chbarnha

I have a question about my 93 3vze automatic transmission. I have noticed that when it is wet or there seems to be moisture, that my speedometer will jump back and forth and ocassionally stop working all together for a while. Some times it is fine other times it will do this sporadically. This morning and one time before this the speedometer stopped working and i came to a stop at a light. When accelerating away from the light the truck seemed to surge forward but will not shift into second or third gear. Any ideas as to what could be causing this and how to possibly fix it? Could it be related to the speedometer not working? And how could i fix the speeedometer from doing this if there is a way? Any help is appreciated... thanks ahead of time.

chbarnha

Forgot to mention that if i cut the truck off and restart it, it runs just like it should with no problems shifting.

chbarnha

anybody have any ideas?

scope103

Probably VSS1 speed sensor. 15-20 years is about their lifetime. About $190 at RockAuto. Unfortunately, it is difficult to test, so at least inspect the wiring.

chbarnha

would the vss1 speed sensor have anything to do with the transmission shifting like i explained? not sure kind of new to the 3vze. or would that more than likely just fix the speedometer

scope103

Do you have 4wd? VSS1 is aft of the transfer case, so it provides the MPH signal. The transmission, forward of the two-speed transfer case, has its own speed sensor (VSS2). Since the transmission throws separate codes for each sensor http://personal.utulsa.edu/~nathan-b...31diagnosi.pdf , my guess is that either one could cause a shifting problem.

(Psst! Hint! Hint! What was that he said about .... codes?)

chbarnha

i dont have any error codes coming through on my ecm right now. thats why i was wondering. If you would have to guess which one would you change first. it is 4x4

scope103

VSS2 has nothing to do with the speedometer, so VSS1 is probably the issue. But use your judgment; it's not a cheap part.

(Did you actually read the codes, or are you just relying on the fact that nothing is blinking at you?)

chbarnha

i went through codes for my check engine light, and found that i had a faulty tps. Replaced that and the check engine light went off. I was unaware of checking the way with the overdrive button that it explains on the link youprovided. will have to try that tomorrow.

Green93

I have the same truck that you do and just went through this. I got symptoms like yours and as the VSS degraded it got worse and worse. Once the VSS starts giving faulty readings the truck will become almost undriveable. Basically acting as though it's in neutral. Happened to mo on the way to work. You can just unplug the sensor if this happens to you so you're not stranded.

chbarnha

ok, yeah that is pretty much exactly what it does, if feels and sounds like it is in neutral. how hard is it to replace this part, and which sensor did you find it to be in your case. would unplugging the sensor have any negative effects on the transmission or the truck?

Green93

The VSS I had issues with is on the passenger side of the transfer case and just in front of the driveshaft. It's one plug and one bolt to change it. I was planning a 5speed swap so I ran it for awhile while unplugged. I'm sure there are adverse effects to doing this but I just needed to get by a little until I parked it. Your speedo won't work but I just used an app on my phone for that. Like I said, it was short term.

Mine failed very randomly. I just didn't want you to get stuck with a tow bill or something, that's why I suggested just unplugging it if you needed to.

chbarnha

ok, thanks i do appreciate all the help guys. it only does it when it is wet, but i guess that is probably one of the simplest things to fix on that i can think of. better than rebuilding a transmission or such.