Parasitic Battery Drain.....

[rothsean]

So I came home from a 10 day trip and my new battery was dead. I just replaced it because another battery died on me. I thought it was a bad battery, but now I see that I have parasitic drain.

I used a test light to check the system and the test light is on very strong with all items off and doors closed. When I pull fuse #12 the light goes out.


There are no other lights on in the system normally when the doors are closed. What could be in the #12 circuit that is draining?

Also, whenever I hook up the electrical wires to the switch for the engine compartment light it blows the fuse.

[Ozzie]

Fuse 12 feeds (aka: suspects):

1. Diagnostic Plug
2. Engine Compartment Light
3. Internal Dome light, Front
4. Internal Dome light, Rear
5. Glove Box Light
6. Door bulbs
7. Dimmer relay

One of those is probably draining your system - especially if putting the engine light on the circuit blows the fuse.
Try the easy ones first, like each bulb (2, 3, 4, 5, 6) and especially the connections to its socket.
Check one at a time, and see if your test light dims with each one.

I went through this before (turned out to be a radio went bad), since then I like to know my standby current, the current of a parked car. It's currently around less then 20ma which is being drawn mostly by the radio settings and the keyless entry, and the car can easily start after a week of sitting. It's easy to test your standby current, I cover it in the LED blog below.

[Ron]

8. Luggage Lamp.

[lindbergh]

You have a short in the engine compartment light wires, socket or switch. I would start at the switch, more likely culprit.

Check each light individually by manually closing the switch and watching that the light goes off for that switch. If all that checks out, move on to the dimmer relay.

[rothsean]

You have a short in the engine compartment light wires, socket or switch. I would start at the switch, more likely culprit.

Check each light individually by manually closing the switch and watching that the light goes off for that switch. If all that checks out, move on to the dimmer relay.

I have the wires to the engine compartment switch unplugged. I never plug them in since they blow the fuse when I connect them to the switch, along with a small spark.

[DMC5180]

The engine light switch can not internally short itself. It just opens and closes a circuit to ground. It needs load (Light bulb) load to not be a dead short. Check the Engine compartment light fixture for a possible short across the contacts where the bulb goes. (remove 2 lens screws) If nothing looks out of place, remove the bulb and reconnect the switch wires too see if the fuse pops again.


As for a drain on the fuse 12 circuit, make sure the door switches are turning off the door lights when the door is closed. Usually you can see through a gap in the door outer seal to see if the lights are on or off.

[rothsean]

I found it, it was the glove box light staying on.


Thanks for the input!

[DMC5180]

I found it, it was the glove box light staying on.


Thanks for the input!

Great, but what about the shorting issue with the engine bay switch/light assembly?

[rothsean]

Great, but what about the shorting issue with the engine bay switch/light assembly?



Not sure, I disconnect it for now. It is not the switch because I connected the two wires together with a wire and it blew the fuse right away. I will have to troubleshoot that one day.

[David T]

Not sure, I disconnect it for now. It is not the switch because I connected the two wires together with a wire and it blew the fuse right away. I will have to troubleshoot that one day.

It is common for that plastic housing for the light to melt and the brass parts touch each other shorting out that circuit. Most just leave a wire off the switch and never use that light anyway.
David Teitelbaum

[Ozzie]

It is common for that plastic housing for the light to melt and the brass parts touch each other shorting out that circuit. Most just leave a wire off the switch and never use that light anyway.
David Teitelbaum

Agreed, get a new housing, put an LED on it, and you're good to go.
( Blog: "LEDs are cool." (http://delorean2109.blogspot.com/2008/11/leds-are-cool.html) )

I also put a small toggle switch on the housing, at the bottom of it, in case I want to leave the cover up w/o the light on (yes I could just unplug and plug back the switch, but this seemed a more stealthy and convenient way to do it.)