So I am new to fords and I got an 89' 351w as a beater truck for 700 bucks and am currently fixing it up. The way this ground is coming off of the battery is weird though, I'm almost thinking it's supposed to be on the positive terminal but it was this was when I bought it. Anyone have a 351 or 302 I can cross reference this plug to?

 

A picture would help a lot.

 

This is the plug I am talking about.
Sorry for some reason I couldn't upload it till now.

 

I suggest you take of the tape and verify the wire colors.

If your truck is still EFI, one of those wires might be the ground for the Engine Computer.
The other wire could be for the Body, Alternator or Headlamp Grounds.

You could disconnect the plus and see what stops working.

Make sure you have a Ground Strap from your Engine to the Body/Firewall.


When you are done messing with the connections, I suggest you spray the terminals and exposed wires with a battery spray protector.
Those clamp style connections corrode sooner than later.

Nice Battery....

 

One of the wires go to the EEC Computer ground and the other goes to ERBP (see below diagram).



ERBP: Electronic Rear Brake Proportioning (Anti-Lock Brakes Proportioning Valve ground)
/

 

I have an 89 F150 and I have the same ground plug. Don’t know what it is but it’s always been there and everything works fine

 

This ground is for the rear abs, the engine wasn't running right so I thought this could've been wrong but its not. I had a few vacuum lines disconnected and reattached everything, running a lot better now.