Memory dump of ECU

[TomsSVX]

I can see the duty cycle using the actual select monitor... if there is anything I can help with in this regard let me know... As for the AWD split. In US models the lower the duty cycle to the sol. C the closer one is to a 50/50 torque split. the higher the duty cycle, the less power is transfered to the rear wheels. That is why when the FWD fuse is installed, it provide a 12v constant to the sol C which allows the transfer clutches to lay laxed... Let me know if this is confusing

Tom

[b3lha]

Originally Posted by Calum

Some multi-meters can actually. Fluke has made models that can for years, and some of the cheap chinese meters picked up this feature (lucky for us cheapskates).

http://www.mouser.com/search/Product...U97kdFdw%3d%3d

For $30 it might be worth picking one up just to test your theories.

I'm not surprised that modern multimeters can do this. My comment was more aimed at the service manual that suggests measuring the voltage of the TCU pin that drives the solenoid.

I bought an old oscilloscope recently, which is probably the best tool for the job. But I suppose there is a chance that my old analog "AVO" meter might actually read a voltage proportional to the duty cycle.

In any case, I have no need to measure the duty cycles electrically. I have figured out how the TCU generates them and can read them from the memory through the select monitor interface.

[b3lha]

Originally Posted by TomsSVX

I can see the duty cycle using the actual select monitor... if there is anything I can help with in this regard let me know... As for the AWD split. In US models the lower the duty cycle to the sol. C the closer one is to a 50/50 torque split. the higher the duty cycle, the less power is transfered to the rear wheels. That is why when the FWD fuse is installed, it provide a 12v constant to the sol C which allows the transfer clutches to lay laxed... Let me know if this is confusing

Tom

OK. So we've established that 0% duty is F50:R50 and 100% duty is F100:R0. What percentages equate to 60:40, 70:30, 80:20 and 90:10.

Next time you get the select monitor out to play with it, I'd be interested to know the answer.

It doesn't have to be those exact splits, just a range of values, split versus duty to plot on a graph and join up the dots.

[TomsSVX]

I will test it out when i take this stock trannied 96 out for a test drive later on...

Tom

Originally Posted by b3lha

OK. So we've established that 0% duty is F50:R50 and 100% duty is F100:R0. What percentages equate to 60:40, 70:30, 80:20 and 90:10.

Next time you get the select monitor out to play with it, I'd be interested to know the answer.

It doesn't have to be those exact splits, just a range of values, split versus duty to plot on a graph and join up the dots.

[Trevor]

Originally Posted by b3lha

That's what doesn't make sense.

The quote from the service manual and the results of Nomake's experiment suggest to me that a high duty cycle is FWD and a low duty cycle is 50:50. Furthermore I was under the impression that "no FWD" (ie. RWD only) is an impossibility on a USDM tranmission.

Please explain.

Phil, sincere apologies.

In the past I have always used “FWD” as meaning Four Wheel Drive, which in this instance has lead to what amounts to an error. Please read as follows:-

When the normally closed solenoid is energised via a high duty cycle the valve will open and control pressure will be bled off. Reduced pressure will result in the clutch opening and therefore no Four Wheel Drive, i.e. only Front Wheel Drive.

Again sorry for the confusion. Trevor.

[Nomake Wan]

I know that math isn't always the order of the day, but I did some anyway, assuming that the TCU uses a linear plot for torque split. So here's the math...

We'll take the SolC duty cycle and call it 'x'. 'x' can go from 5 to 95. For simplicity's sake, we'll have 'y' represent the rear torque split, which can go from 50 to 0. So when x=5, y=50. And when x=95, y=0. Assuming this is a linear plot, that gives us the equation

y = (5/9)x - (25/9)

Now, if we then assume x=65, which is about what my car registers on SolC during normal driving, this gives us a result of y=33.3. So the torque split would be 67/33, approximately.

If you then think about how the JDM VTD box advertises a torque split of 35/65, it starts to sound rather interesting. Anyway, that's just some math. Whether it means anything or not is up to the hands-on mechanical guys.

