I've got a 96 XJ that's not locking the torque converter

It shifts great into 1-2-3-4 no problem but never attempts to lock the TC

I assume it's not the brake switch because my cruise control turns off when I press the brake and I've adjusted it but that didn't fix my TC problem

any ideas?

 

You'll need a meter to test the resistance of the lockup solenoid. The brake switch has 3 different sets of contacts. The input to the trans computer is on the same contact as the shift interlock and pcm, so if you need to press the brake to shift out of park, that part should be working

 

Do I need to pull the pan to check the resistance or is there a better way?

also yes I have to press the brake to get it into gear

 

I have just repaired this fault in my '96, and its great to have it back !

The best way to test is at the plug beside the dipstick.

You will need to reference the FSM to identify the correct color wire.

measure between that wire to battery negative terminal, and resistance should about 14 Ohms

Mine was open circuit

The problem turned out to be an internal break on the trans TCC harness wire, right where it bends and goes through a rubber grommet at the top of the trans (I pierced it with pins to check)

No new Trans Harness available, and changing out an older one is a challenging job

If it turns out you have any significant variation from 14 ohms, you will need to drop the pan, and remove and check the solenoid for proper operation

It is actually hard to tell, as it works opposite to the others, is different, and does not make a distinctive click like the others (suck/blow when open/closed is how I had to be 100% sure..and it did measure within spec

After a lot of thought, I decided to run thin 5A wire, just right on the gasket

This fixed the problem immediately, and it does not leak. I put a 10A fuse inline just in case the wire ever rubs through on the trans case, but I see no reason why that should happen

 

Here is the connector under the hood for checking the solenoids.

 

Here's the pinout of the trans computer connector, located under the passenger dash below the glove box. You can check that the stop lamp sense is working from there.