Speedometer Not Working Help
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Joined: Dec 2017
Posts: 54
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Speedometer Not Working Help
So I have zero speedometer in my 08 base M6 car. It works fine if I use the Tech 2 via the cluster options. And all 4 wheel speed sensors are good. I used the Tech 2 to monitor the sensors and all show speed. What else could be the issue? Could it be the VSS on the top of the differential? Whoever owned the car prior had replaced the clutch. Wondering if they either forgot to plug it back in or it got damaged. From what I see in the schematics it appears to go straight into the ECM from the diff. But I also notice that in the radio schematics the drk/grn white wire runs from ECM through the radio to the gauges. I heard this can also be an issue. But if that was bad would the gauge work via the Tech 2? They put in an aftermarket radio reason I mentioned it. Just not sure what I should be checking other than those. If anyone can help it would be greatly appreciated. I need to get this car inspected and that’s my last hurdle.
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Joined: Dec 2017
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Was you able to change that without removing anything? Problem I have is the prior owner put Z06 exhaust on here and it’s all welded from x-pipe to muffler. And I can’t get it out of the way unless I cut it. I can just barely get my hand on the sensor. I’m wonder if I can drop the cradle enough to get it out.
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Joined: Dec 2013
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Put a tech II on the car, go to BCM data, and look at the speedo reading as you drive the car.
If the VSS is starting to go out, will not see a reading on the BCM data for vehicle speed until you get to about 10mph, then will do a major jump to correct mileage.
If no reading at all, check the VSS connector to make sure is not unplugged, or that you have a wiring problem.
as show above, it not hard to get to the VSS blindly, since you do have the room between the top of the dif and the bottom of the car.
If BCM is showing the correct mileage cleanly with no intial starting jumps, then problem is not the VSS, but in the IPC/its connector or wiring instead.
Thread Starter
Advanced
Joined: Dec 2017
Posts: 54
Likes: 4
Put a tech II on the car, go to BCM data, and look at the speedo reading as you drive the car.
If the VSS is starting to go out, will not see a reading on the BCM data for vehicle speed until you get to about 10mph, then will do a major jump to correct mileage.
If no reading at all, check the VSS connector to make sure is not unplugged, or that you have a wiring problem.
as show above, it not hard to get to the VSS blindly, since you do have the room between the top of the dif and the bottom of the car.
If BCM is showing the correct mileage cleanly with no intial starting jumps, then problem is not the VSS, but in the IPC/its connector or wiring instead.
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