Short Term/Long Term Fuel Trim in Freeze Frame Data

1998 Cherokee XJ 2wd Limited
4.0
AW4
Chrysler 8.25 3:55 ratio
164k

So I've had a P0743 code for awhile indicating my TCC solenoid is having issues. When I come off the freeway after driving for an extended period of time I get a MIL when the TCC disengages and goes back to a fluid coupling. The TCC does operate correctly at 41 mph.

So here's the interesting part.......

I connected a DRB III to the DLC and pulled a Jeep code for the TCC......darn if I didn't write it down but I believe it was something like P1735....The code indicates a short to voltage at the TCC.

So, when the PCM commands off the TCC through the TCM there is still voltage present at the solenoid correct? I removed the TCM connector and found 10.4 ohms at the TCC solenoid. Spec is 11-15 so 10.4 is close enough as far as I'm concerned.

So Im thinking I have a chaffed wire on the 1-2 or 2-3 solenoid. Any thoughts?

Also, while looking at freeze frame data I saw my short term fuel trim was 3.1 and my long term trim was 3.9. I'd really like to see long term closer to 0 but was wondering what you guys were running.

Thanks!

No comment on the TCC, but +/-5% on LTFT is fine. It's when you see +/-double digits that you should start worrying about clogged injectors, clogged fuel filters, slow O2 sensors, and cracked headers/exhaust leaks before the upstream sensor(s).

Thanks for the reply. 5% seems like a lot to me for long term but hey, I won't worry about it. I have seen a bit of a dip in mpg over the last year or so. Upstream O2 is 1 year old (NGK NTK unit), tune-up hardware has less than 10k. I do a lot of in town driving and I'm pretty liberal with the skinny pedal. I could see the exhaust manifold. When I cold start it I hear a bit of an exhaust leak, but it quiets down after about 30 seconds (might be a little piston slap too) It hasn't gotten any worse in the 5 years I've owned the XJ. I get about 14-15 doing all short in town trips.

Still hoping someone out there might have some insight on the TCC problem. I have no problem dropping the pan and even replacing the solenoid harness but I'd like to be a bit more confident about it.

Did a bit more testing today after adjusting my NSS. I removed the connector at the TCM and then removed the connector underhood for the vehicle side of the solenoid harness. I checked for continuity between the TCC solenoid and the 1-2 and 2-3 solenoid. Everything was OL which tells me at least the harness is alright. I did Ohm check the solenoid again at the vehicle side harness with the trans warm and got 18 Ohms. Isn't spec 11-15?

So I could still have a wiring issue inside the transmission but I believe I'm dealing with a thermal failure of the TCC solenoid.

Does this sound reasonable?

I ended up replacing the tcc solenoid. All $190+ of it.:flamemad: Rock auto had the best price. The best part was I ended up getting a reboxed Aisin solenoid!:roll:

Just be careful, the first solenoid they sent was numbered correctly but mis-boxed. (I ended up getting a shift solenoid.)

Compare to the photo on the website. If this is your D/D, it will save you some down time. The tabs for the bolt are close, but different enough to not be interchangeable.

I ended up having to drop the pan twice. At least returning the part was relatively painless.