Ye olde wiring harness? When to replace?

The rule of thumb is the same with all electronics:

How much smoke got out of them?


You see, electronics run on smoke. It is inside them. The electrons transfer the smoke throughout the component and that's what makes if function. If you let out too much smoke from the electronic component, then it won't work anymore. It's like blood, if you loose too much, you die. Same with electronics & wiring, if you let all of the smoke out of them, they die....