AW4 Sensors

Getting ready for yearly off road adventure, need help getting Trany fixed. 1990 Cheroke, I6 MPI Aw4 Automaitic. Have replaced Tranny Filter and fluid, as well as engine tune up. Problem did exist before work was done. Started out the transmision would seam to float between shifts, then progressivly got worse, and now unless there is load on trans it acts like it floating in neutral. It seems to happen in all gears. Transmission fluid clean, and no sign of being burnt. ...First thing is to try and determine if its electrical or mechanical inside trans. In and effort to find out, I used on the trick off your site that basicaly shuts off TCM, which locks trans in current gear, that works, and what ever gear I turn the power to TCM off in, it stays in. So my question is it safe to assume its a computer or sensor problem? The second, does anyone know which sensors feed the TCM, their location, and a way to test them, as well as test method for selenoids inside tranny. I have adjusted the kick down sensor (Black button on cable attached to Throttle cable, and it it does change the point the symptoms show up, but only slightly. I tested the CPS on top of bell housing, and it reads within spec, and does pulse when cranking over motor. I have tried to extract trouble codes; however, I cant determine wich OBD system I have. It does have the two diag connection on passenger side under hood (2 connectors with yellow plugs) and have tried using the on/off /on/off key method, as well as shorting out two pins on large diag connector mentioned above. Still no activity at all from Check engine light. (have never seen Check engine light light up at all, even when key is first turned on) Yes I replaced bulb just be sure). engine runs like a top besides that. Any ideas/help would be greatly appreciated.

Bob

Your jeep uses a RENIX computer for engine controls and does not have the capibility of self diagnostics .It not use a check engine light nor does it use diagnostic codes.

I'd be looking at repacing the TPS on the throttlebody. The engine ECM and trans TCM share this sensor for throttle position feedback.
Another area to look at is the neutral safety/gear selection switch. It is located on the passenger side of the transmission. It not only acts as a neutral safety switch but also tells the TCM what gear you have selected. These are known to become faulty and are easily fixed by taking it apart and cleaning it.

thanks, Im getting somewhere...... I think... trying to test tps, I get 3.8 volts, but when I turn tps to adjust, I get no change? which pins do I need to read accross to test tps functionality>

Check the voltage with a digital meter, four plug connector. I run the wire over the rubber intake for the TB and make a very little cut into the wire. The book recommends sticking the probes into the back of the connector. The test is done with the plug connected, ignition on.
Between pin A and D is imput voltage and between B and D is output voltage. There are various values recommended for the output voltage, I prefer about 86% of imput voltage. Book recommends 82-83%. I usually end up with areound 4.7 volts in and close to 4.0 volts out.
I did have some resistance in the connector that was giving me fits, about a volt of resistance on my imput voltage a good connector cleaning cured this.
You may want to have a look at your speed sensor, I left mine unplugged once and my tranny had very little compression braking and/or sporadic downshifts.
Might also want to test the output voltage, while moving the throttle to the stop. I had one TPS, that had a hitch (dead spot) in it, which I finally found with an old analoge volt meter.

Well thenak you all for your help, I removed TPS, cleaned and soaked with wd40.. reinstalled and adjusted per spec.. Transmission problem eliminated. On to Electrical issue.. think its just a ground.. Thank you everyone for your assistance, the information here is what made it possible for me to fix my problem. I had been told by 3 people (non jeeper's) that I had a fluid presure problem and needed to rebuild the tranny. I have become intimately familiar with AW4 and RENIX system in the process, any assitance I can offer I would be more thanhappy to help anyway I can. thanks again..

Bob

PS This thread can be closed.