Speedometer

[wjsmith]

Why would my speedometer not start reading until I'm up to about 40-50 mph but only reading 20

[newdude]

What year truck?

[wjsmith]

92 cheyenne

[Jsdirt]

If it's got a cable, it needs some lube BAD. Might have a stripped plastic drive in the tranny or transfer case from it. Check all the above. Might even help to put a little shot of lube in the back of the speedo housing where the cable enters as well.

[Doug_Scott]

Not sure what end the inner cable comes out of for lubing, but, I would first check the transmission end of the cable, disconnect the cable, and see if you can pull the inner cable out of the cable. If it does not come out there, then you will have to disconnect cable from instrument cluster, and then pull the inner cable out. Once it is out, take cable off of transmission again, and spray some light lubricant down the outer casing of the speedo cable. Due to needing to work in below zero temps, any oil will likely cause issues on very cold days when lubricant thickens up. ATF is good to use, just put the inner cable into a container that has some ATF in it.

[wjsmith]

All I have is a sensor there is no cable on transmission or the back of cluster. I replaced sensor and still not working correctly.

[bjd2014lt]

Also check engine grounds i had an 88 do that but also had other gauges fluctuating as well

[Doug_Scott]

Verify all wiring connections in the speedo circuit as well as ground connections. You will likely have to locate instructions on how to test speedometer head itself.