converter locking and unlocking

turboaddict2

New Member
Joined
Apr 11, 2002
Recently my TC isn't locking up when it should be. My car shifts to 4th and locks up at 50 mph. Today I was cruising at 70 mph with the converter unlocked because it was around 2000-2100 rpm. Could it be something wrong with the TCC solenoid? Or maybe the switch at the brake pedal isn't making contact? See sometimes it will actually lock up at the right mph(50) then all of a sudden unlock.
 
4th gear pressure switch praps. Rig up a manual switch at the adl connector and see if you can maually lock it on command. Top left and right on the plug under the radio
 
How should I hook up the switch? What parts do I need? Never did this before so I need some help on it. Thanks!:)
 
A bit of wire and a switch makes it easier but even a paperclip will work. All you need to do to force the TCC solenoid on is to connect the upper left and upper rightmost terminals in the ALDL connector under the dash by your right knee.
 
Ok I locked the converter with a paperclip and it does lock up. Then when I took the paper clip off it unlocked again. Does that mean the TCC solenoid needs to be replaced?
 
No, the solenoid (along with the converter & transmission pump) is working fine as evidenced by your test. It seems that the problem lies in control of the solenoid. It's not being properly commanded.

The paper clip test also discounts the brake switch as being a problem. That's because the +12V to the solenoid passes through the brake switch. The paper clip is merely providing a path to ground for the solenoid. Since you successfuly locked the converter by grounding it, the +12V side is fine.

The ECM activates the solenoid by grounding it as well. Something is affecting the ECM's ability to lock your converter consistently. At least you've narrowed down the problem.

Could be VSS signal, 3rd/4th gear pressure switch signals, TPS signal, coolant temp sensor reading, ECM, PROM. Do you have access to a scan tool? Something like an OTC Monitor 2000/4000 would be helpful as it provides a visual indicator as to when the ECM commands TCC apply.
 
Yeah I think its not being commanded correctly too. I'm thinking it might be the chip I got. Its a turbotweak chip from Eric. The problem never happened to other chips I tried. I emailed Eric and haven't heard back yet. How do I check the 4th gear pressure switch signal?
 
My TC was locking and unlocking sporatically too... In my case, it's probably a bad VSS, being that it was improperly reading the mph. It's now no longer reading at all, so the TC isn't locking at all (I have an AVC dash with an external VSS). This is shown by the fact that the scanmaster reads 0 mph while driving.
 
my NEW TC locks and unlocks right around 45-50 mph but then stays unlocked when i go past 50...it nevers stays locked under load and it never locks when i race either...i have a manual switch and the converter WILL stay locked when i flip the switch until i go into a heavy load...

i have a brand new tcc solenoid and brake switch...i have a feeling my converter is bad...it doesn't hold a lock when i put it under some load...my scanmaster says my speedo is right dead on...
 
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