[TomsSVX]

I know this is kinda off topic but the VTD gearboxes are mechanically VERY different from our own... Just lets keep it to the transfer clutch boxes we all have to deal with, those lucky VTD suckers can suck eggs

Tom

[TomsSVX]

also good to remember, the TCu is not going to allow either a 50/50 split nor a 100/0 split under normal driving. Binding is no good and FWD gives you nothing on a positive side. I will go out and do some testing now to see what we find.

Tom

[TomsSVX]

ok Here is what we have...

At idle in Park or Neutral: 95%

Idle in D or R: 70%

Coasting in D: 70%

1/4 throttle accel: 55%

1/2 throttle accel: 35%

3/4 throttle accel: 33% but quickly begins to rise up to 35 and further up as you accelerate.

Full throttle accel: 5-15% and quicklu rises to 35% and further up as you accelerate.

Now as you do your match remember 0% is 50/50 and 100% is Front Wheel Drive only

Now, unfortunately it is a real select monitor so I cannot see more than one parameter at a time. I wish I could see this and plot it in relation to throttle position to get a more accurate description but what I thought were throttle percentages are gonna have to be good enough for now

Tom

[oab_au]

Originally Posted by Nomake Wan

2.) Duty Solenoid B remains at 5% when unlocked. When the torque converter locks, the solenoid jumps to 50% and then transitions from 50% to 95% gradually. If the transmission is in "Normal" mode when you disengage the cruise control, it drops to 55%, but does not go down to 5%. So when driving around without Power Mode, the torque converter appears to be in a semi-locked state. Odd. It'll go down to 5% if you start to brake for a stop, though. Presumably to prepare for sudden acceleration.

3.) Duty Solenoid C is at 65% about 95% of the time when driving around normally. So whatever 65% represents torque-split wise, that's what the USDM cars maintain. Power or Normal mode doesn't make a difference. Also, as before, the only time that Duty Solenoid C went to 95% was when the shifter was in P or N. The most I've ever seen it at while driving was 70%. And the lowest of course was 5% when launching from a stop.

4.) Duty Solenoid A remains at about 58% most of the time when just cruising, and alters based on a direct relation to throttle input.


Hope this helps some!

What you have observed with Solenoid B " the solenoid jumps to 50% and then transitions from 50% to 95% gradually" is the way it ramps up reduces the engagement shock. I've no idea why it hangs at 55%.

The Duty cycle sent to Solenoid C, varies with the inputs like. Gear position, throttle opening, road speed, and 'out of limits' wheel speed difference.
The condition giving the highest pressure applied to the clutch, would be, full throttle, no speed, 1st gear, or wheel spin.
The least pressure would be light throttle, high speed, 4th gear.

As I said before the PWM sent to the clutch is different for the two types of AWD, Transfer and VTD, they are opposite signals. So when You read the US Transfer signal, and Phil reads the VTD signal, they are opposite.

Harvey.

[b3lha]

Originally Posted by Nomake Wan

I know that math isn't always the order of the day, but I did some anyway, assuming that the TCU uses a linear plot for torque split. So here's the math...

We'll take the SolC duty cycle and call it 'x'. 'x' can go from 5 to 95. For simplicity's sake, we'll have 'y' represent the rear torque split, which can go from 50 to 0. So when x=5, y=50. And when x=95, y=0. Assuming this is a linear plot, that gives us the equation

y = (5/9)x - (25/9)

Now, if we then assume x=65, which is about what my car registers on SolC during normal driving, this gives us a result of y=33.3. So the torque split would be 67/33, approximately.

If you then think about how the JDM VTD box advertises a torque split of 35/65, it starts to sound rather interesting. Anyway, that's just some math. Whether it means anything or not is up to the hands-on mechanical guys.

Good thinking. I hope it is a linear relationship, but LAN said in another thread that it is not.

If it is a linear relationship I have a doubt about your maths. Or maybe mine. It's late (here) and one or both of us is wrong.

Your x coefficient "5/9" is positive therefore your graph will slope upwards.

