Hi all,

My speedometer hasn't worked for some time after working on and off for a while. I found and replaced the VSS in hopes that was the problem. It wasn't as my speedometer still doesn't work.

Anyone have any suggestions as to what to check next?

 

Oh yeah, it's a 1991 RS 305 V8 Automatic.

 

I have the same problem and the same car that you do. I have tried to figure out the problem too and have posted about it but no one has a clear cut answer (most people say it is either the VSS or wiring but I think that it is neither at least on my car). There are a lot of people that have this same problem. Hopefully someone out there has figured out the problem!?

 

Do you have any check engine codes? If not id say your problem is somewhere between the buffer box and the gauge with the gauge possibly being faulty. If you do the wire going to the buffer box(behind the dash) is probably broken.

 

Not familiar with how to determine if there are any check codes? How do I do that? I had the cluster out at one time before I knew it didn't have a speedometer cable in it. Where is the buffer box located?

Many thanks for the response.

 

well is your check engine light on at all? also you can jumper two terminals in your ALDL to pull the codes.

 

My Service Engine Soon light stays on most all the time. As far as I know I don't have a Check Engine light.

What is the ALDL? I am unfamiliar with the term.


Thanks.

 

The check engine and service engine soon are the same thing.

Aldl stands for assembly line diagnostic link. It is what technicians use to get codes and info from your car. Its next to your fuse panel.

Since your check engine light is on theres probably something wrong with the connector at the sensor or the wire coming off it.

 

first thing i would do would be to hook a scan tool/laptop up to the car and drive it.

if the ECM is seeing the speed, then the speedo, ECM VSS buffer, or wiring between the two is the problem.

if the ECM sees nothign, then it is the wiring or the VSS itself.

 

My VSS on my 91 camaro does the same thing except when the car is cold my speedo wont work at all but after 15 miles of driving it suddenly works. I checked the connections and they seem fine so i was going to replace the VSS but now that i see someone has replaced theirs and had no good results i think i might hold off. My car does not throw out any SES codes either which i find werid.

 

My speedometer used to work after driving for a while also but it gradually got worse to the point of it never comes on now. I wouldn't by the VSS just yet, I replaced mine this past weekend and still don't have a working speedometer.. Was really disappointed...

 

I had a similar problem to what you guys have been talking about a couple of times. In my case the problem was a blown piece of circuitry on the back of the cluster. I would suggest pulling it out and taking it apart. If you see any black marks, it's a good sign that that is the component that needs to be replaced. In my case there is a shop by me that does nothing but service gauge clusters. If you call your local dealer they can probably turn you to somebody who can test/fix it for you


Here's the shop info if you want to give them a call

Model Electronics Inc
(845)623-8020

 

I had my guage cluster out when i replaced a light bulb but everything looked fine this was about 2 months ago how ever i had to take the beep speaker out becasue when ever my car was on and i would turn on the head lights it would beep.

 

MrDude_1

How do I go about hooking a laptop up to my car? Is the information on how to do that here somewhere?

Thanks

 

MY stories pretty similar. My speedo wouldn;'t work for the first few miles of driving, expecially when cold, and then after drivnign for a little it would jump up. I ended up replacing the VSS and for a few days it worked then quite. I had to have the tranny fluid changed so i took it to the dealer, my mom paid b/c she's afraid i'lll ruin her driveway.... (what else is a driveway for that to catch car fluid?) Well I had the dealership (never trust pepboys, spend the money and take it to the dealer to know that they know the car. Heck, they only work on Chevy's right?) take a look at thespeedo problem, turns out that National Auto sold me the wrong VSS sensor. They put in a GM one and haven't had a problem in the 2 months since then. Sadly, by the time i had the problem fixed i had waster my money on the other VSS b/c i had lost the box, oh well....

Just a little advice to check out.

As for the laptop and ALDL thing, look around a little for it, there is plenty out there and it's a great tool to have. search on google or yahoo for WinALDL and you can log all your data from your ECM.

Also a little note is that i have the same car tlgrooms (chevy must have dropped the ball on the VSS that year....)

 

Does anyone have info on the ALDL cable for the '91? Will a straight cable hookup work or does it need resistors installed?

Thanks for any help..

Tim

 

no resistors... just one pin on the data terminal, and one for ground......

the simple single resistor cable works great.

 

Finally built my cable and got it hooked up. Here's what I have under error codes:

13 Oxygen Sensor
22 TPS Low
24 VSS

Can anyone tell me what these mean? Does the VSS error code mean it is definately a problem with the VSS itself or could it still be because of wiring?

The VSS I bought did not have the exact same number on it as the one I took off of my car but it was real close and looked the same. I was assured by the guy it was the right one. Now I'm not so sure.

Many thanks for the help,
Tim

 

i have the same exact problem and car...the speedo hasn't worked since i got the car. my tach worked but was way off for about 2 months and then that stopped working. i also replaced the VSS and no change. i am thinking about just buying another gauge cluster off ebay but im worried that one will go to hell too.

 

Going to replace my oxygen sensor tomorrow so figured that out. Can anyone tell me what the tps low error means?

 

Replaced my oxygen sensor today and disconnected the battery and reconnected and all my error codes are gone now including the VSS error. Does anyone know if this means my speedometer problem is definately in the wiring?

I am still not getting a reading from the ALDL program for speed.

Tim

 

Did you drive your car after you disconnected the batter? There can only be a vss code if you attemp to drive the car. The code going aways doesnt tell you where the problem is.

 

Yes, shut the program down and restarted and drove the car a couple of miles. It isn't showing any error codes now. Still shows 0 on the MPH settings.

 

Got hold of another VSS, a new one this time that I am sure is the correct VSS for my car and speedometer still doesn't work. Can anyone tell me if the wire going to the VSS is hooked up to another else or does it go straight to the ECM? Where is the ECM located on a '91 and how do I identify the wire coming from the VSS?