Jpilk99

Hi all,

I found a significant draw, (~ 200ma), on my '08 TL and located it within the "interior light" circuit. I can't "see" anything obvious, like a light remaining on - and am looking at the circuit schematics for all the possible culprits. How would a ...smart person go about this? Go to each point in the circuit and test to make sure it's operating correctly? Turning on and off when it should? I did find one of the dome lights was not coming on and assumed the bulb was bad - so ordered new one. Not sure if I can test an LED for continuity the same way I would a conventional filament bulb... Could always pull the Passenger side bulb and plug it in...

Thanks,

Jay

cnp

Hi Jay,
A few questions/thoughts:
1) Does the mA draw fluctuate in any way?
2) Did you wait minutes to even an hour after car was turned off to see if mA draw drops (some devices take a bit to go into 'sleep' mode)?
3) I think the fuse for the lighting circuit is a blade fuse, correct?
4) Does this circuit have any relays or electronic modules (eg keyless receiver unit, power mirror control unit)? I would always look to relays/modules first before considering a bulb. Devices downstream of a bad relay can still work.
5) Did the whole problem get identified from a dead battery? Have you checked the integrity of the battery? It's in good shape? Lead acid batteries will likely be ruined by drains below 12.0 volts (roughly 50% capacity).
I don't have access to my service manual at the moment, but if you have the circuit image handy it would be nice to have you post.
Thanks
Carl

twokexlv6coupe

"Interior lights" is which fuse # of which fuse box? #6 fuse on the under-dash fuse box?
B/c that's also; HFL, ignition key light, keyless receiver, power seats & mirrors control & roof console.
How I did my parasitic draw test was leave the DMM hooked up in series of the negative battery terminal & cable, and individually unplug each and every circuit on that fuse, and watch the DMM to see if it has a DRASTIC drop. If it does, you've found your problem.

My money is on your HFL has never been unplugged. An EXTREMELY common battery draining cause on these cars.


^^ THIS is very important!!

cnp

I had the ubiquitous HFL drain in my son's TL and disconnected. But I recall that circuit was not interior lighting circuit but maybe fuse 7 ??? It's been awhile. To the OP -did you make sure the trunk light is not on when closed? Some people forget that one.

Rottle

That's odd, because I recently unplugged both 6, and out of those you mentioned, seats actually work

twokexlv6coupe

I may have been looking at the wrong FSM. There's 2 diff ones for 04-06 & 07/08. Of which I'm almost positive the circuits did get moved around to different fuse #'s.

Regardless, use my methodology to your correct FSM year.