really get that. The manual says the solenoid is switched off, implying that it is normally on.

This all seems to be opposite of the current thoughts on how this thing works

[Trevor]

Originally Posted by NiftySVX

Ok here's what I've found out. There is a signal going to the solenoid, I scoped it and feel like, if the control system is operating properly, I now have a pretty good idea of how this thing works.

At idle, the solenoid is held on to bleed pressure to a minimum value. I observed a constant voltage at closed throttle. As soon as the throttle is moved off idle, the solenoid starts pulsing and allowing a higher flow, with the on time being less and less as you approach wide open.

The dropping resistor applies another wave who's crests are in between that of the primary signal. This is what is meant by the statement "the dropping resistor provides another signal that ensures that the solenoid is never fully off"

If there is an open detected in the circuit, the solenoid is switched on, (constant 12v signal) which according to the manual gives max line. This is confusing because there is already max line at the trans with the connector unplugged and it is most certainly not getting any voltage. I don't really get that. The manual says the solenoid is switched off, implying that it is normally on.

This all seems to be opposite of the current thoughts on how this thing works

This is in fact not opposite to correct current thoughts. All of this shows that my data, as posted for a very long time on all of this, is correct.

The interpretation of the arrangement as above, has been confused because the solenoid valve is normally closed, i.e. when the solenoid is not energised the valve is closed. A closed valve results in maximum pressure, because the valve controls a bleed, rather than the line pressure as such.

The relevant data:-

SVX TRANSMISSION SOLENOIDS

DUTY SOLENOID VALVE "A".

This is a pulse width modulated duty solenoid valve, ( Sometimes known as a pulsoid). The device is incorporated in the SVX transmission control system in order to adjust line pressure in the following manner :-
The fluid line is provided with a bleed or bypass via an on/off device, in the form of an electrically operated valve. This solenoid valve is opened and closed repeatedly, in a rhythmical manner by a control current which is turned on and off by the transmission control unit, (TCU) at a constant very fast rate, i.e. at 50 cycles per second. The valve is a normally closed device, and so as to be fail safe, remains closed in the event of the loss off a control current.
After passing through this modulated solenoid valve, the continually interrupted pressure is in the form of a pulsed flow. When the peaks level off with the troughs, there is a resulting overall steady reduced pressure. The level of this pressure is adjusted by varying the on/off intervals and the number of pulses per second is kept constant. The adjusted output pressure is therefore delivered as a rapidly fluctuating stream.

The system incorporates an expansion chamber as a smoothing element. This device is usually in the form of a cylinder and piston or diaphragm, backed by a coil spring. In the SVX system the component is described as a Pressure Modifier Accumulator. The high pressure peaks in the system press the piston outwards and become rounded off, while the low pres-sure troughs are filled in as a result of the piston moving inwards under spring pressure. The end result is a relatively smooth level of pressure, such that controlled devices are not materially affected, particularly due to having substantial reciprocating weight and resistance to sudden move-ment..
An increase in the volume of fluid controlled, is achieved by transferring the solenoid regulated pressure, to a pressure modifier valve and regula-tor valve, thus increasing the available hydraulic power.
It should be clear that by “chopping” the fluid supply in an adjustable way, pressure control is achieved economically using a simple poppet type solenoid valve, with few mechanical or electrical complications. However the valve remains in a continuous cycling mode, which imposes rather arduous mechanical stresses on this component.


THE DROPPING RESISTOR CIRCUIT.

It will be immediately apparent that the sudden on off pulse width modu-lated duty to which solenoid valve “A” is subject, tends to cause what could be called a hammering of the valve seat, even though this is largely reduced/damped by the controlled fluid flow.

The dropping resistor introduces a second series of current pulses applied in parallel with the control signal. These pulses are applied across the off cycles, so as to check the travel of the armature as it reaches the closed position, thus reducing both shock and noise. These secondary parallel signals in effect, mean that during the closing period the voltage does not fall completely to zero so as to reduce the closing shock.

This second series of pulses must be at a lesser level than the control signal, hence the dropping resistor. A resistor with a high current rating is required, which could not be mounted within the TCU enclosure.

