When I turn the ignition on the gas gauge goes down?

Is the battery in good condition, does the engine start and run? If so, it sounds like the cluster is going out.

Here is a video to show you how to fix the problem:

https://youtu.be/_HEC44xENxw

Please let us know if you need anything else to get the problem fixed.

The battery is not the best, but when the issue was occurring with the cluster, it was starting with no problem.

someone had mentioned that it might be a grounding wire issue.. might that be the case?

Yes, that is possible, here is the wiring diagram so you can see which wire is for ground, remove the connector from the cluster before you run the test by following this guide.

https://www.2carpros.com/articles/how-to-use-a-test-light-circuit-tester

It is a blk/wt wire if is okay replace the cluster to fix the problem. Check out the images (below). Please let us know what happens.

i put a different cluster in to see if my cluster was bad and the other cluster did the same thing. The battery is fine. It starts every time.

Okay, then we are back to testing the power and ground for the cluster. Also please check the main body ground from the battery to the body/frame.

When i turn the ignition/key on the gas gauge goes down. When i turn the ignition/key off, the gas gauge goes up and the speedometer goes up a bit.

This happens when the cluster is going out, I would search Ebay or Google for a rebuilt unit.

Here is a video to show you how to do the job:

https://youtu.be/_HEC44xENxw

Please go over this guide and get back to us.

i put a different cluster in and that cluster did the same exact thing.

i was told that it might be a ground wire issue, but i am having a very difficult time finding where the ground wire is and where it is grounded at. Assistance please.

The ground is behind the instrument cluster on the main bulkhead.

Ken, could you please be a bit more specific with where the ground is for the cluster?

Yes, the ground completes the circuit for the instruments inside the cluster. Check out the wiring diagrams in the post above.

Ken..I understand that, but i can't find where the ground is ...tried tracking it from behind the cluster but i cant find where it goes to. i can see where the ground is and where it goes on the diagram, but i can't find where it actually is on the truck

They don't give the ground locations exactly. You can test the ground by using this guide:

https://www.2carpros.com/articles/how-to-use-a-test-light-circuit-tester

Please go over this guide and get back to us.

sorry to bother you Ken, but i am completely naive as to how to go about testing the ground. i looked at the link you sent and i still don't understand. could you please break it down more simply for me. i'd sure appreciate it

Sure, if you attach the test light to the positive side of the battery it now tests ground circuits. You will need a test light with a long lead or just make an extension from extra wire. Use the wiring diagrams above to see which wires go to ground which are the wires headed downward with the three little lines at the end. Let me know,