Is this possible? (speed seonsor issues)

[bbechtel16]

I have been having problems with my "car's abilitiy to know how fast it is going". The speedometer would swing all around while driving (anywhere between 0 and the actual speed you are traveling), transmission shifting erractically in accordance with the speed it would display, and of course the odometer reading way under actual milage traveled. The vehicle reads and displays speed correctly when under heavy engine acceleration or decceleration load (3/4-WOT or downshifting into 2nd at a high rate of speed). I took it to the garage and they replaced the speed sensor assembly unit, (at $130 for the part :shock: ) however this did not solve the problem. They talked to a local GM dealer, who told them the instrument cluster needed replaced. They couldn't source one with their junkyard, so they released it back to me. I however, find it hard to believe that a bad cluster would also effect the transmission shift, so I questioned them, but they insisted, explaining that the speed sensor sends to the cluster and then everywhere else it needs to go, though I'm not sure they're confident. In conclusion, does anyone have any input into this issue?

[GnatGoSplat]

Could be the ECM.

Speed sensor sends info to the ECM. ECM sends info to the cluster, cruise, etc.

 

Speed sensor does NOT directly connect to the cluster.

[bbechtel16]

Would you guys suspect ECM or some connection between? Anyone have an ECM I could borrow?

[GnatGoSplat]

I normally suspect ECMs because the 88-93 ones have a fairly high failure rate.

I'd lend you one if you were local to me, but I bet you're not.

[White93z34]

i had this same issue last winter with my z34, replaced the VSS to the tune of $70 from the dealership and it didn't help one bit.

 

swaping PCMs didn't help at all

 

for me it ended up being wires that were slightly damaged from my wreck, so i ended up going over them all, and cutting and resoldering them back together, it took forever to get it all done right, but i haven't had that problem since then.

 

i notice you say that your cars got a R title, what hapiened to give it that designation?

[jeremy]

I had this exact problem when I bought my cutlass. One of the wires was "broken" as well. It certainly doesn't have anything to do with the cluster

[bbechtel16]

It was a very minor rear ending from what I understand. The original hood is still there, just slightly creased at the front, the bumper and grille were replaced I believe. I guess I'll try looking over those wires, *sigh* stupid car.

[bbechtel16]

Resolved: For Reference:

 

I never got up the ambition to check that out. I took it to Aamco. Only $135 later (plus the $200 for the orginal worthless work by the garage ) it turns out it was indeed the wiring harness. Seems to be working great now. I'll be taking a 200 mile round trip to Philly on Thursday; and I'll be changing out the oil for some nice Amsoil tomorrow. We'll see what kind of MPGs I get.

[jeremy]

Thanks for taking the time to come back and update the thread with the "fix". Hopefully it will help someone with the same problem in the future.