Chevy 84 s10

You need to find the ground wire that goes to your dash instrument panel. There is a ground wire that is lose or broken Make sure that all the ground wires are clean and tight.You could try to run a ground wire from your panel to a good ground place. ( This always don't work) but I have done it like this before and worked great. It is only a quick fix, It should be done right. But make sure that you have a really good ground on both the metal panel and metal on your firewall.