Whats this mystery wire do ?

[5ohjoe87]

Ok guys, On my 1987 mustang gt there is a small black wire that shares a connection to the negative battery terminal what does it do for the car . My 1990 has the same wire. The wire also shares a ground with some sort of two piece snap together connector that is grounded to the chasiss . The connector has a black with green strip on its wire. The stinky little black wire melted on me today . I ran the car fine without this wire connected for awile after i re connected it back up the car will not start up again if i remove the little black wire . I noticed that the car will not start the dome light is dimmer now and the power door locks along with the window motors do not work if i remove the small black wire. I had this wire disconnected before around 2 months and never had any problems. I AM ON MY 3RD OPTIMA BATTERY. The cars battery will discharge in one day also.

 

[jerryD]

i can't see the pic, but i would guess that it is the frame ground.

 

[5ohjoe87]

I am sorry i could not figure out how to upload the picture. ITs the small black wire that attatches onto the battery terminal with the big negative battery cable Why would this ground be important?

 

[DouglasOhio]

The black plastic connector that shares the ground with the black wire that connects to the batter is the main computer ground. Maybe that isnt a good enough ground and is causing the problems you say you have. Maybe when your black wire melted you didnt get a good ground when you reconnected the computer ground and its effing up...
good luck. I know how you feel

 

[cjman15]

Yeah, it's just a ground, could probably crimp a new terminal ring on it and reconnect it.

 

[mjbtv]

If the ground melted then who hooked up the battery backwards? And If you did hook the battery up backwards, kiss the computer goodbye.

 

[HISSIN50]

The black plastic connector that shares the ground with the black wire that connects to the batter is the main computer ground.

from what you said, I agree with Douglas. the stock one will have a small plastic deal just off the ring terminal a few inches (looks like an old inline fuse holder for glass fuses).

good luck.

 

[5ohjoe87]

Thanks I never would have thought ford would ground the computer in that location. I replaced the wire and added a battery cutoff knob to the negative post. Is there any issues with disconecting the battery with a cut off knob since the computer memory will clear ? The car is my second vehicle and sits about 4 days a week.

 

[blown1989saleen]

sounds like the EEC ground

 

[HISSIN50]

i see no issues with a battery cut off, myself. you will just have to let the puter adapt again upon hooking it up.

you could hook up a trickle charger. I made a dealie for 2 bucks where i can hook up a 9 volt battery into the cig lighter. it works as long as you dont have a short (which toasts the 9 volt battery quick).

 

[DMAN302]

If the ground melted then who hooked up the battery backwards? And If you did hook the battery up backwards, kiss the computer goodbye.

Actually did this once..the computer did survive ..the TFI and headlight switch did not...

 

[HISSIN50]

the puter is supposed to be able to survive a double-voltage reverse polarity hook up, IIRC.