Wiring Issues - Gauges, Blower, Turn Signals

[very fat and very dumb 40]

None of them work, I've searched and read the old posts. When I tested for continuity between the negative post on the battery to the firewall ground wire it was good. I then checked and everything worked fine. I'll have to wait for it to happen again before I can troubleshoot it.

My question is, what is the common ground between the turn signals, blower motor and gauges?

I will tell you I have the blower motor and firewall ground on the same bolt in the firewall. Maybe I just answered my own question. What do you guys think?

[LindenBruce 27]

The engine was ground to the firewall. I have seen the blower motor grounded to the firewall or the rear passenger side fender apron on non A/C cars. Signals and gauges I don't remember were. Have you checked the connector behind your fuse block? That's a common area for corrosion. Bruce

[cst 13]

just had same problem with turn signals and gauges, after weeks of headaches it was something as simple as sanding the terminals at the fusebox! Also had all gauges not reading it was the black wire with the violet resistance wire i mistaken it for a ground, also the post on my gauges were touching the housing

the black wire is for some kind of testing purposes. Wiring kicked my ass ! I I bought a parts harness of flea bay for 40 dollars because my ignition switch connection was melted on both sides and also replaced my ignition switch. A good source for a turn signal switch is Auto part sales in Colorado mfg. by shee-mar( american made) for $72.80 every one else wants over $100 for chinese crap. THis is for a 1970 Mach 1. PS my buddy just put a tranny in a Toyota Solera to save over $500 in labor.

[Lemon Owner 11]

If all the correct wires are connected I would as the others said sand the fuse posts and terminals in the fuse box. I had the same problem which that solved.

[very fat and very dumb 40]

Since I live in a wet version of hell I have not been able to drive the Mustang for 2 months. We had a rare dry day yesterday and took the car for a drive. I had the same issue, while the engine was running I moved the key slightly to the left and the gauges started working. Perhaps a failing ignition switch makes odd things happen just like a failing headlight switch does. I thought I would throw this out there. I'd be curious to know if anyone has success from this.