Hi guys, I'm new here been floating around for a while but now I need a hand and I'm hoping you RAM lovers could help a fellow Dodge lover out.
So I have a 1995 Dodge RAM. A couple of weeks ago I was going down the freeway with my truck and it was running perfectly fine other then the common speedo jumping around. Not more then +/- 5 mph. Eventually the speedo stopped working along with mileage gage and check engine light popped on. Then the typical not shifting past 2nd gear happened. So obviously I thought OK well most likely speedo sensor on the tranny or the one that's back by the rear axel near the pumpkin. Well I made it home but not without it stalling out while slowing for traffic. So I thought these are symptoms I have heard happen when speedo sensors go out. Iafter retiring the truck for the night I went out in the morning to drive to my local shop and it would not start over. It would turn over just not start. I did the good old turn they key trick to pull a code. I got cam shaft sensor. Which explains the not starting. So I had it towed to my shop. My mechanic told me after a few days of trying to diagnose my truck that the computer went bad and caused my alternator to go bad. So I had the ECU replaced along with the alternator. When I got my truck back it ran great. Speedo worked fine mileage gage was worki g fine. But 1 day after I got it I noticed a little jump on my .speedo. Uh oh I thought. This is not good. Now it's getting worse the more I drive. So I'm thinking OK maybe I need new sensors on the tranny or back by the rear wheels? Or could my ECU be going bad again? But if my comp was going bad wouldn't there be more syptoms then a jumpy speedo? There's no check engine light on now but neither was there right before my truck started stalling out like previously before. So I'm hoping maybe just maybe(fingers crossed) that my ECU is OK and maybe I just need to replace those sensors. Any thoughts? I just paid almost 700 bucks for alternator and ECU replacement only to have the same symptoms as when my speedo stopped working and my truck stopped shifting passed second along with the stalling out. What do you guys think? Please feel free to speak and sorry about the long post. But thanks in advance

 

Speedo is driven from the VSS on the output shaft of the trans. (or t-case, depending on if you are 2, or 4 wheel drive.) The sensor on the rear diff is just for the ABS.

Trans doesn't care about the PCM. All shifts 1-3 are purely mechanically controlled. O/D, and TCC are indeed computer controlled though. If you are having shifting issues in the first three gears, that is a separate problem.....

I would be tempted to pull the VSS, and have a look. It is gear driven off the output shaft, and just has a signal generator attached. If the gears are worn, you can get some strange behavior, same for poor connections. Keep in mind, the VSS is indexed in the housing, depending on what color gear you have, so, make a note of that before removal. Pull it out, see how things look, clean the connectors, and see if that improves anything. If it doesn't, replace the VSS.

Welcome to DF!