Fixing a wiring problem

The signal wire for my oil pressure gauge has some sort of issue. I figured this out by connecting the gauge directly to the sender with a long run of speaker wire - everything else in the dash remained the same, just the one wire difference. What happens with the faulty wire is that after the car is warm, the gauge needle will start dancing around in a certain zone, indicating a varying level of resistance in the wire. I cannot replicate this by shaking the wire in the engine bay with the car parked. I'll check again, but there are no visible faults in the bit I can see in the engine bay.

So I have one bad wire between the engine and the gauge cluster. I don't know which part of this wire is bad. How would you go about fixing this? Pull the dash, replace the entire run? Snip, replace, crimp, hope you've removed the faulty bit?

Go go gadget hive mind!

Unhook original. Run new along the bundle. Rewrap with split loom. Forget it ever happened.

^^ Yup, that's it. Solder and heat-shrink tubing, I might add. Heat is resistance, you have a crappy connection somewhere that's ok when it's cold. Heat is adding resistance.

It is very likely at an end or a connection. If it were me I would take a bit off both ends and see if that fixes it, at least it's a quick test if it doesn't work.

Dusterbd13 wrote: Unhook original. Run new along the bundle. Rewrap with split loom. Forget it ever happened.

This. I frequently run new ABS speed sensor wires from front to back on JK Wranglers.

If you want to leave as much OE wiring as possible, cut it at the halfway mark(probably firewall area?) and run new wire temporarily on half to see if it still exists. It will at least cut the searching area down by 50%. Or just replace half depending on how much of a pain it is.