LJ78 Battery Drain

[tiresandals]

New battery.

But its dead if I let the cruiser sit for more than a couple days. I put a volt meter between the battery negative terminal and the frame. It looks like there is a draw of about 3.5A. That is quite a bit. I pulled every single one of the fuses (in the fuse box next to the driver's foot). Power drain didn't change. Maybe I should go through the fuses again. Are there other fuses aside from those?

I don't know if it's related, but regardless of weather I've got the key in the ignition, when the driver's door is open there is a dinging bell alarm sound. It like as if I left the key in the ignition in most other cars. Is this normal?

Looks like the drain is coming from the white wire. Any idea what that one does?

 

[jblueridge]

That is too much of a power draw. It should be more like 0.35 amps for the clock and stuff that is always on. I have different wiring diagrams, but that white wire might go to your alternator… the main charging wire. Also it seems to go to the main ignition relay. Maybe that is why you get the door open pinging. I’d take out relays and fuses. Some equipment is not wired through the fuse box. The short wires right off the battery with fiberglass sleeves in your photo are fusible links that act as fuses too.

 

[AirheadNut]

Wiring diagrams for your LJ78 are posted in the online manuals sticky thread at the top of the 70-series forum page, you should be able to trace where things go with them.

 

[jblueridge]

The white wire to the alternator runs right to the battery. Disconnect battery if you want to get that wire loose.

 

[tiresandals]

I looks like the white wire goes to the ignition switch, alternator, and ECD 15A fuse. I've disconnected all 3 and I'm still getting the 3A drain. Is there something I'm missing?

 

[ceylonfj40nut]

Just encountered this on a friends rig. Was puzzled. Turned out his ignition cylinder was not turning to the off position completely. Cylinder was worn. He could use any key to fire it up. Check into this.

 

[tiresandals]

Just encountered this on a friends rig. Was puzzled. Turned out his ignition cylinder was not turning to the off position completely. Cylinder was worn. He could use any key to fire it up. Check into this.

I found this on mine as well. There is a button on top of the ignition switch to lock the key in. Its so worn that the key will come out in any position. However, I unplugged the ignition and I'm still getting the drain.

I've learned that most of the problems with my cruiser have multiple causes. That what happens to a vehicle after almost 30 years... But I'm getting them fixed one-by-one. Thanks!

 

[tiresandals]

I made some progress. I removed EVERY fuse, ignition, and the alternator. This eliminated the drain. Then I started replacing stuff. The ignition wasn't a problem.

ANY ONE of the following connections will cause the drain:
- DOME fuse
- RADIO fuse
- ECU-B fuse
- Alternator

 

[tiresandals]

Glad I figured it out with the help of the tech from XXXX Service. When I called about the repair made to the alternator, they asked me to bring it by anytime and they would check it out. Said leave it on the truck bring the truck by and we'll see it in operation. We won't charge any more for issues related to the alternator. Tech asked did you check the battery ground terminal for corrosion etc? hmmm I did look at it and the negative looked good to me. Feeling stupid for not knowing the corrosion on the terminals could be a cause for SPIKING VOLTAGE- corrosion usually caused me to have low or no charge to the battery and not starting problems - Instead of taking the truck in I decided to check the terminals, I asked my Dad to come over and clean the terminals for me while I was at work. He did so and said the POSITIVE terminal was really corroded underneath the clamp. Since the cleaning of the terminals, I've driven it 2 days with NO issues regarding the voltage spiking. A few more days and I'll be sure that my Dad's handy work did the trick. Turns out the techs clue may have been the solution. IF the problem STAYS gone -I'll call him in a few days and report that the battery posts were cleaned and that fixed it and thank him for that tip. ( and ask if I really needed a voltage regulator replaced or did they assume that it was bad) Out $80 for not knowing battery post corrosion would have the unexpected (by me anyway) affect of causing voltage to spike and embarrassed to not KNOW that would be a possibility. Never imagined I'd stump the panel. Lessons learned- battery posts corrosion causes more than one adverse affect and patience is rewarded. Hope someone else gains from this experience! Will reply to my own post again if the issue returns.

F150 Forum

This seems likely since there are multiple systems that are effected. So, I'm going to clean the terminal clamps and grounding wire etc.

 

[Gun Runner 5]

Not saying it’s your issue but I once had a short in a dome light that would drain the battery in a few days.