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-   -   "Backup" circuit and drain (http://legacygt.com/forums/showthread.php?t=199613)

AndrewZ 01-13-2013 01:26 PM

"Backup" circuit and drain
 
Hey LGT,

Car is a 05 OB MT Ltd. I'm getting a 220mA drain with the car off when I have the Backup fuse (under the hood, 20A) in place. When I disconnect it the drain drops to 5mA.

I've searched the boards. People suggest that this has to do with backup lights - that's not the case. With the Backup fuse removed everything (3rd brake light, backup lights, door lock) related to the tailgate still works. When I thought it was related to the backup lights I checked the wires running to the tailgate and their insulation didn't show any wear

I've noticed that with the backup fuse pulled my key FOB and my interior lights don't work. The fuel pump, dash, and headlights still turn on when I put the key to ON in the ignition.

Does anyone know what all the components on this circuit are, and what might be causing the current draw/battery drain with the car off?

CraigLee 06-25-2015 10:48 PM

I have the same problem - did you find the solution?

Max Capacity 06-26-2015 10:46 AM

http://people.csail.mit.edu/ilh/vacation/

will the service manual help you in your search for an answer.

heiche 06-26-2015 02:48 PM

Quote:

Originally Posted by Max Capacity (Post 5179262)
http://people.csail.mit.edu/ilh/vacation/

will the service manual help you in your search for an answer.

Maybe something on page 5225 - 5228?

EDIT: could it be a small light that's staying on? like in the trunk, glovebox (if it has a light), etc?

5thElement 06-26-2015 03:10 PM

Check out the wiring harness in the wagon lid. Since this bends back and forth every time the rear is opened those wires get "stressed" a lot of cars these days have this issue. My neighbors Ford Sedan kept blowing Brake light fuses because of this issue with his trunk lid wiring. I wiggled the wire harness around a little and must have moved the wires enough to break the connection/short. He hasn't had a blown brake light fuse since then, and also hasn't opened his trunk since then. Before that every time he put the brakes on the fuse blew, therefore locking the transmission (brake interlock disabled) I suspect your reverse lights wire is shorting against the body somewhere around that bend area.

mindriddle 07-29-2017 09:10 AM

bringing this back from the dead. I have the same EXACT problem with a 220mA draw. I pulled the fuses im the engine bay along with the fan relays. Nothing. Pulled fuses by the pedals. Still no change. Pulling the back up fuse was the only thing that dropped it but my key fob stopped working (havent checked what else it disabled when off). Any suggestions?

SVXdc 07-29-2017 05:03 PM

The fuse in the engine bay labeled "backup" is for many things that need power even when the key is off. The label means "memory backup", not reverse gear lights.

See this post for a list of things on that fuse in a 5th-gen car. Your 4th-gen will be fairly similar.


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