feets

My 92 D250 has developed a taste for battery power. It has a draw that is sucking the battery flat overnight.

A few years ago I replaced all the fusible links with a large fuse block. The draw has been traced past the block and into the cab. 3 of the 6 fuses showed a draw.

Before replacing the fusible links I had a couple bad links that caused current backfeeding issues. Hit the window switch and the CEL, wait to start, brake warning, and water in fuel lights would come on. Turn on the A/C blower switch and the warning lights would trigger again.

All that went away when then links were replaced with fuses.

I've pulled each of the fuses from the block inside the cab and there is still a draw with all the fuses, relays, and flashers laying on the floor. I guess the only thing left at this point is to start unplugging every wire connection until I find the culprit.

Have any of you guys had this problem?

NJTman

Had a draw, and still do, that used to make my battery weak as well. Turned out the battery needed to be replaced, and the draw was my stereo system that was pulling the power. I'm sure you are correct that by pulling each individual wire, you'll find your culprit.

Our trucks are pretty simple, with no real computer to speak of, I cant imagine, unless you wired something wrong, or you have a bad switch that is keeping something on all the time, that it shouldn't be relatively easy to find.

Service lamp under the hood, glove box light, etc. Other than the radio, not much left to pull power without actually being actuated.

feets

There was a 5 amp draw on a fusible link circuit with all fuses removed and the alternator unplugged.

The draw went away when the ECU was unplugged.

My old Optima battery is 10 years old. It seems a bit resistant to hold a charge. I've got it on my intelligent charger now and will check it in the morning. If it doesn't look good then I will toss the Exide Edge AGM battery in the truck.

I guess the best case scenario is the ECU losing the voltage regulator circuit and needs the bypass done. That's a bit of a long shot since the alternator charges when the engine is running.
Worst case means chasing down another ECU.


I put everything away for tonight.

cougar

Disconnect the auto shut down relay or disconnect the field wires at the alternator. The field is the only thing I can think of that will draw that much power through the PCM.

feets

It looks like it was the A/C relay that was hanging up. When I unplugged it the draw went away. I played with it a bit and got repeatable results. Stuffing a new relay in there fixed the issue.

Now the truck is over charging. I was watching the battery voltage bounce between 16 and 17 volts.

I guess the voltage regulator bypass needs to be done.

feets

Again, it boils down to the basics.

I chased the grounds and cleaned up all the connections. The voltage fell back into line and the truck is happy again.

That 10 year old Optima may have seen its last. I left it on the smart charger all night and it is still taking 2.7 amps of a charge 16 hours later. It started with 11.something volts and is up around 12.5 now. The charger is set for an AGM battery at 2 amps so that side of things is correct.

I did notice that the Exide AGM battery has the engine rolling quickly and firing before one full revolution.