fantic238

I'm sorry, i completely forgot about you.
Anyway according to the 1993 diagrams the two systems have a common input that is the park-neutral switch on the tranny. The CC should disable when you shift to neutral or when in park, this means that if the NSS (neutral safety switch) is malfunctioning the CC might think you are in neutral and don't work.

SteveW

Sounds plausible. I'll crawl under it tomorrow and give it a once over.

I think I may just pull it, take it apart, and give it a quick rebuild.

It seems these are prone to failure at some point. It's about a 20 minute job to get it off, take it apart, clean it, and re-lube it.

I'll let ya know what I find.

Thanks for sticking with me on this.

SteveW

Well, after a long long long time, I'm still fooling around with this thing.

I know it's been a while, and this thread is dated, but I have still yet to figure out the issue, and am hoping for some fresh ideas on it.

to recap...

My 1993 GC Limited... one of the few GC's with an AW4.

The torque converter is not locking up... therefore my gas mileage is suffering BAD... When I say bad, I mean REAL BAD... I'm talking like I used to average about 15 MPG, now I'm closer to maybe 8 if I am lucky.

Now, something I noticed along with this, is when the torque converter does not lock, the cruise control will not work either. If the torque converter happens to lock while I'm cruising at highway speed, the cruise control will work.

Things I have tried:

I checked for vacuum leaks. I checked all of the tubing, and hoses, I even pulled the battery out and checked the vacuum reservoir. Also my HVAC controls work just fine, so the vacuum system is good.

I replaced the TPS and checked the voltages and it is good.

I changed the transmission fluid. The old fluid was not burn or very discolored, nor did it contain an abundance of debris or anything out of the ordinary.

I pulled off the neutral safety switch, disassembled it, degreased it, cleaned it inside and out, polished the contacts, and re-lubricated it with dielectric grease. Then I re-installed it, adjusted it and checked all positions with my VOM, and it was good.

Also, I checked and adjusted the brake light switch. It works just like it is supposed to.

Lastly, I figured I would try one more thing today.

I traced out the wires to the TCM, obtained 12v+ power, and put in a toggle switch. I cut the TCM output wire that goes the solenoid #3, wired it to the toggle switch so I can send power right to it.

I just got back from a quick test drive, and I can throw the switch and manually lock and unlock the converter any time I want.

So... where does this leave me? I have narrowed down the usual list of suspects for this issue, but now what?

Now at least I know the fluid is good, the neutral safety switch is good, the TPS is good, the brake light switch is good, and the solenoid is good. What else is there that would not allow the torque converter to lock, and would also not allow the cruise control to work? There can't be that many more things that both of these systems use in order to activate.

Any thoughts or suggestions would be appreciated.

fantic238

There is a speed sensor on the tail extention, did you check that one? Otherwise since the lock up works with the toggle switch (meaning it is not a hydraulic problem) the only thing left is TCM.

fantic238

Another thing might be the 32s, you didn't regear right? If you have a set of stock tires try them.

SteveW

That is the only thing I have not checked.

Do you know where I can find a diagram for it, or what wires should read what voltages or resistances?

I tried a set of stock tires, and no luck there.

Also, for the heck of it, last time I had it out, cruising at about 60 MPH, I locked the convertor and then tried the cruise control, but it is not working when I manually lock the converter. The only time it would work was when the converter would lock on it's own.

When you get a chance, let me know what I need to do to check that tail shaft speed sensor and I'll have a go at it.

Thanks again for your help!