FYI: Note in the diagram in post #4 how the TPS interfaces with the TCM.

If the trans is downshifting when under load, the overdrive must be kicking out and the TPS is doing its part in lettng the TCM know where the throttle is.

 

Yep totally understand, thanks.

I've just driven it home and it was fine. Didn't miss a beat. I'm stumped.

I'm almost tempted to leave it as one of those 'Jeep moments' but I hate not understanding things and likely causes. If it wants something, I want to get it sorted.

 

And now I scan for codes look what I find:



Exactly the same code as before I had the solenoids changed. Oh dear.

 

Were the initial code(s) you had, cleared/erased?

 

Of course, sir. Codes were cleared.

 

The plot thickens...

P0171 is a lean air/fuel mxture has been indicated by an abnormally rich correction factor. Can you read live data on your device. If so, take a look at the Short Term Fuel Trim and see if it shows a hgh positive fuel correction, which can be caused by a faulty upstream O2S, vacuum leaks from the intake gasket/hoses, clogged or dirty fuel injectors, low fuel pressure, or a clogged Cat.

Comments?

P0700 just tells you a DTC has been set in the TCM.

P0756 might be a faulty shift solenoid B (2-3) was installed or there is a fault in its control wire from the solenoid to the tcm. You can check the solenoid circuit resistance from the TCM connector without dropping the trans oil pan if you want. Let me know.

 

Thanks CCKen,

I have had the 'running lean' code since I bought the Jeep, I have never been able to get rid of it, even after changing both o2 sensors and having them re-wired. I now believe this is because my Jeep runs on LPG. When I run the Jeep on petrol, I don't get this code.

P0700 - yep, aware of this one, although I wish I had a tool capable of jumping deeper into the cause of this code, however the P0756 is probably deep enough. I believe this is code that gets thrown the TCM simply puts its hands up says 'I've detected a fault' to the PCM.

P0756 - This was the code that made me change the solenoids in the first place. That, and the obvious trans issues that accompanied it. Since the solenoids have been replaced, the trans drives like new, so this code scares me somewhat. It now means the solenoids may have been changed for no reason, and the true underlying cause could be with the wiring as you suggest. This is looking more likely.

I think I have seen a previous post of yours detailing how to check the solenoid resistance so I will follow that and see what I get. I have to say though, I'm not confident with car electrics, something I would generally steer clear of. I also think I would struggle with this because this fault must be intermittent. Sometimes drives like new, sometimes feels like something is seriously wrong. Anyhow, I'll give it a go.

Thanks again for the help.

 

Intermittant problems can drive one to drink (been there, done that LOL).

A place you should check is the connectors next to the trans dipstck tube (see pic) wires going into these connectors have been found chafed and caused intermittant problems. Examine the wires to these connects closely and verify the connectors are clean and secure. You can see that the "TCA" connector carries the solenoids wires.

 

Ok I have just pulled the trans connector. It took a few minutes to separate them, they were stuck together quite well. The connectors seemed fine, nice looking metal tabs, unlike the corrosion I found on my fuel injector tabs a few months ago. All wiring looks good in the surrounding area, although I was limited to how much of it I could see as it's encased in tubing.

I guess the next thing to check would be the tcm. Hope that's not duff too... I hear the '97's need a replacement from another '97 and there are none for sale around here.