About 50% of the time either my speedometer and or my tachometer do not work. They just stay at zero. Sometimes it's only one of them, other times it's both.

Is there a common part that might need to be replaced that handles both of these?

 

Read these from other forums;

-Try holding the trip button (the one next to your odometer) for a few second, turn the key to the on position (dont start the truck yet)...it should reset the tach & speedo.

-Put the truck in reverse then try to start it 3 times...(I don't see how that one worked?)

-Manually move the needles on the tach and speedo then start the truck.

 

That one of the symptoms of a bad sensor/plug that goes on top of the rear diff pumpkin...damn, it's on the tip of my tongue and I know what it's called!!!

 

Thanks for the replies.

J4- If you think of the name please let me know. Is it something that is known for sometimes working and sometimes not? Seems weird to me. I would think it would either be good or bad.

 

Yes, it's pretty common. It'll also cause your ABS/Brake light to turn on.
AAHHHHAA!!!! It's called the ABS speed sensor. It's located on top of the rear diff like I said before. It counts the revolutions of the diff and translates that into MPH. I'm 99% sure that's you problem. Just make sure you check the obvious first such as wires, cables and anything that's loose.

 

That would be the rear wheel speed sensor, but, that shouldn't affect the tach. Wonder if you have a loose connection somewhere....

 

Don't know why, but autozone and Advanced auto has it labeled as ABS speed sensor. I've read that it could cause your speedo and tach not to work. Could be wrong though. To the OP, take HeyYou's word over mine. He know's his stuff.

 

Since I am clueless, where would I begin to start checking for a loose connection? Remove the instrument panel where the speedometer is?

 

The name for that sensor varies by who makes it I think. (and sometimes by who is asking.....)

I think the cluster plugs into a socket held in place by the main part of the dash. I haven't had mine apart yet...... (thank god) to know for sure. You may also want to check the connectors at the PCM, they sometimes like to corrode, and give you some truly odd behavior.