Having a problem with my 1989 F 150. Since I have had 3 years now I've had to replace the battery twice now and the altenator. Seems excessive on the battery replacement. Welcome any suggestions on where to start troubleshooting the problem. Worried I may have a wiring or grounding problem.



David Gibson
Davidsatcom@bellsouth.net

 

It is most likely one of two things. The first is a tired alternator. If your alternator isn't up to par it will only minimally charge the battery so that it never reaches its full potential. This will cause the battery performance and capacity to suffer and your battery will become worthless before its time. There are two simple ways to check your alternator. Drive around for a while then go to an auto parts store that will do a free battery and/or alternator check. The easiest way, though, is to use a multimeter (voltmeter). Turn on your truck and then measure the battery terminal voltage (red lead to the positive terminal and black to the negative terminal). Standard voltage for an open circuit battery is 12VDC. The alternator puts out about 14.4VDC so that the battery will become a load (and get charged). If your voltmeter isn't reading over 13VDC, I'd say your alternator needs to be retired.

The second possibility is much more frustrating and time consuming. A weak or intermittent ground. This can be caused by loose connectors, old wires or poorly installed aftermarket components. Stereos and off-road lights are prime examples of battery killers if not installed well. If you have anything like that I'd start there first. Otherwise, somewhere in your truck is a circuit that is conducting (on) when it shouldn't be. Look around hinges for cracked or frayed wires, check under the dash to make sure none of your pedals have rubbed the insulation off of wires and check that all of your underhood firewall connections are tight to start with. Other than that, you can pay a shop to hunt down the ground or just disconnect the battery every time your going to park it for a while.

Good luck and happy hunting!

 

Have replaced the altenator and battery recently but believe there is another problem that has caused those to go bad. Found a ground wire just hanging Cleaned the area and replaced it and so far no problems. Keeping my fingers crossed.

Thanks for the help.

 

Well again one day where the truck wasn't run in over 24 hrs and it got a little cold that night the truck would not start again. Have had battery and Altnator checked, they are both good. Someway, somehow the truck has a slow drain. So far unable to track it down. Any further suggestions anyone has are welcome.

 

Check the fuel pump relay. I know it sounds bizarre, but I had one stick on a '86 Ranger, my fuel pump ran all the time and kept running my battery down