I have an electrical drain (I think) plaguing my 2003 G35 coupe 6spd.

About 4 months ago, car wouldn’t start, replaced the battery thinking it’s a battery being old issue. Didn’t think twice about it, and now its happened again.

I left the car for 2 days without turning it on, and the power door locks didn’t even work. I plugged in a battery tender with terminals still attached, the battery tender kept blinking saying it wasn’t charging. I took off the terminals put the tender directly on the battery, after a day of charging, the car started. I decided to leave the car with terminals connected to see how much power it drained. Car went from 12 volts (per multimeter) to .84 volts in a matter of 24 hours.

My guess is that there is some kind of huge draw, (I checked to make sure no lights were on.) that is causing my car to drain power when parked. I am going to guess this vs an alternator problem, mainly because of my testing with the terminals off the battery, then when I put the terminals back on, it killed the battery.

Thoughts? Common ways power drains? Places ground outs happen? I’d like to mention I have one of those plug in ipod adaptors that goes in the back of the deck (with the original harness) and hardwires the ipod to the disc changer function. Never had problems with this before, but I thought I’d mention.

 

Use an ammeter and measure current draw. Anything over 50mA needs to be investigated.

These headunits have a tendency to go bad and draw excessive current with the car off. Also, the auto headlight system can do it, as well as a bad alternator. The only way to know for sure where your issue is coming from is to measure the current draw.

 

The factory Bose amps also have been reported as an excessive current draw. Hooking up an ammeter while swapping out fuses can be a fairly quick way to determine what part is causing the current draw.

 

It's definately your radio/ac head unit. Same problem here. You can go the double-din route, or if you're cheap like me, pick up one of these. - batterybrain.com

 

Sounds like a good course of action.

so keep the multimeter on the one that monitors current or how many amps are coming out.

Then pull fuses and if the amperage goes down I have a winner (or loser in my case).

 

Pulled the blower fuse(2 of them 15a)

Pulled the radio and heater fuses also.

When I put the fuses back in, I had no radio controls, no ac controls, both showing 75 degrees auto on fan..


still not understanding where I need to hook in the ammeter to figure this thing out.

You cannot directly connect the am meter to the battery terminals, where do i hook it in?

 

You have to disconnect the ground terminal of the battery and hook the ammeter up in series with the battery and ground cable. You need to be careful not to turn anything on while you do this otherwise you may damage your ammeter or blow a fuse in it.

Not a good sign on theradio - I would make sure the fuse went back in the right spot and that the fuse wasn't damaged.

 

So, what if I use a jumper cable from neg bat terminal to am meter.

Other side of am meter to the ground terminal (neg)

 

Any chance you'd be reached by phone or online chat?

I'd like to discuss this more...

415-633-6318
stevenching2@gmail.com
aim: l240sxedl

 

As long as the ammeter is in between the ground cable and the battery it should work. They are polarity sensitive so make sure you connect the (-) of the ammeter to the ground wire and the (+) of the ammeter to the battery ground.

 

Done! the source of the problem, the 3 part fuse

10 amps on the multimeter in like 3 second intervals
BCM 50amp fuse
ETS 30 amp fuse
RAD FAN 40amp
(all connected together) big blue fuse


i can also hear a relay clicking on and off inside the car somewhere.

Fuse is legit, not blown.

 

Pages 4, 5 , 73 seem especially helpful... although I'm not sure how I'm susposed to test for all these components.

I see one of the things that all these go out to is "seat" wondering if that is power seat? I had my drivers side power seats stop working 6 months ago.

 

Sounds like you are well on your way but I wouldn't stop at the 3 part fuse. You'll need to narrow it down a bit more then that because I believe the 3 part fuse fuses a ton of branch circuits that all have their own smaller fuses. A 10A load will definitely drain a battery.

 

Not really understanding where everything goes to? And how to test for it?

 

Did you pull all the fuses one by one in the drivers kick panel?