But I think it should slope downwards, from (0,50) to (95,0). So the coefficient should be negative. By my reckoning the equation would be y=(-5/9)x + (475/9). Your x=65 would give y=17, therefore 83:17 torque split.

Or, if the known points are actually (0,50) and (100,0) [which makes more sense, 100% duty = FWD] it becomes easier y=(-1/2)x + 50. Then x=65 gives y=18, therefore 82:18 torque split.

[oab_au]

Originally Posted by Nomake Wan

I know that math isn't always the order of the day, but I did some anyway, assuming that the TCU uses a linear plot for torque split. So here's the math...

We'll take the SolC duty cycle and call it 'x'. 'x' can go from 5 to 95. For simplicity's sake, we'll have 'y' represent the rear torque split, which can go from 50 to 0. So when x=5, y=50. And when x=95, y=0. Assuming this is a linear plot, that gives us the equation

y = (5/9)x - (25/9)

Now, if we then assume x=65, which is about what my car registers on SolC during normal driving, this gives us a result of y=33.3. So the torque split would be 67/33, approximately.

If you then think about how the JDM VTD box advertises a torque split of 35/65, it starts to sound rather interesting. Anyway, that's just some math. Whether it means anything or not is up to the hands-on mechanical guys.

Wan, the % of Duty cycle sent to the clutch, and the actual torque split may not be in line. The % of PW is exact, the actual grip of the clutch is not. So we just have to use the % and assume that the clutch follows suit.

The 36/64 of the VTD is a mechanical variation, the PW signal can only move it from there to 50/50.

Harvey.

[b3lha]

Originally Posted by TomsSVX

ok Here is what we have...

At idle in Park or Neutral: 95%

Idle in D or R: 70%

Coasting in D: 70%

1/4 throttle accel: 55%

1/2 throttle accel: 35%

3/4 throttle accel: 33% but quickly begins to rise up to 35 and further up as you accelerate.

Full throttle accel: 5-15% and quicklu rises to 35% and further up as you accelerate.

Now as you do your match remember 0% is 50/50 and 100% is Front Wheel Drive only

Now, unfortunately it is a real select monitor so I cannot see more than one parameter at a time. I wish I could see this and plot it in relation to throttle position to get a more accurate description but what I thought were throttle percentages are gonna have to be good enough for now

Tom

Thanks a lot Tom. That's good information. I'll take a look at the ECU program tomorrow and see if I can find out how it decides what the duty cycle should be.

[oab_au]

Originally Posted by b3lha

Good thinking. I hope it is a linear relationship, but LAN said in another thread that it is not.

If it is a linear relationship I have a doubt about your maths. Or maybe mine. It's late (here) and one or both of us is wrong.

Your x coefficient "5/9" is positive therefore your graph will slope upwards.

But I think it should slope downwards, from (0,50) to (95,0). So the coefficient should be negative. By my reckoning the equation would be y=(-5/9)x + (475/9). Your x=65 would give y=17, therefore 83:17 torque split.

Or, if the known points are actually (0,50) and (100,0) [which makes more sense, 100% duty = FWD] it becomes easier y=(-1/2)x + 50. Then x=65 gives y=18, therefore 82:18 torque split.

Phil you can't have a Duty cycle of 0% or 100%, or it is not a Duty cycle it is DC. It is usually quoted as 5% to 95%.

Harvey.

[b3lha]

Originally Posted by oab_au

Phil you can't have a Duty cycle of 0% or 100%, or it is not a Duty cycle it is DC. It is usually quoted as 5% to 95%.

Harvey.

I know the TCU doesn't usually generate a duty cycle of 0% or 100%. The TCU actually checks this in it's calculation. If the result is less than 5%, the TCU sets it to 5%. If the result is more than 95%, the TCU sets it to 95%. However, I've seen some instances, error conditions for example, when the TCU will lock a particular solenoid to 0 or 100.

In theory, 0% will result in a 50:50 and 100% will result in 100:0, even if the TCU does not normally use those values.