Hello this is my first post but I have been here a while reading the wealth of info on here. Great site people!!
Heres my problem 1992 Z28 5.7, I took it out today for the first time all winter and the speedometer stopped working. I did a search on here and think it may be the vss. My problem is when I pulled the codes it came back with nothing just 12's. No check engine light either. Anyone have any Ideas??
Thanks in advance JKaz

 

When my VSS was bad it would not throw any codes either. Get the numers off your VSS and get it from GM since there will be like 3 different ones for your car but the part stores sell 1 for all the cars so i dont know how well it work.

 

Uh, first thing to do is check to see if the ECM is getting a correct speed signal. If it is, then replacing the VSS isn't going to do a thing more than likely.

Sounds likely VSS isn't bad if you don't get a code, as the ECM is *probably* still seeing that signal.

Need to get a scanner on it to check.

 

if you're close to this location try this,

http://members.***.net/speedometerma...s.htm:burnout:

 

My car does the same thing after sitting for awhile. It's not the VSS as the ECM does not throw a code 24. My odometer works completely fine also when the speedometer does not. So the ECM is getting a signal. Also if the ECM was not getting a VSS signal, it would affect overall performance negatively. Then the problem must be mechanical in nature.

This is an intermittent problem in my case. I talked to Deadbird and he mentioned that sometimes due to lack of lubrication the speedometer needle becomes lazy. Try tapping on the guage cluster plastic after you have driven a couple of miles. Usually it perks the needle up.

When I take my dash apart next time to replace my headlight switch, I am going to lube the speedo needle with a few drops of light machine oil.

 

Hi Guys, Finally able to get a scanner on it. The ecm is getting a signal, also the crusie control works fine. the speedo and odometer do not work. This is a 92 so there is no speedo cable its fully electronic. Anyone have any Ideas or know of a place in NJ area I can take it to. Thanks in advance. JKaz

 

We deal with specmo: http://www.specmo.com/

I do not know if they sell to the general public, or only to GM dealers. You might want to call your local dealer (parts dept) and ask if they have someone local that they send their clusters to.

 

anyone?? ttt

 

I think you'll probably need to do some more searching. I'm sure electronic speedometer operation has been covered in depth.

All I know is the DRAC setup: VSS comes from tranny, DRAC converts that input to various output (2000PPM, 4000PPm, etc) and the various outputs go to ECM, Speedo, cruise, etc.

In THAT setup, if my speedometer didn't work, but the ECM was seeing speed, I would look at the speedometer, signal wire from the DRAC, and the DRAC output itself. At this point I have NO idea how you would go about looking at the signal to see where the problem is.

Having never had an electronic speedometer before, when I hit the key, the speedometer goes to "0" from wherever it was. If yours does that, then I would not suspect power or ground to the gauge itself, but that of course doesn't eliminate the gauge itself.

Your car might use a "4 out buffer" but that is a poorly educated guess.

 

I'm a constant reader and have been lucky to find this site, I've gotten so much great info about my "92 RS rag top. I'm not a great mechanic but any means, but I have had many problems with my gauges since I bought my "92. I spoke to a friend of mine who is a gifted electrical engineer about my gauge problems, speedometer jumping around or not working at all, gas guage problems, oil pressue gauge not showing true presure, he did some reaseach for me, and determined that the flimsy circuit board used by GM starting in 1991, is most likely the problems, just with age, the bumps and shaking of the car when driving may cause microscopic cracks in the circuit board that are not visible to the naked eye, causing gauge problems, there will still be contact made but not 100%, and according to him that would cause problems in getting accurate gauge readings. My '92 has 102,000 miles on it, I recently bought a gauge cluster taken out of a '92 RS, 305TBI, just like my car, it has only 40,000 miles on it, since I installed it, my gauge problems have vanished. I called my local dealer and the circuit boards are no longer available.
Another suggestion my friend gave me is removing the gauge luster and using an srpay on electrical contact cleaner to remove the natural build up of grime on the contacts. I hope my 2 cents worth of info was help to someone.

 

VERY INTERESTING.... I just put a new headlight switch in my '89 GTA, and while in there I cleaned the clear cover and the gauges themselves... now my speedometer is LAZY!!! At 10 it reads 5, at 30 it reads maybe 10... at 60 it reads about 30....

Hooked up my laptop w/ Datamaster on it, and VSS is good, ECM is seeing the correct speed.

So... whats the 'trick' to lubing this baby up ? Graphite ? Oil ?

This has to be whats going on with mine.

Gerry-
Norfolk, VA

 

In my case, a lazy speedometer just sits there not functioning. Your problem sounds a little different, but it may be the same.

I still have not replaced my headlight switch, so I have not lubricated the speedo needle yet. I plan to use a 3-in-1 machine type oil.

 

Well it works now!

Seems the needle MUST have moved when I had it apart, and I didn't get it back together correctly.

Moving it GENTLY counter-clockwise it goes past the 140 mark and you can feel a very soft non-audible click. If you then let go the needle hovers about 140. Going back clockwise through 140 you feel the same little click about 140.

After playing with this several times, several ways ( while driving down the road!! )... I finally got it to respond correctly.

So which way is WRONG, which is RIGHT ? Why did mine go whacky ? Thats a question for another day because I'm NOT messin' with it again!!!

Now... the clear plastic already had a CRACK in it... and I was not quite CAREFUL enough this time...

So guess what the next question is ??

Anyone have a part number for the clear cover ?



Gerry-

 

The F-body CD does not list the part number but Deadbird's site does.

The lens for the cluster is 25084190. According to www.newGMparts.com, it's still available and cost about $40.

 

Yep, I couldn't find it on the CD either.

Thanks for the P/N. I'll order it from Dal Slabaugh via email.

Got a link to Deadbird's site ?

Thanks again!!

Gerry-
Norfolk, VA

 

It's www.deadbird.org. Look at the Collision Guides.

 

Collision Guides. WOW! This is great stuff! Thanks for the link.

Gerry-

 

You're welcome. I'm always glad to help a newer, fellow enthusiast.