AW4

I have an AW4 in a 97 XJ with a ODBII code of P0743.


1. I've searched the forums.
2. I know a P0743 = Torque Converter Clutch Solenoid / Trans Relay Circuits.
3. It clears itself every so often then comes back.
4. I've done a visual check of plugs and such (haven't tried cleaning connectors/plugs yet).
5. Currently there are no symptoms that I can tell.
6. Since the 3rd solenoid only engages and disengages the torque convertor switching in and out of all 4 gears work perfectly.
7. I just had the transmission flushed, filter changed and new gasket installed. No signs of metal shaving n such.

So my questions are:
1. Besides if the torque convertor is engaged coming to a stop and it filling like it is about to stall, how can one tell its engaging and disengaging ?
2. Could it be something other than a dirty connector/plug somewhere?
3. If in deed it is reading the solenoid about to go out or sticking is there a test I can do without poping the pan off? For example, using a VOM check for the resistance across the solenoid wires.
4. What would the exceptable resistance tolerances be?

Any other thoughts, comments or insight is greatly appreciated. Thanks!

Regards,
BMan
97 XJ with a 3.5 RE lift, some of this and that but not much of anything.

if is engaged while driving above 45 mph your engine speed will only increase directly proportunate to your mph and also if you tap the brake pedal while slightly accelerating above 45 mph you will feel and see on your tach it come out hope that makes sense

Valve body solenoid resistance 11-15 ohms

some good info in this thread....

http://www.naxja.org/forum/showthread.php?t=929724&highlight=valve+body

While it could be an issue with wire continuity or a faulty solenoid, a far more likely culprit is a faulty TPS. The transmission computer uses TPS input signal to manage shifting, and starts showing weird shifts or shifts at the wrong time (my experience) or lack of shifts when the TPS starts to fail. This must be 100 times more likely than internal tranny problems or faulty computer problems.

Thanks for the input Gents!

McQue said:

Valve body solenoid resistance 11-15 ohms

some good info in this thread....

http://www.naxja.org/forum/showthread.php?t=929724&highlight=valve+body

Click to expand...

Good info, thanks man! Going to look at the thread fully in a bit. Will measure the resistance this weekend. U ROCK MAN! :thumbup: That thread didn't come up in my searches. I'll refine them next time! Sorry for being a newbie here!

4xBob said:

While it could be an issue with wire continuity or a faulty solenoid, a far more likely culprit is a faulty TPS. The transmission computer uses TPS input signal to manage shifting, and starts showing weird shifts or shifts at the wrong time (my experience) or lack of shifts when the TPS starts to fail. This must be 100 times more likely than internal tranny problems or faulty computer problems.

Click to expand...

Would a faulty TPS cause a the code I'm getting though? The shifting seems fine as does the ignition and fuel injection which I believe it controls also. Might just be time to replace it anyways, cheep and who knows when it was done last!

kennzz05 said:

if is engaged while driving above 45 mph your engine speed will only increase directly proportunate to your mph and also if you tap the brake pedal while slightly accelerating above 45 mph you will feel and see on your tach it come out hope that makes sense

Click to expand...

Seems to engage and disengage fine.


/me goes to find out about being a member!

bmanga said:

I have an AW4 in a 97 XJ with a ODBII code of P0743.....

Click to expand...

Every get this cleared up BMan? I swapped a used AW4 into 01 XJ today and this is the code I'm getting. Original trans had a bad planetary, but was not throwing codes, so I guessing it's the transmission harness or solenoid.

Other than the code, the trans works beautiful.

Tom

It's a circuit error so probably bad wiring

As I understand it, the code gets triggered when the TCU does not see a reduction in the engine rpm when the t/c lockup solenoid is engaged. A bad TPS can indeed cause this if the TCU thinks you're applying some throttle when it locks up, but your not and hence the rpm doesn't drop. It may also be looking at the engine rpm and output rpm and deciding there is slippage (ie, t/c didn't lockup when commanded) if the output is spinning too slow compared to the input. That's how it detemines a shift solenoid fault, btw.

On my XJ, all was fine with no codes before the AW4 swap and it popped up within 2 or 3 seconds after starting the engine. Drove it hoping it would help, but the code comes right back every time I clear it.

Seems easy enough to swap the harness off the old AW4, but I've got to drop the pan. I'll ohm out the solenoids and replace them if needed with parts from the other AW4.

Problem solved. Dropped the pan and check the solenoids directly. Torque converter lock solenoid was completely dead. No reading at all when ohming it out. Other two checked out fine.

Replaced with the one out of the original transmission and the CIL is has not come on again.