LS1LT1 Forum : LT1, LS1, Camaro, Firebird, Trans Am, Engine Tech Forums - View Single Post - 4l60e no lockup, no codes, trans is otherwise excellent
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post #2 of (permalink) Old 09-23-2017, 08:22 AM
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Join Date: Sep 2008
Location: Fruitland Park,Florida
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When you say no codes stored, did you reach that conclusion by not having the ses light on? Or did you scan for codes? If you didn't scan for codes, do so. This is because there are codes that don't light the ses. But cause non lockup of tcc.

There are many things that can cause non lockup . 1st, the vehicle must meet certain conditions for lock up to engage. A factory service manual will tell you what conditions must be met to engage lock up.

2nd the brake switch does affect lock up. Some cars have 2 brake switches, and some cars have the brake lights and tcc interrupt built into 1 switch. You will have to consult the service manual to know which you have.

The tcc interrupt switch is a normally closed switch. This means there is power transferred through switch until you push on the brake pedal Then it releases lock up. If the switch is stuck on,, tcc will not engage.This switch communicates with pcm. When swich is open, pcm cuts ground to tcc.

On f-bodys, switch has both brake lights & tcc interrupt.

Other problems you may have include, no power to tcc. Power comes into trans on pink wire. It goes to 3-2 solenoid. It then is internally connected to tcc solenoid. You need to do a key on check of tcc to see if it has battery voltage. What makes tcc engage is that pcm provides the tcc ground on the white wire going into trans.

So if tccsolenoid gets no power, even when pcm supplies ground, tcc won't engage.

You can test tcc engagement by splicing a wire into the white tcc wire going to trans. Run the spliced in wire into passenger compartment. Attach wire to a switch. Attach another wire to other side of switch and run to a good ground.

You can test drive your car. Every time you turn on switch, tcc should engage. If it doesn't either tcc bad, no power to tcc, or converter clutch is toast.

Last edited by cocobolo95; 09-23-2017 at 08:32 AM.
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