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Randy, Computer Technician
Category: Chevy
Satisfied Customers: 9756
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My speedometer doesn't work. It worked before the computer went

Customer Question

My speedometer doesn't work. It worked before the computer went bad. what else could be wrong? Don't know what else to replace.
Submitted: 2 years ago.
Category: Chevy
Expert:  Randy replied 2 years ago.
Hi, my name is ***** ***** certified automotive professional with over 25 years experience. I will be glad to assist you with this.This sounds like it may be in the wiring, I have included the wiring schematic for you to use and check. If the vehicle is shifting correctly that means the PCM is receiving the correct signal. If you are sure the speedometer is good then it has to e between the PCM and the speedometer. Check the dark green wire from pin 13 on the PCM C1 connector all the way to the speedometer connector. You can use a multi-meter and set oms to check for continuity.
Expert:  Randy replied 2 years ago.
Customer: replied 2 years ago.
Randy, I found the #13 dark green wire and traced it through the large connector on the firewall by the right shock tower. From the inside of the car I traced it to the radio. I thought, this can't be right. I went back to the PCM and found another dark green wire also in another #13 location! Tried to trace that one. It doesn't seem to go to the large connector. I tried tracing the dark green wire back from the T1 terminal on the speedo cluster and I got as far as a white connector with: red/wht, yel, dk/grn, blk, blk. Not sure where they go from there. This car was built in Canada if that helps. Here's the VIN: 2G1WL52M7V9114405. Any other wiring diagrams that might help?
Customer: replied 2 years ago.
Randy, there are two connectors on the PCM. One is clear and one is blue. which one is the C1 ?
Customer: replied 2 years ago.
I got your email asking me to rate you. I'm not done yet. I still need answers to the above questions. Please respond.
Expert:  Randy replied 2 years ago.
sorry about the emails and the delay getting back to you, they are sent automatically to be sure that you are satisfied.
Use a multimeter to ohm out the dark green wire in the diagram, from the computer C1 pin number 13 to the ip harness on the right side of the knee bolster. Make sure that it is not broken.
Customer: replied 2 years ago.
There are 2 # ***** pins with a dark green wire. Which one is the one that goes to the speedometer? You said the one from the computer C1. Which wire harness on the computer is the C1? There are 2. One blue and one clear connection'
Expert:  Randy replied 2 years ago.
Have you checked the number 25 fuse(5amp) located in instrument panel end on passenger side.
Customer: replied 2 years ago.
This car doesn't take a fuse in #25 receptical, it's blank. In that row they only go from 19 through 23. Can you find a detailed schematic from computer vss out to speedometer cluster that might help?