It will be appreciated that increasing the resistance in the circuit, or opening the circuit by omitting the dropping resistor, has two outcomes. Firstly the voltage during the closed time becomes zero with an increase in the effect, thus increasing the line pressure and making shifts more abrupt. Secondly, as an undesirable issue, shock loads applied to the valve are increased.

It is a recognized fact that the line pressure control solenoid is usually the first to fail, due to having to fulfill by far the most arduous duty. Failure is usually mechanical resulting in the valve seat not closing properly and as a result line pressure is markedly reduced. The end result can be drastic, especially in respect of transmission friction surfaces.

The resistor should measure between 9 and 15 ohms to be within specifica-tions and is usually close to 12 ohms.


SOLENOID "C".

Also a pulse width modulated solenoid valve this device is arranged to adjust control pressure to the centre differential, or alternatively clutch actuating mechanism. According to model, solenoid “C” operates along the same lines as solenoid “A” and therefore cycles continuously.
However the duty is in no way as arduous as that involving constant control of line pressure and no parallel secondary circuit is incorporated.

In respect of the JDM box with VTD clutch, a signal providing the maxi-mum energised time and current to a normally open solenoid valve “C”, will increase transfer control pressure by closing a bleed. This causes the LSD clutch to be engaged, resulting in front rear drive virtual lock up. This can proven by inserting the control fuse.

Electrical failure of solenoid valve “C”, will result in the clutch not becom-ing engaged and therefore drive in accordance with the fixed mechanical ratio of the differential, i.e. front 36.4%, rear 63.6%.

The US arrangement incorporates a normally closed solenoid “C”, so that a similar control signal, reduces control pressure by opening the solenoid and creating a bleed. Consequently the clutch does not operate and there is no rear wheel drive.

Electrical failure of solenoid valve “C”, will result in the clutch operating and front rear binding.

These alternative arrangements in respect of the solenoid valve configuration, prevents the need for alterations in respect of the mechanical hydraulic components used in the two systems.

[NiftySVX]

The last part was what I meant about contradicting. I don't get why the tcu would output a 12v signal across the wire when it is unplugged. This would turn the solenoid ON, effectively reducing line pressure to the minimum value, which appears to be the 70 psi I am observing. Also, why does the solenoid always have a base voltage, like when it is not switched on, it's not at 0v but actually at about 1 or so?

[Trevor]

Originally Posted by NiftySVX

The last part was what I meant about contradicting. I don't get why the tcu would output a 12v signal across the wire when it is unplugged. This would turn the solenoid ON, effectively reducing line pressure to the minimum value, which appears to be the 70 psi I am observing.

When you say “with the connector unplugged”, what exactly has been unplugged? If you are referring to the resistor circuit, when disconnected, this still leaves the main control circuit complete. At idle this signal will be present to open the valve for fully reduce pressure.

Also, why does the solenoid always have a base voltage, like when it is not switched on, it's not at 0v but actually at about 1 or so?

The solenoid requires a minimum of 9 volts to operate and drops out at 3 volts. Both figures being subject to tolerance. Therefore one or so volts, will have no affect on the valve, which is held closed by a spring.

You have confirmed that your system is at fault, therefore in any event, it can not be accepted as typical.

[NiftySVX]

Connector T2 at the transmission, disconnecting the solenoid pack from the TCU. What tells you that the control system is faulty?

[Trevor]

Originally Posted by NiftySVX

Connector T2 at the transmission, disconnecting the solenoid pack from the TCU.

I am loath to be critical, but at this point patience is wearing thin.

I have advised you in great detail, here as well as by PM. Several others have made suggestions regarding items you should check. At no point have you positively confirmed that these tests have been completed. Those trying to assist you, are therefore completely unsure of what is what. Your advice most often is not definitive and requires further query before becoming of value.

You now appear to obtusely advise that you are measuring 12 volts of signal directed to solenoid “A”, i.e. “I don't get why the tcu would output a 12v signal across the wire when it is unplugged. Connector T2 at the transmission, disconnecting the solenoid pack from the TCU.”

