Hey everyone.. Ive got another question about my 1990 4.9l F150.. I was out looking under my hood this morning and saw that the negative battery cable was basically falling apart. A lot of the rubber covering was cracked and peeling off, and the cable underneath was extremely corroded.
This afternoon I got a new cable at walmart. When I was taking off the old cable the bolt that is halfway between each end (the bolt that grounds the cable to the frame) was so rusted that i couldnt remove it. so i cut off the cable at each end of this bolt/clamp thing and just put the new one on.
I'm wondering if I really need to have the cable there or not, because if I dont need to, I dont really wanna have to frig around with it. You guy's help is greatly appreciated!

-Dave

 

You need a cable that goes to the frame and block for proper grounding. It doesn't have to go to the exact same spot, but you still need a frame ground. Napa has the cable for 18bucks.

Adrianspeeder

 

Thanks adrianspeeder!
Tomorrow I'll find a way to ground that cable to the frame.
Now this is probably a really stupid question, but i dont know to much about electical stuff, why do you need to have the cable grounded to the frame?
What happens if the frame isnt grounded? I was just curious about that..

-Dave

 

Everything metal on the truck acts like the ground wire for every device. Most devices are grounded to the frame, so lacking the return path from the frame to the battery can cause strange electrical problems.

Adrianspeeder

 

There should also be a pigtail on the cable that ends up going to the fender and/or radiator support. As mentioned, everything electrical has to have a path back to the battery (ground). Running a ground cable straight to the engine is great for everything that's grounded to the engine, but other things, like your radio, lights, etc., are usually grounded either to the body or the frame. Since the motor mounts have rubber in them, the ground connection between the engine and frame is weak, at best, so they have the cable also grounded to frame via that bolt you mentioned. Likewise, since the body is separated from the frame with rubber bushings, the ground connection there isn't great, either. There are several places throughout your truck where a ground strap connects two areas to help with the ground connection, but nothing beats a direct line from the battery.

FWIW, another option for you would be to buy a second cable with end fittings for a bolt on both ends, and run it separately from the engine to another spot on the frame. That way you wouldn't have to screw with the cable you've already installed.