Speedometer Issue

I haven't found anything about this issue.

When the speedometer stopped working, prior to passing 200K, it always stays at 40 mph when not driving. When I begin driving the needle moves up way past the speed I am at and eventually pegs itself although I am driving far slower.

The engine light is not on, the odometer and cruise control both work. I went by a parts store and asked them to do a scan but without an engine light being on they would not scan it.

Any thoughts?

 

To throw this in, yesterday I replaced the speed sensor on the transmission and when I disconnected the plug and removed the sensor, the speedometer needle stayed on 40 mph. Installing the new one and plugging it in did not change anything either. I'm still researching.

 

Sounds like a bad cluster. I'm gonna guess that 4th gen is a combo of analog Guages and a circuit board. Guessing that since you said unplugging it still has no difference. It's not going to be an ECU issue, so no check engine light will pop. (Ironic, the thing to tell you other things are bad in the truck won't tell you when itself is bad. Lol)

Easiest way.....find another one in a junk yard or ebay.

Otherwise you're tracking down a blown capacitor, chip, resistor, etc.

 

Could a bad wheel speed sensor cause this? I think that would pop a code though yeah?

 

that issue SHOULD pop a CEL. BUT, in this particular situation who knows if it did or not.

And with the truck off and cluster unplugged, it had no change. Nothing went back to 0.

 

Just read this reply ^. The speedometer cluster was not unplugged, just the plug that went on the sensor going into the transmission. That is going to be the next thing I do, when I can dive into the dash. I'm thinking of options for that.

 

10-4 but either way, when you unplugged the sensor SOMETHING shoulda happened. some sort of reaction from above.

If you have alerts set up on something (CEL in this case), you expect to get that alert whether it's unplugged from the attachment on either end. Otherwise, move up to the next step where that alert would come from (instrument cluster). And that is the common denominator between the sensor and the needle not going to 0.

 

Makes sense, thank you!