This would appear to be very much at odds with your previous statements as follows:-

Post #1 ---
With resistor: 75 psi at idle in D Short jump then settles back to 75 psi at stall
Without resistor: 270 at idle 75 at stall??!!?

Post #6
Unplugging the connector at the trans makes a constant 270 line.
with the dropping resistor unplugged, line is at 270 with throttle closed. As soon as you move the tps it backs down to 75.

Post #7
Oh and what i meant by short jump to 270 then settles at stall is that at stall speed it will not maintain 270, only for a short while, meaning the pressure drops back to 75 with the converter still at stall

Post #20
The TPS sensor did not fix the transmission. I am now going to attempt to read the duty ratio directly at the transmission connector for solenoid A.
I do have a scope, and my fluke will read Hz.

Post #24
the Green wire with a yellow tracer that connects directly to the solenoid according to the diagram.
the green/yellow wire from the dropping resistor splices with the green/yellow that runs between the TCU and the connector at the transmission.
I can measure the voltage at the transmission connector across the black ground wire and the green/yellow solenoid A wire. I get a reading that ranges from 2.16V to 2.14
I am unsure why I have a constant 2.15 volts at the connector for the transmission.

Post #30

So the million dollar question is why do I have a near constant 2.15v at the connector for the transmission,

Post #32

I am now able to observe a change in voltage from 2.5v at fully closed throttle to .1 volt at wide open.

#36
I don't get why the tcu would output a 12v signal across the wire when it is unplugged.
Also, why does the solenoid always have a base voltage, like when it is not switched on, it's not at 0v but actually at about 1 or so?

(1) Are you measuring twelve volts using a meter or a scope which you have calibrated? It is noted that you have one.
(2) Is 12 volts DC indicated or the peak of PWM signal?
(3) Is 12v volts on line when the connector is plugged in and the solenoid is therefore in circuit so as to form a load?

What tells you that the control system is faulty?

I am given to assume that the system is faulty, because your have advised that you have a control system problem, which is very the reason for this thread. The control system comprises the TCU, solenoid “A” and associated mechanical valves.

Please, test the solenoid by applying battery voltage for a short period, as I have previously suggested, after disconnecting the main transmission connector. You now confirm that you have access to it. With no volts applied you should be able to achieve maximum pressure. With battery volts (say 12 volts+), minimum pressure. Off/On several times in an effort to locate something intermittent.

Please then exactly confirm the result and we will have at least one logical fact to go by. Most importantly your major issue, as to whether Level Ten is at fault, will be solved.

[NiftySVX]

I apologize for the somewhat illogical layout of my posts. This is due, to the most part, that I am forced to work on the car at random times, usually only for a few minutes do to the fact that I have to prioritize customer work.

I am going to organize a post here that shows specific, repeatable checks I have performed shown in bold to make it easy to follow my diagnostic checks.

First, I confirmed that there was a line pressure abnormality by checking line pressure.

I first tested and confirmed an abnormality in the TPS sensor which I replaced as a first step in diagnosis. I had known for some time that My TPS sensor had a dead spot in it which made the car have a hesitation.

I next discovered the following:

Without disconnecting any components, Line pressure remains at a constant pressure of approx. 75 psi. This reading was taken while in 'D'. Line pressure does not change from 75 under any circumstances, including engine speed, vehicle speed, throttle position.

With the Dropping resistor unplugged, Line pressure is at maximum at idle. When the throttle is moved off idle, say to about 10% open, the pressure immediatly falls back to the 75 psi reading and stays there for the rest of the throttle travel.

At this point, I got out the voltmeter, because I hypothesized that the solenoid was being switched on at the moment the pressure went back to 75. (this was proved correct in the next step)

With the voltmeter, I found the following.

