How do you get to the back of the speedometer? Mine works sometimes and then it doesnt so i wanted to check all connections. I kinda tried just to pull the front off but my light switch handle wont come off. Its in a 91 z28

 

are you talking about removing the speedo from the cluster or removing the cluster itself? and also what light switch handle maybe my 84 is different but i have no light switch even close to my speedo

 

nvm i figured it out thanks for the response tho, now i just need to know why the spedometer works when the car has been running for a long time but not when its cold? I took the cluster out and everything checks out back there whats next??

 

if the speedo is fine you should probably check the tranny or take the cable off and see if it spins when cold

 

i think its an electric speedo if not mistaken

 

im not to familier with electric speedos but ill try to help anyway, where is it connected to gets its speed reading? because if it only works when the engine is warm then theres probably something loose or possibly worn that expands when it gets warmer causing your speedo to start working.

 

yeah dspencer24 you are correct,if the car is a 91 the speedo is def. electronic.Other than the cluster itself,the only thing I can think of is maybe the speed sensor in the trans. Maybe just check and make sure you have good connections and all of the harness terminals are clean.When you pull the connectors out I found it to be good practice to put some dielectric grease on the terminal ends before plugging them back in.Hopefully that will fix your problem.I currently need a new speed sensor on my car.Maybe I'll get it this week,not sure yet though.Anyway,good luck with that

 

why not stick a voltmeter on the connectors to see if they are giving out a signal? im assuming they would even tho the car isnt moving

 

there would be no signal unless the VSS was spinning... on the 91 IIRC its a hall effect sender and creates its own voltage based on how fast you are going... also i think it makes a sine wave so you'd need a o-scope to check it properly

 

thanks for the help i fixed it i cleaned the chip thats inside the speedo and then put it back and now it works

 

i wasent saying check out exactly whas going on in the signal i was just saying to see if it was there, not everyone has an osciloscope