98 gmc sonoma stereo/speedometer?

 I Have a 98 GMC sonoma and I  installed a deck. I dont know what happened but after installing the unit my speedometer stopped working and I dont know what to do! Does the stereo wiring have anything to do with it? Or could it be a fuse. If you can help please do.....

(confused) unless your speedometer is digital. your stereo prolly has nothing to do with it...you prolly bumped something while installing the stereo. like the power wire. take it to a mechanic or somewhere and have them check it..or if you have friends that know this kinda stuff have them check it..that way you dont have to pay cash just for looking it over.

There is a GREEN / WHITE wire at the radio's plug. This is the vehicle's speed sensor circuit. Make sure that it is not connected to anything and should be taped off so it won't ground out. This is probably your problem.sparky

It is possible you have caused damage to one of the units in the speedometer circuit if yu shorted it to a ground or power wire. If you have a meter set it on an A/C voltage scale and measure between the GREEN / WHITE and ground to see if you get a reading that varies with speed. You should. ou can also try your factory cruise control if your truck is so equipped. If it works OK then the problem may be in your instrument clustre. The factory cruise uses the GREEN / WHITE for vehicle speed and if it sets OK then your engine's computer (PCM) should be OK.sparky

WHy did they put a speed sensor wire in the radio plug? Just curious. Thanks!Tim-May!

I think I just answered my own question :) I think it is for the auto volume feature with the speed of the car.Tim-May!

thanks sparkie,   But today I found out that my speedometer only works during the day, my headlights are automatic, and when they come on when it gets dark my speedometer stops working, so I m thinking i might have my Illum wire or Dimmer wire connected wrong, what do you think?

I think you may be correct. There is a dark brown and a gray wire at the radio for the lamp circuits. Make sure you haven't tapped into these wires for ground or speakers. Only use the brown if your radio has a illumination wire. The vehicle speed sensor wire is for the radio's speed control volume circuit. As the vehicle speed increases so does the factory radio's volume. sparky