I have an '84 F150 with the in line six and the truck runs great but it has a dead short in it somewhere. I can charge the battery while both battery cables are unhooked and the battery charges just fine. When i go to hook up the battery cables I get a little spark from the positive side. While parked in my yard with the battery hooked up the charge will only last about an hour or so. I have replaced the altenator and the voltage regulator. Does anyone have any ideas on what the problem might be before i go spend a fortune at the shop having it fixed?

 

Sorry problems like this can be a pain in the rear. Something is most likely draining your power away and I would suggest looking over your wiring under the hood. you could have a wire that touches the frame or other conductive area that appears just fine but if you lift it up or turn it to the side you would see the insulation worn away where it touches metal and is siphoning away your power.

You could also check if you have recently installed something like a in dash deck to double check the wiring or anything else you can think of.

There could be other possible problems hopefully other suggestions get posted!!

Hope this helps.

 

"While parked in my yard with the battery hooked up the charge will only last about an hour or so."

That is quite a drain, I would think that some wires are getting somewhat hot to the touch. Feel around, you just might find some hot wires. If so then start removing fuses to locate the right circuit to troubleshoot.

What I have done in the past is to hook up an ammeter between one of the battery cables and the battery. Do not try to start the vehicle while the meter is hooked up, you will fry it. Keep the keys in your pocket with the ignition off. You can use a multimeter set to amps if you have one. However, the meters I have only go up to 10 amps on the current scale and could very easily be over ranged if there is a draw like you describe.

If the ammeter does not show any drain then I would hook up my multimeter on the high current setting. A few mA of draw is normal, things like clocks and such will always draw something.

Now start pulling fuses until the draw stops, you now know what circuit to troubleshoot.

Sorry for the rambling, hope this helps

 

Tote-M-Pole is giving you good advice, except you need to keep your battery disconnected and use a voltmeter set to the resistance scale. That way you don't have to worry about high currents and frying your meter. Put the meter between the posative and negative wires and see what the reading is. Have EVERYTHING turned off, with the doors shut. The higher reading the better. 12 ohms will draw 1A and you should definitely have more resistance than that. Pull fuses, move the wiring harness etc until you see the number change.

 

Odd are if you have a trailer hitch the short is in the light circuit for the trailer. If you have installed a remote start it may be in the ground for your brake lights. Pull fuses for your lights, acessories and re check for a ground/short. There is a ground short tester to zero in on the area. I take it the radio functions right so it isn't blown up. Some trucks rust alot behind the cab along the bottom of the bed, a piece of metal may have damaged the wiring. Look along the rails under the truck if you locate the rust. If you don't blow a fuse its a slow boat to china type of wire rub problem probably. Heater motor and controls can use up a lot of power so shut it off/on to test it/disconnect it. Same for AC pump clutch actuator. Does it make a lot of noise.

 

Polar,

I do not know why I never checked it like you described. I will next time I run into an issue like this again. It is a good way to use Ohms law. I=V/R.