At First, I could not get the reading to change from 2.5 volts. I later found out that this was due to a ground problem in the battery negative cable, which I corrected. Once corrected, I was able to observe the following by backprobing the T2 connector (that is, a small, needle like terminal is inserted into the back of the connector to make contact with a particular pin in that connector so it is possible to observe what is going on in the circuit with all connectors connected and the system in operation)

With dropping resistor connected, Voltage at the T2 connector, pin 7 (solenoid A wire) ranged from about 2.5v at closed throttle to 0.1v at wide open throttle. (remember, with the system in this state line pressure is a constant 75)

Without the dropping resistor connected, voltage at pin 7 of connector T2 is 0v with the throttle closed, while line pressure is at maximum pump output. When the throttle is rotated to about 10%, voltage becomes present in the circuit at the exact moment line pressure drops back to 75. (As I had anticipated)

My next check was of the inhibitor switch circuit as I was advised by a post in this thread. It was within specifications.

While waiting on the picoscope I had requested from a collegue to become available, I performed each check according to the pages in the repair manual for trouble code 11 that indicates solenoid A failure. (even though this code is not output) All of these values were within specifications given in the factory service manual. This included resistance checks of the harness between the TCU and the Dropping resistor, and between the dropping resistor and the T2 connector.

I next, much to my disdain, made a copy of the TCU pinout pages in the service manual and got out a highlighter. I checked each pin of the TCU as listed in the pinout diagram and found that each was within specification

At this point I the pico scope had arrived, and I set up both pins of the dropping resistor and pin 7 of the T2 connector for backprobing with the picoscope. I was eager to examine this because pat of level ten claimed that the solenoid is not operated on a duty cycle but rather a continous, vairable voltage. He claimed that I should not observe a waveform. On the contrary, I did observe a waveform and it was at this point that I really was able to "look up the skirt" of the circuit, so to speak. Findings are as follows:

At closed throttle with Ignition on, engine off, resistor and all connections in tact there is always a voltage present across the T2 pin 7. I forget its exact value but if memory serves it is somewhere around 1-2v. Interestingly, there is no duty cycle at closed throttle, only a constant "base" voltage. When throttle is opened off idle, to about the magic point at which things have always appeared to happen in this circuit, the cycling begins. This is a 12v cycle, which cycles from +12 to -12v. The scope has a secondary wave present in it, which crests inbetween at a much lower intensity which is the result of the dropping resistor. This secondary wave dissapears upon unplugging the resistor, along with the base voltage observed, but does not change the primary wave The waveform is widest at idle, and becomes more narrow at wide open, but not by much. The difference in the "on" time as observed in the waveform is very small, almost insignificant.

From these observations with the scope, I am able to infer the following:

The base line voltage is enough to swtich the solenoid on to some degree, which is why line pressure is high at idle with the resistor removed. The solenoid does not cycle at idle, and is told by the TCU to dump so minimum line is achieved. Upon throttle increase, the solenoid starts to cycle, and continues to do so at all other times. At this point I was confused. Was the solenoid normally open or is it normally closed? What is this waveform telling me?

I then probed the green/yellow wire at the dropping resistor, which is for all intents and purposes the identical signal found at T2 pin 7, so i could observe what the TCU would do when it went into fail safe, as I disconnected the T2 connector which triggers(among others) a code 11, as there is now an open circuit to the solenoid. Contrary to what I expected, the TCU outputs a steady 12v signal across the green/yellow wire when it detects a solenoid A failure. Now remember, according to the FSM, in the event of a solenoid a failure, the solenid "is turned off for maximum line pressure". This implies that, in order for MAX line pressure, the solenoid must be energized. This is contrary to what has been said here, and is contrary to what I have observed. The Solenoid, when disconnected electrically, gives full line pressure. If the TCU outputs a signal for full on, then the solenoid, when disconnected, should give minimum line pressure. This seems to support the theory that the solenoid is of the normally open type and that it closes to seal off and build pressure.

At this point, I contacted Level ten, and asked for advice. I was told that I would be sent a solenoid, but only as a diagnosis step, as he is 99% sure that this is a control system problem. He also stated the part about the solenoid being an on/off type and that observing a duty cycle was abnormal.

As the solenoid is currently on its way to me, I am faced with a dilemma. How can I be sure that this solenoid is any better than the one I have, because it appears that it is a possibility that the solenoid is not malfunctioning but actually of the wrong design

This is where I am at with this situation, and I am considering pulling a solenoid pack from another 4EAT and trying it first, in place of the new one currently on its way.

