Wiring Issues ARGH!! There's a short somewhere! Lots of things stop working...

[ShannonT]

Ok, here's the details on the car...

1989 Mustang GT 5.0 Convertible 5 Speed - BONE STOCK

Periodically, the majority of the electrical system quits working. Turn Signals, Backup Lights, Blower for Heater/air, motor for conv top, and the freaking 'check oil' light comes on.

Guages work fine, nothing unusual, except the check oil light.

Here's the strange part: Sometimes when I put the clutch in, everything starts working correctly, but while driving, when I hit the brake and decelerate quickly, it starts up again. all of the affected items have fuses within close proximity and that makes me think it's a short, but moving the wires back and forth without pressing the clutch does nothing. By nothing, I mean it doesn't cause the problem to begin occurring when it is operating correctly, nor does it fix the problem if it is operating incorrectly

Braking is not the only time this issue occurs. Sometimes after running 'normal,' when I start it again, the issue resurfaces.

This whole thing started today, and the first issue, that has not resurfaced, was the clutch switch. I had the clutch to the floor and it wouldn't crank. My 15 year old being sarcastic went out to try it and it cranked first try and fired. (Remind me to shoot him later) After he started it, the issue has not resurfaced at all.

I am hoping someone else has experienced this issue, or knows of a potential cause to affect so many items at the same time, because I am about ready to claim it stolen, drive it off a cliff, and buy another one with the insurance money!

Any help would be GREATLY appreciated!

Shannon T.

 

[88mouse]

Sounds like you have a bad ground on the dash. There is one on the back side of the dash in the middle. Check in and the ground that goes from the fire wall to the back of the head on the driver side.

 

[ShannonT]

Can you be more specific with the location on the ground on the backside of the dash?

I don't mean to sound dumb, but my last project was a 67 fastback. I've only had this for a few months, and haven't taken it apart yet.

Your reply indicated there is a ground on the backside of the dash in the middle. Is it behind the stereo and A/C controls? or middle of the driver's side? Can you ID something that is close to it, so I can use it for general reference?

For example, the heater core is toward the right of the center of the dash, just to the left of the glove box.

Thanks for the help! I really appreciate it!

 

[88mouse]

Its around the a/c controls. Its a small black wire that ground to the frame of the dash.

You may have a hard time geting to it.

 

[speedytang]

Also a ground braided wire that runs to a stud/bolt by your feet by the steering and brake pedal assy. This sounds like your problem and your hitting it when pushing the brake or clutch.

 

[HISSIN50]

Your ignition switch might be on the outs. I would swap it as part of preventative maintenance (20 bucks for a new Ford version at the dealer). While in there, inspect the wires to the switch (they can melt as the switch fails).

Good luck.

 

[jrichker]

Another vote for the ignition switch. There was a recall on them since the tend to overheat and catch fire.

The only singe ground that would disable all the things you mentioned is the battery to chassis pigtail ground. It is very unlikely that any single ground inside the car is causing your problem.