I have an 87 Formula 350 and my 140mph speedo is not working. I bought the car in this condition, so I basically have no clue why it went or what caused it to stop working. What are some common problems, so I can look into fixing this ASAP? I'd love to go to the junk yard and find what I need.

 

im not sure if thats electric speedo or cable drivin unit.. u might have to check ur RPO codes. but either way its probably the speedo gears in the tail end of ur tranny. they are probably stripped, its the most common problem. sorry i can't be much more help but its some information, i can have more tomorrow where i can take pics and stuff and do more research, but by then someone else will probably take over... do u have cruise control?

 

Thanks for the reply. I don't have cruise control and I know that pontiac used electronic speedo's, so maybe that will be some assistance to you. I'd love to solve this problem, cause it's a major inconvinience with the ammount of police around my area.

 

All firebirds models had electronic speedos '87 (or '86????) up. Are you getting a check engine light? If you are, the culprit could be the VSS...thats where the speedo and the ECM get the speed information. If you aren't, i'd take out the cluster and make sure all the contacts are good.

 

Thanks for the help. I'm not getting a check engine light, so I'll tear apart the dash and check everything out. If it does end up being the VSS module, do I need to find one from a car with the same speedo (140mph) or will any do? According to the original owner, it went out during a rather spirited highway drive, but that is all I know. Don't know if that helps at all.

 

You can use the same VSS from any firebird that has an electronic speedo. All of the speedos in 'birds are calibrated to work with the same VSS. If your computer isn't throwing a code, its getting pulses from the VSS which means the VSS is ok.

 

Thank you very much for your help. I'll check out all the connections and see where the problem lies. Anything/anywhere I should particularly look other than just behind the cluster?