Just as the title reads, I'm pretty sure I've got a parasitic drain somewhere in my dome light circuit in my '92 3FE.
First a little background:
I swapped the original 3FE for another 3FE out of a '92 this summer when I broke the crank in my original motor. The swap went fairly well considering it was my first. I did have a short when I put the new motor in that was due to the two wires being pulled from the #6 injector plug and shorting out. It was blowing fusible links. I repaired the wires and the truck ran well. Just weeks after getting the '92 up and running, the headgasket in my '94 blew. I depended on the '92 the entire time the '94 was down, and it only gave me one major problem. I snapped the fan belt and the motor got a little too close to the red on the temp gauge. I caught it early, towed it back to the house, and replaced the belt. Everything seemed to be back to normal again. Before the belt issue, it seemed like the headlights weren't as bright as they should be, but I attributed that to the age of the lenses. The lights did seem to get brighter with higher RPM's, so I was thinking my alternator brushes were on their last leg. I had plans to put the '94 away for the winter to protect it from the salt, so following the headgasket job, I put about 600 miles on it to ensure that everything was good to go before storage. The '92 had been driven about once a week during that time, without issue.
Now for the mystery:
The '92 was driven to the airport, sat for about 5 full days, and drove back home (10-15 miles on the highway) without issue. It got back on a Sunday, and wasn't touched until Saturday. On that Saturday (one week ago) I tried to roll down the rear windows with the truck off to re-install the door panels. The battery was dead. The battery was replaced this summer. I immediately thought alternator. I pulled the alternator and brought it in for testing. It was good to go. I put it back in the truck, jumped it, and brought it back to the parts store for a in-vehicle test. Again, it tested good. That eliminated the alternator or the cables from the alternator to the battery. Then I thought parasitic drain. I got out the multimeter to find .085 Amps being drawn from the battery with the truck off and no accessories running. I went through the process of pulling individual fuses and retesting the current draw in an effort do find the drain. I found the dome light circuit to be the culprit, because with the dome fuse out, the current draw dropped to .005 Amps (all tested with a charged battery).
I tried to find the issue with the circuit by pulling and testing all of the dome/map light switches and bulbs. They all checked good in the truck. I also disabled all of the door switches, the rear hatch switch, and the glove box switch but the current draw remained the same .085 Amps with the dome fuse installed. I took a look at the wiring diagram in the FSM, but that doesn't show much else on the dome fuse. For now, I've pulled the dome fuse and plan to let the truck sit for a week to see if the battery is drained at all. I'd like to get this figured out because its a bit annoying to be without dome lights. I'd also like to make sure that this problem isn't being caused by something more serious, or possibly causing something more serious.
I've done about all I can think to do with my minimal electrical experience and a multimeter. I'm at a loss at this point, but hoping someone else has some advice. I did test my '94 for the sake of a "control", and that tested to be at .025 amps with accessories off. That battery does not drain on its own and I haven't ever had starting issues on that truck. I've seen on Mud that people ignore drains .1 amps and lower, but that is the only thing I can seem to find that could be killing the battery.
Thanks in advance
-TT
First a little background:
I swapped the original 3FE for another 3FE out of a '92 this summer when I broke the crank in my original motor. The swap went fairly well considering it was my first. I did have a short when I put the new motor in that was due to the two wires being pulled from the #6 injector plug and shorting out. It was blowing fusible links. I repaired the wires and the truck ran well. Just weeks after getting the '92 up and running, the headgasket in my '94 blew. I depended on the '92 the entire time the '94 was down, and it only gave me one major problem. I snapped the fan belt and the motor got a little too close to the red on the temp gauge. I caught it early, towed it back to the house, and replaced the belt. Everything seemed to be back to normal again. Before the belt issue, it seemed like the headlights weren't as bright as they should be, but I attributed that to the age of the lenses. The lights did seem to get brighter with higher RPM's, so I was thinking my alternator brushes were on their last leg. I had plans to put the '94 away for the winter to protect it from the salt, so following the headgasket job, I put about 600 miles on it to ensure that everything was good to go before storage. The '92 had been driven about once a week during that time, without issue.
Now for the mystery:
The '92 was driven to the airport, sat for about 5 full days, and drove back home (10-15 miles on the highway) without issue. It got back on a Sunday, and wasn't touched until Saturday. On that Saturday (one week ago) I tried to roll down the rear windows with the truck off to re-install the door panels. The battery was dead. The battery was replaced this summer. I immediately thought alternator. I pulled the alternator and brought it in for testing. It was good to go. I put it back in the truck, jumped it, and brought it back to the parts store for a in-vehicle test. Again, it tested good. That eliminated the alternator or the cables from the alternator to the battery. Then I thought parasitic drain. I got out the multimeter to find .085 Amps being drawn from the battery with the truck off and no accessories running. I went through the process of pulling individual fuses and retesting the current draw in an effort do find the drain. I found the dome light circuit to be the culprit, because with the dome fuse out, the current draw dropped to .005 Amps (all tested with a charged battery).
I tried to find the issue with the circuit by pulling and testing all of the dome/map light switches and bulbs. They all checked good in the truck. I also disabled all of the door switches, the rear hatch switch, and the glove box switch but the current draw remained the same .085 Amps with the dome fuse installed. I took a look at the wiring diagram in the FSM, but that doesn't show much else on the dome fuse. For now, I've pulled the dome fuse and plan to let the truck sit for a week to see if the battery is drained at all. I'd like to get this figured out because its a bit annoying to be without dome lights. I'd also like to make sure that this problem isn't being caused by something more serious, or possibly causing something more serious.
I've done about all I can think to do with my minimal electrical experience and a multimeter. I'm at a loss at this point, but hoping someone else has some advice. I did test my '94 for the sake of a "control", and that tested to be at .025 amps with accessories off. That battery does not drain on its own and I haven't ever had starting issues on that truck. I've seen on Mud that people ignore drains .1 amps and lower, but that is the only thing I can seem to find that could be killing the battery.
Thanks in advance
-TT
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I'd hate to see what you think major experience is...
popcorn:my kid likes these guys
)