[Trevor]

Originally Posted by NiftySVX

I apologize for the somewhat illogical layout of my posts. This is due, to the most part, that I am forced to work on the car at random times, usually only for a few minutes do to the fact that I have to prioritize customer work.

I am going to organize a post here that shows specific, repeatable checks I have performed shown in bold to make it easy to follow my diagnostic checks.

First, I confirmed that there was a line pressure abnormality by checking line pressure.

I first tested and confirmed an abnormality in the TPS sensor which I replaced as a first step in diagnosis. I had known for some time that My TPS sensor had a dead spot in it which made the car have a hesitation.

N.B. When replaced was the TPS correctly set at 0.5 volts, at a confirmed exactly closed throttle? You confirm that at a later stage a battery ground faulty was located. This may have affected any voltage reading you may have worked on.

This adjustment is particularly important in view of that which occurs immediately the throttle is opened. Please check this adjustment again, even though you may be confident that it is OK.

I next discovered the following:

Without disconnecting any components, Line pressure remains at a constant pressure of approx. 75 psi. This reading was taken while in 'D'. Line pressure does not change from 75 under any circumstances, including engine speed, vehicle speed, throttle position.

With the Dropping resistor unplugged, Line pressure is at maximum at idle. When the throttle is moved off idle, say to about 10% open, the pressure immediatly falls back to the 75 psi reading and stays there for the rest of the throttle travel.

Refer to note on TPS adjustment above.

At this point, I got out the voltmeter, because I hypothesized that the solenoid was being switched on at the moment the pressure went back to 75. (this was proved correct in the next step)

With the voltmeter, I found the following.

At First, I could not get the reading to change from 2.5 volts. I later found out that this was due to a ground problem in the battery negative cable, which I corrected. Once corrected, I was able to observe the following by backprobing the T2 connector (that is, a small, needle like terminal is inserted into the back of the connector to make contact with a particular pin in that connector so it is possible to observe what is going on in the circuit with all connectors connected and the system in operation)

With dropping resistor connected, Voltage at the T2 connector, pin 7 (solenoid A wire) ranged from about 2.5v at closed throttle to 0.1v at wide open throttle. (remember, with the system in this state line pressure is a constant 75)

Without the dropping resistor connected, voltage at pin 7 of connector T2 is 0v with the throttle closed, while line pressure is at maximum pump output. When the throttle is rotated to about 10%, voltage becomes present in the circuit at the exact moment line pressure drops back to 75. (As I had anticipated)

OK. At this point the normally closed solenoid valve will open the bleed and drop the pressure.

My next check was of the inhibitor switch circuit as I was advised by a post in this thread. It was within specifications.

While waiting on the picoscope I had requested from a collegue to become available, I performed each check according to the pages in the repair manual for trouble code 11 that indicates solenoid A failure. (even though this code is not output) All of these values were within specifications given in the factory service manual. This included resistance checks of the harness between the TCU and the Dropping resistor, and between the dropping resistor and the T2 connector.

These checks will not indicate a mechanical fault or an obstruction in the valve. You MUST carry out the check I have suggested, otherwise you are groping in the dark.

I next, much to my disdain, made a copy of the TCU pinout pages in the service manual and got out a highlighter. I checked each pin of the TCU as listed in the pinout diagram and found that each was within specification

At this point I the pico scope had arrived, and I set up both pins of the dropping resistor and pin 7 of the T2 connector for backprobing with the picoscope. I was eager to examine this because pat of level ten claimed that the solenoid is not operated on a duty cycle but rather a continous, vairable voltage. He claimed that I should not observe a waveform. On the contrary, I did observe a waveform and it was at this point that I really was able to "look up the skirt" of the circuit, so to speak.

Surely you must have not exactly understood Pat. There is evidence within a thread that I contacted him some time ago, together with his reply, which confirms a modulated signal to a N/C solenoid valve.

