Battery draw down...needing electrical wizardry (1 Viewer)

[jfnall]

Here is the scenario. Battery is brand new. Alternator is putting out correct voltage. When the truck sits with key off, there is a full 12v draw. I can't find the source. I have it narrowed to the dome light fuse. All my door electrical door sensor pins are working correctly. The dome lights go on and off appropriately. The glove box light is working correctly, not grounded with box door closed.

Looking at the wiring schematic, it looks like the seat belt and carb cooling fan are tied to the dome light power, for what ever reason. My carb cooling fan seems to work correctly. Only switching on when hot, and shutting off when cooled back down.

So that leaves the seat belt switch or indicator. Is there a wire under the carpet tied directly to the belt where it clips in, and somehow hidden? This hasn't been a problem for 5 years, but changing the heater core seems to have made things weird. Should have changed the blinker fluid I guess.

And could the rear hatch light switch draw 12 volts, even if the light is off. Maybe the switch lever not in the exact spot to turn on the light, but still pulling power? Where is the rear hatch upper door closed sensor?? I figure if the door closed and the light goes out, the all that system is functioning properly.

Any ideas where to start testing? I have to pull the dome fuse to correct the issue. No fuse means no battery draw down.

It sucks to have a new $225 battery and the truck leave you stranded in 20 degrees at 2 AM!

Recently I changed the heater core, but I have already taken the radio out of the loop to know it isn't part of the problem. Same with all cig light plugs. Absolutely no items having power, and still a battery draw down, 12+volts

Ideas??

 

[NocalFJ60]

You got a meter that measures current? Disconnect a lead on the battery and put you meter in the circuit. Make sure it is current mode and you have some spare fuses and start with the highest current setting and then move down until it displays the current. Now pull fuses one at a time until current drops to zero. This will narrow it down first.

 

[popeyehj60]

he knows which circuit is pulling the current.

id pull the dome globe. break that circuit and see if it still pulling current. if its still pulling current, pull the hatch globe.
you've basically got to isolate every part of that circuit.

 

[rcmccars]

do you have an aftermarket radio? if so it may be the problem if it was wired into that circut, like mine was when i got the truck. it caused all kinds of problems.

 

[snowboardonsnow]

If you just change the heater core i would say start there... (around there) possible pinched wire shorting to a really poor ground so its not enough to blow the fuse. 99% of the time if something is recently changed and there is problems that change has to do with the source.

 

[snowboardonsnow]

also x2 on the radio people will pull those off whatever circuit is most convenient. And radios can go bad in a way to draw constant power but still work.

 

[snowboardonsnow]

" Should have changed the blinker fluid I guess. " LOL

I only clean the spark plugs in my BJ60 anymore otherwise something ends screwed up!

 

[jfnall]

I have isolated the radio totally out of the circuit. No power to it at all. Still had a problem. I will redo my ground connections and start my checking the bulbs and their switches,.

 

[cruisertom]

I would remove the seat belt indicator out of the circuit as well. Along with anything else. Are you sure the light goes out in the glovebox? Could be that since it is near the heater core. Also do you have a seat belt buzzer? I have had horn relays draw a battery down with the horn disconnected. Is there any relays on that circuit? Please let us know what you find.

 

[snowboardonsnow]

Good idea on the relays.

 

[jfnall]

The glove box light is tied to the dash lights. And the bulb is out of the socket. The light can only work if the head lights are on.

I have no seat belt buzzer. Never had had one as long as I have owned it. I tested the dome lights again and unhooked the switches all together. Neither one made a change in the voltage. Also unhooked the carb cooling fan and it made no change. I ran out of time, but I didn't get to the seatbelt wire to test it. Gotta take the seat out to access it.

Does the from dome light route up the driverside B pillar? Though I might need to check the wires routing.

If I had a positive wire messed up, it would cause arcing and potentially a fire. Don't have anything like that's going on.

I did change a headlight relay this summer. I will check those next and see. At this point I just leave the dome fuse out.

What is the fuse marked door? Is that for power door locks if these trucks had them??

 

[CardinalFJ60]

did you used to hear a click?

I'm chasing a minor, yet similar issue. I think I remember for a while when starting the cruiser, the volts would read low on startup then I'd hear a distinct "click" near the pass. footwell/side of vehicle and the volts would jump up to "normal". I don't hear that click and have a slightly low voltage reading - not relying on just dash gauge.

that's another way of saying I like the relay idea.

 

[jfnall]

The meter I am using it hooked directly to the battery and truck wiring. A mechanic showed me how to hook it up to show how much draw is being taken. Then from there I test different switches or circuits to see if the voltage differs with that change in a specific circuit.

The relay test is a good idea.

Where is the seatbelt buzzer and relay supposed to be located. I don't have one

 

[jfnall]

The meter I am using it hooked directly to the battery and truck wiring. A mechanic showed me how to hook it up to show how much draw is being taken. Then from there I test different switches or circuits to see if the voltage differs with that change in a specific circuit.

The relay test is a good idea.

Where is the seatbelt buzzer and relay supposed to be located. I don't have one

 

[jfnall]

After 12 hours of testing and taking apart, chasing wires, etc, I think I found the problem. The seat belt warning module is also the key beeper. I disconnected the Red w/ white stripe wire on that module and the problem disappears. Must have fried the whole module. Does anyone know if anything else is effected by this wire being taken out of the loop? If so, I might need to replace the whole module.

Second problem was the radio. Must have an internal short. I ended up running a separate fuse just for the radio and powering it off the secondary battery, not tied to the truck main battery at all. So if the secondary battery is drawn down, at least the truck will still start. Down side is, if I need to run my fridge for quite awhile without the truck running, I will need to remember to take out the radio fuse. This will cause the memory to be lost on the radio, having to reset the clock each time.

Lesson learned... Anytime you mess with the truck, always disconnect the battery.

Here is a picture of the seatbelt warning box. It is behind the panel on the passenger side right foot.

 

[lovetoski]

Glad you found the problem. I had a draw-down issue this summer...turned out to be a horn relay...took over a month to track it down. Was lucky it was summer...

Also glad to hear where the key beeper resides...I want to get rid of it.