Speedometer and Odometer not Working
Thread Starter
Teching In
Joined: Mar 2019
Posts: 39
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From: Dallas TX
Speedometer and Odometer not Working Okay guys, I’ve searched the form and found two fixes for the odometer and speedometer not working. One was to make a new harness from two pins 20 and 21 going directly to the VSS, and the other was some wires were loose by the gear shift and moving random parts in the area solved one guys issue.
My issue is I can see mph on the scan tool while driving but my instrument cluster doesn’t give a reading at the cluster, Also I have replaced it with a know good cluster and new VSS.
Then I pulled the connector and harness behind the cluster and checked continuity to the wire that comes from the pcm to cluster for speed, I forget what terminal but I have continuity there. I need some guidance where to go from this point.
I’m thinking pcm and abs. My abs light is on and the cruise doesn’t work. So I will work to fix those issues although I don’t think they are related. Any help would be much appreciated!
1998 Trans Am
5.7 LS1 A4
Purchased with the MPH and Cruise inoperable.
My issue is I can see mph on the scan tool while driving but my instrument cluster doesn’t give a reading at the cluster, Also I have replaced it with a know good cluster and new VSS.
Then I pulled the connector and harness behind the cluster and checked continuity to the wire that comes from the pcm to cluster for speed, I forget what terminal but I have continuity there. I need some guidance where to go from this point.
I’m thinking pcm and abs. My abs light is on and the cruise doesn’t work. So I will work to fix those issues although I don’t think they are related. Any help would be much appreciated!
1998 Trans Am
5.7 LS1 A4
Purchased with the MPH and Cruise inoperable.
Last edited by Bmoore34; May 24, 2020 at 05:56 PM. Reason: Updating Information
Before we chase after this with you, can you please tell us more about the car? That model car is it? What engine?
Is this car new to you? Did you get it with this problem? Was it fine and then did this start all of a sudden? Did this problem start after you performed another repair?
Then the easy stuff:
- Did you check the gauge and cluster fuses?
What does this mean? Did you put in the new cluster because this is what you were doing? Did the old cluster work or did you try this in an effort to chase the problem? Is this a change you made that started the problem?
Is this car new to you? Did you get it with this problem? Was it fine and then did this start all of a sudden? Did this problem start after you performed another repair?
Then the easy stuff:
- Did you check the gauge and cluster fuses?
What does this mean? Did you put in the new cluster because this is what you were doing? Did the old cluster work or did you try this in an effort to chase the problem? Is this a change you made that started the problem?
Thread Starter
Teching In
Joined: Mar 2019
Posts: 39
Likes: 0
From: Dallas TX
After finding a repair guide I placed a test light on the wire coming from the PCM to the cluster (vss signal wire out) and drove the car. The light never flashed/pulsed.
Next I ordered a new PCM taking a chance, installed it and all works well. So the issue was the original PCM driver for the MPH must have been bad.
Next I ordered a new PCM taking a chance, installed it and all works well. So the issue was the original PCM driver for the MPH must have been bad.
Teching In
Joined: Aug 2024
Posts: 2
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How did you go about getting the replacement PCM? Did you buy it online and program it to your vin yourself? I'm having the same issue but my speed is not being shown on the cluster or in the computer. I've replaced the sensor and checked all wiring going to the pcm/cluster everything seems okay, so I'm leaning toward a bad PCM. I'm not able to find much online about replacements or reprogramming. 99 camaro ss fyi
Joined: Nov 2003
Posts: 11,328
Likes: 346
From: Jacksonville, FL (originally from Toronto Canada)