Findings are as follows:

At closed throttle with Ignition on, engine off, resistor and all connections in tact there is always a voltage present across the T2 pin 7. I forget its exact value but if memory serves it is somewhere around 1-2v. Interestingly, there is no duty cycle at closed throttle, only a constant "base" voltage. When throttle is opened off idle, to about the magic point at which things have always appeared to happen in this circuit, the cycling begins. This is a 12v cycle, which cycles from +12 to -12v. The scope has a secondary wave present in it, which crests inbetween at a much lower intensity which is the result of the dropping resistor. This secondary wave dissapears upon unplugging the resistor, along with the base voltage observed, but does not change the primary wave The waveform is widest at idle, and becomes more narrow at wide open, but not by much. The difference in the "on" time as observed in the waveform is very small, almost insignificant.

From these observations with the scope, I am able to infer the following:

The base line voltage is enough to swtich the solenoid on to some degree, which is why line pressure is high at idle with the resistor removed. The solenoid does not cycle at idle, and is told by the TCU to dump so minimum line is achieved. Upon throttle increase, the solenoid starts to cycle, and continues to do so at all other times. At this point I was confused. Was the solenoid normally open or is it normally closed? What is this waveform telling me?

The solenoid is normally closed and opens during the on time of each pulse, subject to the overriding softening signal via the resistor circuit, as I have detailed.

I then probed the green/yellow wire at the dropping resistor, which is for all intents and purposes the identical signal found at T2 pin 7, so i could observe what the TCU would do when it went into fail safe, as I disconnected the T2 connector which triggers(among others) a code 11, as there is now an open circuit to the solenoid. Contrary to what I expected, the TCU outputs a steady 12v signal across the green/yellow wire when it detects a solenoid A failure. Now remember, according to the FSM, in the event of a solenoid a failure, the solenid "is turned off for maximum line pressure". This implies that, in order for MAX line pressure, the solenoid must be energized. This is contrary to what has been said here, and is contrary to what I have observed. The Solenoid, when disconnected electrically, gives full line pressure. If the TCU outputs a signal for full on, then the solenoid, when disconnected, should give minimum line pressure. This seems to support the theory that the solenoid is of the normally open type and that it closes to seal off and build pressure.

Think again. The solenoid valve controls a pressure bleed. Energised the bleed is open. With zero or less than say 2 volts, the valve is closed, resulting in full pressure.

Your statement:- "The Solenoid, when disconnected electrically, gives full line pressure." is therefore logical correct and as would be expected.

At this point, I contacted Level ten, and asked for advice. I was told that I would be sent a solenoid, but only as a diagnosis step, as he is 99% sure that this is a control system problem. He also stated the part about the solenoid being an on/off type and that observing a duty cycle was abnormal.

As the solenoid is currently on its way to me, I am faced with a dilemma. How can I be sure that this solenoid is any better than the one I have, because it appears that it is a possibility that the solenoid is not malfunctioning but actually of the wrong design

This is where I am at with this situation, and I am considering pulling a solenoid pack from another 4EAT and trying it first, in place of the new one currently on its way.

Please, please carry out the simple test I have suggested and you will know whether or not to suspect the solenoid.

P.S. Herewith copy of e-mails with Pat of Level Ten:-

E-mail correspondence with LEVEL TEN , Hamburg, New Jersey, USA, Specialists in Performance Transmission Systems.
Dated, 16 - 17 Dec. 2006.


> -----Original Message-----
> From: Trevor R. Sheffield [mailto:trevshef@xtra.co.nz]
> Sent: Saturday, December 16, 2006 5:12 AM
> To: support@levelten.com
> Subject: 4EAT
>
> You are acknowledged experts in respect of automotive transmissions and I therefore am approaching you for a favour in respect of kindly advice.
>
> I am involved with a Subaru Car Club and am writing up information covering the often used 4EAT transmission system. There is a point which is not made exactly clear within information I have been able to obtain, and there is some debate regarding the subject.
>
> It is my understanding that the PWM solenoid valves incorporated for line pressure, center clutch and lock up control, are all normally closed devices. i.e. When the solenoid is not energised fluid pressure is restricted/shut off. When energised the valve opens and passes fluid to a drain.
>
> It would be greatly appreciated it if you could confirm that I am correct, or if not the actual configuration applicable.
>
> Special thanks in anticipation,
>
> Trevor R. Sheffield,
> 16A Seaside Ave., Waterview,
> Auckland,1026, New Zealand.
> PHONE-- 00 64 09 8208553
> trevshef@xtra.co.nz
>

