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Thread: Error code P0743
03-26-2012, 12:37 PM #1
Error code P0743
Hi guys! I'm still having issues with my 99 Suburban. on the 4th of Jan, the tranny emptied itself on a freeway in the middle on the night on a freeway. since then I have replaced the tranny and the torque converter with a rebuilt one. My original trans was showing a code, P1870, trans component slipping but the new one came up with a P0743 Torque Converter Clutch Solenoid. I drove the truck 131 kms before it too cooked itself and spat fluid out on a hill.
The shop I bought the TC and the Tranny from says that it must have been my fault during the installation, but I really can't see it. The shop and I had words, VERY strong words, because he didn't send the tranny when he said he would, and now he is getting smart assed about the whole thing.
I really want to know what would cause this error code and is it something that I could have done? The trans is now at his shop, but he said he will look at it in his own time.
03-26-2012, 01:20 PM #2
The Torque Converter Clutch (TCC) solenoid valve is activated, with the gear in D4, by the Transmission Control Module (TCM) in response to signals sent from the vehicle speed and the Engine Control Module (ECM). Lock-up piston operation will then be controlled. When the torque converter clutch solenoid valve is activated, the torque converter lockup clutch will engage creating a 1 to 1 RPM ratio between the transmission input shaft and the rotational speed of the torque converter. Lock-up operation, however, is prohibited when A/T fluid temperature is too low. When the accelerator pedal is depressed (less than 2/8) in lock-up condition, the engine speed should not change abruptly. If there is a big jump in engine speed, there is no lock-up.
Causes......Possible causes of a Code P0743:
- Faulty torque converter clutch solenoid valve - Torque converter clutch solenoid valve harness or connectors - Torque converter clutch solenoid valve circuit is open or shorted - Low transmission fluid level - Dirty transmission fluid The Error code is generally activated on detection of the following conditions: By performing a voltage drop test, the ECM detects that the TCC solenoid circuit is open or shorted.
Last edited by 99'HEARTBEAT; 03-26-2012 at 09:03 PM.
03-29-2012, 11:23 PM #3
I can't test it now as the wiring and solenoids are molten. Do you know what would trigger this problem? The transmission guy says that it is from the cooling system, I think he doesn't want to honor his warranty. We had very strong words about the way he promises to deliver be Saturday but then doesn't send it until Friday and the delivery is for the following week. We butted heads over it and now he isn't in the mood to assist at all. I will rebuild the thing myself and do what ever needs to be done to get her running again. This has been 3 months without my truck. PLLEEEEEEAAAAAASEEEEEEE HELP! :D
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