dodge no 4th gear electrical problem (I think)

[Turbo6justin]

okay this has been killing me for a long time I have a '95 Dodge 2500 HD cummins powered. everyone knows the auto tranny sucks ass but mine more than most since it will not grab 4th gear anymore. here is the whole story it might get a bit long but there is a lot to say please stick with me. it has not been driven for a while but the problem was there when it was last being driven.

for a while right before it was laid up the overdrive didn't want to engauge. you could flick the little dash switch and it would sometimes engauge sometimes not then at the very end it would try to for about 2-3 sec then slip back into 4th. now it never does shifts. the rest of the tranny shifts fine actually better than I would expect. I am leaning toward electrical since that switch is controled by fuse #11 red 10 amp, the only other things on that circuit are the overhead counsel and the buzzer. neither of these work either. the fuse is of course fine and there is power in and out of the fuse block, there is power up to the overhead counsel on 2 wires (ignition on and off) but no power to the OD switch.

so yesterday I was screwing around with it and figured why not just try to get it to shift. I have a torque converter switch coming off the ECM that works great so I figured I'd do the same thing with the OD switch, went to pin 55 in the ecm wired it through a switch to ground and tried it and got nothing. getting more frustrated I figured there are three wires into the tranny one is the TC switch one must be the OD solenoid other is unknown. I soldered in 3 sections of wire and took it for a drive, connected each one to ground to se it it would shift and nothing then hooked each one to 12v and still nothing.

I am starting to think the solenoid in the tranny itself might be bad but that doesn't explain everything on that circuit not working. there is a whole mess of wires behind the dash that I really don't want to dig into yet and I can not find wiring diagrams for this to save my life.

SO if anyone has wiring diagrams especially of the OD switch overhead counsel or the whole tranny wiring design please please please send them to me. I need to get this thing into 4th I need to use it next weekend and time is running short and driving 4-5 hours at 58mph at redline in 3rd is a PITA.

[jp junkie]

Did you check the TPS?

[hy_desert_4wheeler]

Your ABS light wouldn't happen to be on would it??I had a 93 with the same symptons and the ABS light on.. The ABS sensorin the rear axle was bad..

[Turbo6justin]

I did the very through cleaning of the TPS but did not have my trusty multimeter so I couldn't adjust the TPS. And I just noticed that the ABS light was kind of on and off which was a completely new thing. though the ABS light would go off.

I am still unsure cause the other 2 things on that circuit (buzzer and overhead counsel) went at or about the very same time.

any other ideas, I'll still drive it but I really hate runing it near redline for that long, though it really shouldn't hurt a diesel much.