TCC override.. how ?
Thread Starter
Navigator
Joined: Jul 2002
Posts: 9
Likes: 0
From: Llandrindod Wells Powys
TCC override.. how ?
I have read that it is possible to force the torque convertor cluth to engage by grounding pins on the ALDL connector ? Is this true? Is it connecting pin F to pin A ? If I do will it permanently screw things up ECM wise ? The TCC is working, but not consistently: it'll go for 30 miles crusing without engaging, then do another 20 or 30 working fine.
Thanks to Bluvette85 for your reply to my earlier post on TCC lock-up things: No nearby C4 ECM's in Wales,UK, I'm afraid !
Thanks to Bluvette85 for your reply to my earlier post on TCC lock-up things: No nearby C4 ECM's in Wales,UK, I'm afraid !
Team Owner
Joined: Dec 2000
Posts: 90,675
Likes: 304
From: SE NY
Cruise-In II Veteran
Re: TCC override.. how ? (brianswelshc4)
I have a SPST switch across pins A&F on the ALDL in my IROC to force TC lockup in any gear above 1st (the 700R/4 cannot lockup in 1st gear).
I also have a mini-LED in series with a 2.2kOhm resistor across those pins as an indicator. When lit the TC is not locked. This also lets me monitor the function by the ECM to see if the lockup command is being sent to the servo in the tranny.
I've used this forced lockup when drag racing but rarely on the street.
This mod has no effect on the ECM operation nor it's attempt to control TC lockup.
I also have a mini-LED in series with a 2.2kOhm resistor across those pins as an indicator. When lit the TC is not locked. This also lets me monitor the function by the ECM to see if the lockup command is being sent to the servo in the tranny.
I've used this forced lockup when drag racing but rarely on the street.
This mod has no effect on the ECM operation nor it's attempt to control TC lockup.
Thread Starter
Navigator
Joined: Jul 2002
Posts: 9
Likes: 0
From: Llandrindod Wells Powys
Re: TCC override.. how ? (65Z01)
Thanks! I've rigged up a switch today and it works ! I guess I will need professional advice on why the car is not always doing the TCC thing properly itself: As I say its connected with the fan being on all the time, I suspect, and so not going "closed loop", but I can't tell easily. ('86 C4 Auto)
Team Owner
Joined: Dec 2000
Posts: 90,675
Likes: 304
From: SE NY
Cruise-In II Veteran
Re: TCC override.. how ? (brianswelshc4)
Three things are required for the ECM to go closed loop:
1) coolant temp must reach prescribed level (about 150deg F)
2) O2 sensor must reach operating temp and function properly
3) certain amount of time must have elapsed since startup
And of course the ECM will come out of closed loop at WOT.
If the main fan is being turned on all the time by the ECM either the coolant temp has reached prescribed temp or the A/C line pressure has risen too high.
I believe there are two coolant temp senders, one in the front of the block and one elsewhere. One sends data to the dash readout and the other is used to control the fans, etc.
To test for closed loop operation jumper ALDL pins A&B, start the engine and watch the flashes of the SES. After a few minutes of so the flashes will slow to about 1Hz when the ECM goes closed loop. The on/off periods will be of equal duration if the air/fuel is stoch.
I've never driven the vehicle in this diagnostic mode but, if both temp sensors are ok, you could try it to see it the ECM is going open loop when the TCC unlocks.
1) coolant temp must reach prescribed level (about 150deg F)
2) O2 sensor must reach operating temp and function properly
3) certain amount of time must have elapsed since startup
And of course the ECM will come out of closed loop at WOT.
If the main fan is being turned on all the time by the ECM either the coolant temp has reached prescribed temp or the A/C line pressure has risen too high.
I believe there are two coolant temp senders, one in the front of the block and one elsewhere. One sends data to the dash readout and the other is used to control the fans, etc.
To test for closed loop operation jumper ALDL pins A&B, start the engine and watch the flashes of the SES. After a few minutes of so the flashes will slow to about 1Hz when the ECM goes closed loop. The on/off periods will be of equal duration if the air/fuel is stoch.
I've never driven the vehicle in this diagnostic mode but, if both temp sensors are ok, you could try it to see it the ECM is going open loop when the TCC unlocks.
Drifting
Joined: Nov 2001
Posts: 1,783
Likes: 2
From: Latham NY
Re: TCC override.. how ? (brianswelshc4)
I noticed my TC was locking up at very low speeds 10-15MPH. It wouldn't disengage when decellerating. Put in a new TC soleniod last night and all is well. The check ball in the original solenoid was stuck. I used a universal one that splices into the original wiring.
