3rd gear only

[NomadTW]

could i put the one pin in the solenoid pin on the connector and another to an exposed piece of metal on the body of the car then to check if the solenoid is grounded?

[UberRoo]

A bad ground seems unlikely, but it would explain your ohm reading. The problem with that is that I'm pretty sure, (but not completely,) that the solenoids are grounded directly to the transmission. I'd say the transmission is probably very well grounded to the engine, which pretty much has to be grounded in order for the starter motor to work. Lastly, if there was a bad ground, the TCU would have trouble codes for all the solenoids. ...but, though I think a bad ground is unlikely, that's usually what everybody thinks until it's finally fixed. (Bad grounds always seem unlikely.)

Also, just because the plugs are secure, doesn't mean they're getting good contact. Bad connections can exist anywhere. Suspect 'em all, and check 'em all. If you can't get a good reading at the TCU wiring harness, test again at the harness below the throttle bodies. After that, test between that plug and the one near the TCU. A bad wire could be anywhere.

Also, I should remind you that we're assuming this is an electrical problem based upon a trouble code. It might be mechanical. I hope not, but this is just a reminder.

[NomadTW]

do you have any pictures pointing out which plugs i need to check for the trans?

there are like 10 connectors under there

[Sonar]

An easy way to check if the wire you found IS the groundwire for the sol's is to:

1. set the multimeter to "R" or "ohm" or the "omega char." (I CAN'T get the "omega" character to work!!, it just comes out to an "Ù") and lowest possible range (<1000).

2. then to test the multimeter, put the measuringtips together and it should read 0 (zero) or near to 0.

3. Then connect one tip to the sol's positive side in the connector, and the other to the stripped part of the wire you found (on the AT side!).

4. Now, IF this is the "right" groundwire, the meter should read, estimated to your previus reading, around 13 ohm's.


/Sonny

[oab_au]

I had a look to see if you were using the Legacy, or SVX, TCU with this box.

This gear box is not remotely the same as the SVX 4eat. This looks like a very late box. It would be easier, to use the Legacy TCU, than try to hook it up to the SVX TCU.

Which TCU did you use?

Harvey.

[oab_au]

I don't know much about the later box, have not seen one, BUT.

If you have a look at the solenoids, you can tell its got a 2/4 brake clutch, instead of a band, there is a brake solenoid . There is also a 2/3 Timing solenoid. There is another LC that i am not sure about.

The other new sensor, is the Turbine speed sensor. This would show gear box input speed, why?. I think this may be used for controling the clutch/brake timing.

In the old box, the 2/3 shift was timed by the hydraulic spool valves. The band had to release, as the high clutch is applied, otherwise 2/3 flair occured. This is why when the band needs adjusting, the band releases, before the high clutch comes on, and it flairs.

This box, looks like it has both the brake and clutch applied by the TCU. Thats what i think the Turbine speed sensor is for. It shows the speed difference of the turbine and the engine. This will tell how much slip, therefor torque, the converter is under. This is better than using the throttle sensor to show load, for timing the shift action. Should be a better box.

You can see what I mean that the SVX TCU won't run that box. It needs its own TCU. I think it would be easier to mate the Legacy TCU to the SVX, ECU.

All the best
Harvey.

[NomadTW]

sorry about that... it was not until later that i realized that that legacy service manual i have is for the 2001 legacy... i will try to find one that is for the 91 legacy as this trans is from

[Sonar]

I have the -90-92 4EAT manual at home (and a spare gearbox also, to my -90 Legacy), I could scan some pages if you want to.

And if I remember correctly, this 4EAT is very similar to the SVX US-4EAT, but differs from EURO-SVX 4EAT some.


/Sonny

[NomadTW]

if you could scan the wiring diagrams for the transmission that would be great...

[oab_au]

Sorry to give you a bumsteer.

Yes, it might be better to check the right wiring diag. Though it is a wake up, for anyone going to use a late box

Back to square one.

Harvey.

[NomadTW]

i can't believe i didn't notice that

[NomadTW]

nobody mentioned that the car should be on when i tested the leads.. so it wasn't...


i just did it with the car in the on position (engine not running) got a reading of nearly no resistance between pin 13, and a reading of 26 for pin 14

so does this mean that the wiring for the solenoid on pin 13 is reversed?

it seems logical to me that this is what that reading would mean

no resistance from ground to pin 13 would imply that pin 13 is also ground and pin 13 should not be ground, pin 13 should be positive to the solenoid..

is my inference correct?

[Sonar]

Hi!

Now I'm home and looking in the service manual of the 4EAT.

Sorry to say that my scanner is no worky, but I got one at the office too, but that have to wait until Monday then.

From the Manual I cannot tell WHERE the connectors are located, but I'll think that the connector you are measuring on is the B33 connector, a 16 pin connector.

You should NOT have ANYTHING switched on when doing these measures!! (disconnecting the negative battery pole is the safest).

1. Pull apart the B33 connector, and grab the one at the AT side, now identify the numbers:

• 14 Shift sol. 1
• 13 shift sol. 2
• 15 shift sol. 3
• 8 Duty sol. A (Line pressure control)
• 5 Duty sol. B (Lock Up control)
• 3 Duty sol. C (4WD transfer control)
• 10 Power System Ground Line

2. All shift sol. (13-15) should read 20-30 ohm's to pin 10 (ground).
measure each one of them by putting one tip at the solenoids number at the connector and the other one to pin 10.

3. Duty sol A, pin 8 should read 1.5-4.5 ohms to pin 10
4. Duty sol B, pin 5 should read 9-15 ohms to pin 10
5. Duty sol C, pin 3 should read 9-15 ohms to pin 10

That should do it ...


/Sonny

[NomadTW]

well with the key to on i got a reading of 25 to pin 14 and 0 to pin 13(the broken one)

i get full closed with the key off from all pins

so the broken solenoid has no restance...

i called the trans shop that worked on it, but the guy that would have any answers is on vaca... grr

i hope you guys can help me out with this i really need this car to run

[NomadTW]

ugh...
90-92 legacy chiltons diagram...