Strange Electrical Problem

The reverse lights sounds like a short to the power from the rest of your lighting in the harness. The stalling is probably not related to using your brakes, its probably just an idle related problem.

There was a very recent thread like this - get with that guy (unless it was you) and see what he found.

I agree that the harness wiring is crosswired or shorted together at some point. It takes some hunting to find the source though.

Good luck.

DJFox said:

what guy was this. Do you recall his name at all?

Click to expand...

I just searched for you and apparently it was your thread .
I remember issues that arise but not always who posts them. I didn't realize you had started two nearly identical threads.

Good luck.

Im saying vacumm problem maybe for your brakes..

There are no clues if your car is 5 speed or auto. That's why it is a good idea to use the sig under the user control panel (User CP) option. It allows you to post your car year & mods, which help greatly when troubleshooting things. No, it is not there for us to snoop and see any "Secrets" you have hidden away under the hood. Be a good stangnetter and update you sig for future reference & don't keep us guessing.

Get a good DVM and check the voltage when you step on the brakes at idle. Put the trans
in neutral and try it to see if it still happens. If it still does, look for things like underdrive
pulleys, or maybe a weak alternator. If the electrical holds good at 12 volts or more, then
look for a vacuum leak. If you can’t hold 12 volts at idle then you either have a
bad/missing ground or bad alternator. The secondary power ground is between the
back of the intake manifold and the driver's side firewall. It is often missing or
loose. It supplies ground for the alternator, A/C compressor clutch and other electrical
accessories such as the gauges. Do not say "it's just a ground, it really isn't needed". Grounds in automotive circuits are the return path for power. No good ground, no properly functioning circuit.

Diagram courtesy of Tmoss & Stang&2birds: it for an 88, but the 90 model is the same except for the MAP sensor vacuum line. The MAP sensor is not connected on the 90 model cars.


Use a vacuum gauge to check vacuum at idle in neutral, you should see 16”-19” of
vacuum. Less than that is cause to suspect a vacuum leak. Check the vacuum lines, the
hard plastic lines often crack at the ends and leak. The rubber grommet that holds the
vacuum supply check valve in the brake booster is a known problem.


See the following website for some help from Tmoss (diagram designer) & Stang&2Birds (website host) for help on 88-95 wiring http://www.veryuseful.com/mustang/tech/engine/

http://www.veryuseful.com/mustang/tech/engine/images/IgnitionSwitchWiring.gif

http://www.veryuseful.com/mustang/tech/engine/images/fuel-alt-links-ign-ac.gif

http://www.veryuseful.com/mustang/tech/engine/images/88-91_5.0_EEC_Wiring_Diagram.gif