I have seen quite a few people writing on hear with the same problem. I have a 92 3/4 Ton dodge diesel 4wd truck, my speedo stopped and my overdrive won't work. I have followed the problem down to the fact that the vss was not spinning . It looks like the part that comes out of the transfer case(pinion drive gear?) should spin the gear ratio reducer(GRR), the slotted part that connects from the GRR to the PDG was locked solid and it looks like it rounded it out the piece that spins the GRR. My dealership said they do not make PDGs anymore. Where to I get one? And has anyone else had this same problem?

 

Try a junk yard they should be the same on gas trucks also.

 

Ya I live in a fairly unpopulated area. Hard to find good pars. Anyone know any good used parts resources online? Looking for part number 4329816 pinion drive gear. Any info would be appreciated. Thanks.

 

I cut an Allen Key of the size and milled one end square, ... it's still in there

 

Any good tranny shop Should be able to get you one. If you have the old one out, they can match the ratio much easier.

 

Might as well piggy back off of this thread. Lately, if my truck sits for more than a few days the speedo won't work. Will start working a few miles down the road. I haven't opened up the book, is the speedo drive connected directly to the tranny? (5 speed getrag here). Just need to lube her? uh huh huh

James

 

I replaced three VSS sensors on my old 92w250 with an A518 and they never fixed the problem for more than a few days....the overdrive won't work if the speedo doesn't go up high enough, my speedo went out when I was drivin 75-80 mph on the interstate and it dropped out of o/d in a hurry...not good! It ended up being a lot of crappy wiring that took some time to fix, but the vss wasn't my problem in the end....best of luck.

 

could you recommend any specific problem areas to check in the harness for issues? i am having the same speedo/O.D./cruise issue, and have given the harness a quick once over, but didnt find anything obvious.

 

The PCM is in I believe 92 and up trucks, (I think most of the intercooled trucks have them) which also regulates when the truck shifts into overdrive and the speedometer is run off it too. I cleaned up some of the wiring that looked horrible in the harness (it almost all looks bad on my rig) and it worked for a bit. Ran a new ground from the pcm to the battery, and that helped a little...3 vss sensors (2 of them tested bad from napa, which you may want to check), (that could be your problem too, I dunno) but still no long term fix so when my mechanic put a few brand new wires in from the PCM into the motor, checked some ground wires, cleaned some of the old connections up, it worked for about a month or so. The needle started fluttering again after that, and he did some more fixin on it and it seemed to solve the problem.....(probably 16 hours of time invested to get it right, luckily he didn't charge me much) if your truck is anything like mine, you got wires for things you don't even know from previous owners splicing things together.....when I get some money saved up I plan on re-wiring the whole thing (my 93) my 92 had so many wiring issues it gave me a headache, so I started over with a 93....some of these wires just seem to have ghost problems and I am no electrician, after fixing and fixing and a few days later, it just kept actin up, I took it to my diesel guy. Anyways, I hope that might give you an idea, hopefully you can figure it out. Once you do, I'd also get a potentiometer for your o/d shift...super cheap and well worth it.....

 

thanks, and, yea, im thinking of starting over with the wiring. and, ditching the PCM amongst other things all together! thats the beauty of these rigs to me is the SIMPLE riggedness. well there is nothing simple about electrical issues!

 

Yeah wiring sucks, but overall the first gen is so amazing....best of luck.

 

I had a similar problem on my 92 W250 diesel. Except mine turned out to be my crank sensor and after they fixed that they found my ECM (engine control module) was partially burnt out. They couldn't figure out which one went first, the crank sensor or the ECM. I had to go to the dealer for the ECM so I had them fix both while they were there. It was weird, it knocked out my overdrive first, then my blinkers, then my speedo. Ha! They couldn't even locate the problem at first, not until I got on DTR and got some responses from some of the guys on here. Called them and explained to them what I found out and they called me back about an hour and a half later and said "yep, you were right". Cost me $800, I got lucky one of the techs was able to find my ECM for $200. Works perfect now.

 

Thanks ppiggppenn, I rigged it with an allen key. Works for now and saved me some money. Had to rig it on my pinion drive gear side as well as both the gear ratio reducer and the piece that connects and spins on the pinion drive gear were stripped. Anyone with part 4329816 pinion drive gear drop me a line.