JoeZem

I'm visiting my parents who have a 2000 Ford 150 5.4L truck.

It needs to be jumped to start.

Anyway, My mom had a neighbor replace the battery. That wasn't it, he took the battery back and put the previous one back in.
My mom took it to a repair shop. They did replace the battery and some other part or parts, my Mom just can't tell me what was done. I even went to the repair shop and they didn't want, or have time, to cooperate by looking up the repair work order -- but they are a very busy, small shop. Oh, and this battery going dead again did not start until several months after they repaired it.

Ok, it's dead... completely dead, something is draining the battery. I can jump start it and it will run and charge the battery. A while later, I can start it on its own.. but a day or two later, it is completely dead again. Also, After I get it started, I can disconnect the battery and it will stay running all day long and everything works, so the alternator seems to be working fine.

Now, a new problem (or hopefully a clearer sign of the real problem)... yesterday, I had to jump start it to move it... I jump started it, I moved it, I let it run for a little while to charge the battery. I went back to it and shut it off, but it didn't shut off. Everything was working, except for not being able to steer it or put it in gear due to the steering wheel being locked without the key inserted.

The only vehicle I've had do this was an 80s F150.. and I tapped on that ignition relay that was on the passenger fender right next to the battery to get it to shut off. Well, that relay isn't there on this truck. It was dark and I was working with a flashlight... so I didn't see that relay anywhere...

So, I opened up the relay box under the hood and pulled one of the square relays (only two of the larger ones are used in the truck) and that shut everything off.
Turns out that was the PCM-Power Control Module relay and is #302.

I would guess that the battery draining and needing to pull the PCM relay to shut it off are due to the same defect?

Any help would be appreciated. I need to leave town on Sunday and I'd really like to get this taken care of before I leave because it will be at least six months before I'll be able to return.

Thanks for any help!

-Joe

JoeZem

I've been researching this since I posted the above information. Now, I'm learning about the problems with a Generic Electronic Module (GEM) on many older Ford trucks that may be the cause.
I've also learned that the power door locks to not work - they do not lock or unlock but the solenoid does click, they just don't shift.

It seems as they may have to take this to a shop because I wouldn't be sure how to test it and the GEM replacement seems to be more than I have time for on this visit.

01-7700

With truck off - Remove the neg battery cable and put a meter between the cable and the battery. A short somewhere in the truck will cause a voltage to be read on the meter. You can then remove each fuse, relay, etc. one at a time to hopefully isolate the problem to a certain circuit. That will narrow it down much. Also jiggling wires may change the voltage reading and give you a clue on the location of the short.

lutter5-0

You will be reading the current draw, not voltage.

white89gt

^^^ And this does not read out of the same port in the meter as the voltage. Not all meters will measure current draw (amperage) either.

white89gt

This is a "how-to" on what exactly you need to do. 01-7700 has the right idea, just not measuring voltage, and more to it.

https://www.popularmechanics.com/car...attery-drains/

01-7700

correct - that's what i meant