> From: Level Ten <info@levelten.com>
> Date: Sat, 16 Dec 2006 06:03:01 -0500
> To: "'Trevor R. Sheffield'" <trevshef@xtra.co.nz>
> Subject: RE: 4EAT
>
> To Trevor
>
> Great question? You are correct. When not energized they are restricted/shut off.
>
> Pat


Special thanks Pat,

Your so very prompt reply is very much appreciated.

Compliments of the season, Trevor.


Pat,

As you have been so very helpful could you please confirm something else for me i.e. That the normally closed PWM solenoid valves move in synchronism with their respective modulated signal.
There has been a suggestion made that they are held open and stationery at variable increments, in order to control pressure. Weird I know, but an argument I must put to rest.

I hope I am not being a nuisance. Again thanks, Trevor.


To Trevor

The pwm solenoid is pulsed from 0% - 100%.
If you have any more question feel free to ask.

Pat

[longassname]

I have pretty detailed information on the regulation of line pressure from the fluid circuits involved to photos of my tektronix oscilloscope simultaneously monitoring the tcu output to both the resistor circuit and main duty solenoid A duty cycle.

If you two can promise not to beat eachother up over the points where the other is wrong and not harbor any animosity towards me for posting the correct information and actually mean it then I will do so.

[Trevor]

Greetings Michael,

I for one have not made accusations of right or wrong, neither has the other party. All has been a matter of sorting out an obscure problem and the difficult of clearly putting same into words. A straight exchange of information does not constitute animosity, unless read out of context.

It is only right and fair that any information posted should stand up to scrutiny. If your information is truly correct, what is the problem? Why do you expect animosity? In the event that accuracy depends entirely on your opinion regarding the facts presented and there could be alternative views, you must in honesty accept debate.

I have prepared a switched tap in wiring set up, to operate an oscilloscope in the car while it is being driven. Unfortunately I am not able to drive at the moment, so that a delay is inevitable. Surely both our read outs should be complimentary, thus adding data within an interesting project, to the good of all.

Cheers, Trevor.

[NiftySVX]

Originally Posted by longassname

I have pretty detailed information on the regulation of line pressure from the fluid circuits involved to photos of my tektronix oscilloscope simultaneously monitoring the tcu output to both the resistor circuit and main duty solenoid A duty cycle.

If you two can promise not to beat eachother up over the points where the other is wrong and not harbor any animosity towards me for posting the correct information and actually mean it then I will do so.

I have litte interest in ego or pride on this matter, I don't know how it works, I just need the info so I can make this trans work.

And Trevor, I just now tested the solenoid from the battery giving it a 12v signal and it goes down to 75 psi. As I have suspected for some time, something is causing this solenoid to stay on and not cycle.

[longassname]

I know. I just know the history between you two and it doesn't feel like there is anything to gain by sharing the information that will settle the debate. I feel like if I do instead of each of you feeling somewhat vindicated as being right on the points you are right on you will both feel somehow slighted for being shown wrong on the points you are wrong on.

Originally Posted by Trevor

Greetings Michael,

I for one have not made accusations of right or wrong, neither has the other party. All has been a matter of sorting out an obscure problem and the difficult of clearly putting same into words. A straight exchange of information does not constitute animosity, unless read out of context.

It is only right and fair that any information posted should stand up to scrutiny. If your information is truly correct, what is the problem? Why do you expect animosity? In the event that accuracy depends entirely on your opinion regarding the facts presented and there could be alternative views, you must in honesty accept debate.

I have prepared a switched tap in wiring set up, to operate an oscilloscope in the car while it is being driven. Unfortunately I am not able to drive at the moment, so that a delay is inevitable. Surely both our read outs should be complimentary, thus adding data within an interesting project, to the good of all.

Cheers, Trevor.