• The site migration is complete! Hopefully everything transferred properly from the multiple decades old software we were using before. If you notice any issues please let me know, thanks! Also, I'm still working on things like chatbox, etc so hopefully those will be working in the next week or two.

4T65e TCC lockup hack successful to fix fishbite / TCC shudder & question

P

PCweber

New member
So I picked up a 2001 Bonneville with what felt like a misfire. Scanned it, no codes. Swapped out coil modules, plugs, wires, no change. So I thin noticed when it was cold it did not do it and then realized the TCC does not enable until warmed up. I then test drove and if I lightly pressed the brake to disengage TCC it would stop the fishbitting instant so I knew it was TCC related and only happened when TC locked. So I did some massive Google searching. Found people were cutting the brown with ont eh trans plug to disable the TCC permanent. Also found guys who would cut the wire but wire a switch into cabin to turn it off/ return to stock. I did this, worked great. I then read more deeply that the TCC lockup signal is a PWM modulation of supplying a ground to one side of the TCC solenoid. I decided to test a full ground for a short period so it did not burn the solenoid out. It would perfect. TCC would lock and no fishbite with full ground. So I then tested with a 2.7 ohm resister in series and it worked. With an 8 ohm the fishbite returned. So I am wondering is the TCC solenoid is wore and wont hold the TC locked at the rate of the ECU PWM signal.

So, I have a few questions.

1. Could the ECU PWM signal be modified to supply a more “complete” ground?
2. Is what I read that the PWM signal is to smooth in the TCC lock and never really supplies a full ground?
3. When I switch in the ground with the 2.7ohms is much smoother that pure ground. Pure ground was a harsh engage. Any tips/ ideas further I should try?
4. Would an ECU swap be worth trying to see if the PWM TCC engage would be more sure?
 


Yes. Solenoid internal resistance is for 12v up to 100% dc
I think if you hooked up an ammeter you might not see much more than 750 milliamps
 
it would probably be a good idea to have the PCM tune set for zero torque converter clutch slip that way the solenoid is only grounded when torque converter clutch is activated versus something where it is grounded anytime the key is on.
 


Yes if you forget to turn it off and come to a stop or try to take off and lock it it'll slip. We used to do this on 700R4's and didn't have problems with it, but we also put in an unlatch to disengage it when you touched the brake and you would have to hit the switch to lock it up again. I would not do this on a 04+ since the damn PCM sees all.

Jeff
 
So what is the easiest/ least costly way for a non tuner like myself to get or tune the PCM to TCC non slip? I have laptop, etc.
 
You must log in or register to reply here.
Back
Top