bad_idea

1990 I6 AW4 231

The transmission shifts good. The torque converter isn't locking up at freeway speeds. I'm not sure if the TCU is sending the signal to lock the converter or if the solenoid is bad. I've replaced the TPS already. I've lifted up on the brake pedal at speed and it hasn't engaged the lock up.

I want to hook up a test bulb to C14 on the TCU harness. Something semi-permanent to monitor the output of the TCU to the lock up solenoid. My assumption is if the light turns on, the solenoid must be bad. Or worse, the converter lock up function is broke. Is there an issue with wiring a bulb from C14 to ground?

If the light doesn't turn on then it is one of the following: TPS (new), NSS (hope not to deal with that), or VSS (no idea on that one). Any other inputs that control the lock up function? Any tech on NSS or VSS?

nujeepguy

you could put a low wattage bulb or led almost anywhere,certanly if volts are fed with a relay. an led/resistor anywhere. very low current

then decide from there.

cruiser54

Did you check the switch for adjustment, and continuity when the pin is pushed in?

bad_idea

I have not. I'll check that. Does the FSM have a procedure for that?

cruiser54

To test it:

Unplug the connector. Using a meter set on ohms, touch a lead to both wires. Push switch plunger in and there should be continuity. Release the plunger, should be no continuity.

To adjust:

Push the pedal down a bit. Push the switch toward the pedal. Release the pedal. It's adjusted.

bad_idea

The switch was out of adjustment. Was barely touching the pedal, not pushed in at all. Think the adjustment was thrown out of whack when I swapped in the WJ booster and master.

There is continuity on the switch when it is closed (plunger pushed against pedal arm) and no continuity when the pedal is pushed down. Are you sure about the switch having no continuity when the plunger is pushed in? Seems odd mine is testing opposite of what you spec'd out.

I'll see if the converter locks up on the drive in tomorrow.

cruiser54

You sure about that?

bad_idea

Brake pedal arm pressed against switch button I had continuity. Press the brake pedal down, open the switch, and meter read OL.

cruiser54

Isn't that what my post says?

bad_idea

What do you get when you cross an elephant and a rhino?

Elephino.

I had trouble understanding what you were saying, not that you misspoke. I'm just dense sometimes. I assume then my switch is likely good. Hopefully the converter will lock up on my ride to work tomorrow.

What inputs does the TCU look for to operate the lock up function? I am finding conflicting answers on the inter webs. I am having trouble locating info on the lock up function in the tech manual. Thanks again.

cruiser54

LOL. You were right on!! I went back and changed my post!!! Sorry. Couldn't help myself.

bad_idea

Nice. This $&#^ Jeep has been confusing the hell out of me since I bought it, don't need any help from you! Most troubleshooting I have ever had to do with a vehicle. Your knowledge has been invaluable so far cruiser. Thanks again.

cruiser54

You tested it!! And questioned the results. Proud of ya.

bad_idea

And the converter locks up. Check another issue off the list. Next issue is the cooling system and then the oil leaks.

cruiser54

Simple inspection and adjustment.....