I just got the truck a couple of months ago. I noticed today that I had a black battery cable that was behind passenger battery and ran in front of the radiator and back behind the drivers headlight. Both ends are un-hooked. Drivers side battery the neg. goes the the firewall and the pos goes to another starting cylinoid. Should the neg of both batteries be connected?

 

The passenger side battery tray is the MAIN battery.

Doesn't make sense why the main battery's negative cable is unhooked.

Is the truck running off the auxiliary battery alone? Or is it the only battery installed?

What truck is this?

 

78 F350 I messed up. The main battery neg is hooked up. But there is another cable that runs from one batter to the other that Isn't and was wondering if it is supposed to be. Can I hook it up and remove the neg wire going to the fire wall?

 

Both batteries are supposed to be hooked up on both terminals. Perhaps a PO took it off because it was causing issues?

The dual battery setup is a simple one.

 

The battery on the drivers side is the auxillary battery... for campers or trailers...and the solenoid on the drivers inner fender is not a starting solenoid, its an isolating solenoid so when the engine is shut off, your camper (or trailer) will pull power from just the auxillary battery, not the main starting battery. When the engine is running, this solenoid allows both batteries to be charged. Sounds as though the P.O. had a problem with the aux. battery charging and just hooked the main battery and the aux battery together with a wire to get them both to charge. I'd check that aux battery solenoid on the inner fender to see if its working properly.

 

Illustration: Section 145 / Page 10.

 

Mine was unhooked also, no battery, I am guessing that some folks when the batt dies, don't want to spend the money for a new one..

 

 

Thanks for the responses. Where do I find section 145 / page 10 ? Thanks Chad. It's hard to tell where the neg cable is going too.

Dallas

 

I just showed it to you in my previous post. Did you not see the pic?

It is from the 1973/79 Light Truck parts catalog.

 

Is the neg going to 14301? Where is that going too?

 

14301 is the negative battery cable.

It's usually grounded somewhere on the engine block.

(14300 is the positive battery cable)

 

Negative. One positive cable goes to a relay on driver's side fender. The other goes to a grounding point.

If you have all the parts listed in the illustration, inspect for any foul play.

A wiring diagram would be better.

 

My neg on that battery goes to the fire wall. That is the only thing hooked to the neg.

 

Then this is incorrect.

According to my 1979 wiring diagram, it should be grounded directly from the post to the engine (the usual grounding point).

The positive cable should go from the post to the accessory safety relay specific to the auxiliary battery.