Electrical Problems (sigh) [Archive] - GrandAmGT.com Forum

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alocaurd
11-16-2009, 09:40 PM
well as the title states, i have electrical problems.

not sure how long ago it started, but my battery started dying, sometimes within 4 hours, sometimes not for 48 hours. i got a multimeter and connected to determine my problem.

with the car off, i was drawing 3 amps! through the process of elimination, i've narrowed it down to the center connector of my BCM. when i disconnect this connector, my current draw drops to 0.50~ amps.

now, i have done the independent fogs mod, the disable DRLS mod, and the disable auto lamps mod as i have HIDs. only the DRLS and Auto lamps pertain to the center connection. i have disconnected the ground for the auto lamps and plugged back in, with no change. i have disconnected the two wires for the DRLs and plugged it back in, still with no change. the other ends of all the wires and shrink wrapped and sealed. the only thing i havent tried, is actually reconnecting all the wires, which would be very tedious, and under the circumstances, doesnt seem like it would help.

my thoughts are either a problem with the BCM itself, or, my other question, is it may be a stripped wire or two in my main wiring harness in the grommet where it goes through the firewall, as i pushed a hole through it with a sharp object for my vacuum hose. does this connect to the BCM? would touching wires cause this without blowing the fuse?

Thanks for any input! for now i keep my battery disconnected when parked overnight =/

AaronGTR
11-16-2009, 10:14 PM
Did you check to see if any of the relays in the underhood fuse box are staying on? That might help pin point which circuit is drawing power. I had to do that once with mine.

Malaclypse
11-16-2009, 11:17 PM
Unfortunately .5 A is still too much. You want to be down to below 25 mA for your battery to really last.

That's .025 A

Start pulling fuses until the draw goes completely away. And yes I've seen current draw issues from BCMs before but can't make any guarantees without seeing the car.

alocaurd
11-16-2009, 11:46 PM
yes i do realized that .5 amps is too much, but it is the bulk of the problem. i stopped pulling fuses after that fuse, although now that you mention it, it could be a combined problem. and te aaron, i started my elimination at the fuse box under the hood and found it to be the fuse in slot 3, which is climate control, left signal and brake lights, and body control. i eliminated the lights and found the same current drop from unplugging that connector of the bcm as just pulling the whole fuse. you still may be right though as mentioned above that .5 amps is still too much. ill pull the rest of my fuses tomorrow with the bcm fuse connected to see if i can get the same drop in current from another fuse (maybe the circuits are shorting together?) or a different drop.

edit: 1)excuse any spelling or punctuation this is all done from my phone

2) i've heard anything below 50mA is fine, which is 0.05 correct?

ltpats
11-17-2009, 05:04 AM
yes i do realized that .5 amps is too much, but it is the bulk of the problem. i stopped pulling fuses after that fuse, although now that you mention it, it could be a combined problem. and te aaron, i started my elimination at the fuse box under the hood and found it to be the fuse in slot 3, which is climate control, left signal and brake lights, and body control. i eliminated the lights and found the same current drop from unplugging that connector of the bcm as just pulling the whole fuse. you still may be right though as mentioned above that .5 amps is still too much. ill pull the rest of my fuses tomorrow with the bcm fuse connected to see if i can get the same drop in current from another fuse (maybe the circuits are shorting together?) or a different drop.

edit: 1)excuse any spelling or punctuation this is all done from my phone

2) i've heard anything below 50mA is fine, which is 0.05 correct?

What is the BCM supposed to draw to maintain its memory?

alocaurd
11-17-2009, 12:10 PM
What is the BCM supposed to draw to maintain its memory?

i'm not sure, but that also brings up another point, which is that i have 3 colored gauges that draw current to maintain color memory. i doubt this will have any huge bearing on my current draw though.

Malaclypse
11-17-2009, 06:14 PM
What is the BCM supposed to draw to maintain its memory?

A draw I would consider average would be about 15 - 20 mA. This includes memory retention voltage to the PCM, BCM, RCDLR and Radio. Onstar will draw alot more current but that's a whole other beast.

To the OP: Leave the BCM fuse out and continue pulling fuses underhood. That'll allow you to narrow down the other components drawing current more easily.

The electrical system is kind of like a tree. The battery is the trunk. The underhood fuse block is the first split of branches.. the interior fuse block is where those branches from the underhood block split again.

So pulling each fuse under-hood will narrow down to three or four fuses inside the car.

alocaurd
11-17-2009, 08:44 PM
well i write this message from a laptop beside my car. i've discovered that my capacitor/amp cause a funny situation. unplugging my amp has the same affect as pulling the fuse mentioned earlier, bring draw down to around 0.5. this being said, obviously going to be checking that out. furthermore, i now see that pulling the previously mentioned fuse, plus the related one for the RH side, plus the amp, lowers my draw to a steady 0.05~0.06. This would seem suitable with those fuses plugged in, but seeing how the BCM is getting no current for memory, this still seems high. im going to continue pulling the rest of the fuses, but so far all the other ones pulled have had no effect. input?

Edit: just figured out that a little volt meter built in to my battery post was messing with things. still something peculiar going on though. swithed my multimeter to read mA now. when i first connect, it will pause on 6.6mA (0.0066A) then jump to 200~300mA. it will do this for 30 seconds then hover off at 50~60 mA again.

Malaclypse
11-17-2009, 09:07 PM
Sounds like the turn on signal for your amplifier is tapped into a circuit that goes to that BCM connector you were mentioning earlier.

If you've pulled all the underhood fuses with no further drop in parasitic draw, then you should have it narrowed down. Aftermarket amps and caps can cause parasitic load issues.

alocaurd
11-17-2009, 09:11 PM
Sounds like the turn on signal for your amplifier is tapped into a circuit that goes to that BCM connector you were mentioning earlier.

If you've pulled all the underhood fuses with no further drop in parasitic draw, then you should have it narrowed down. Aftermarket amps and caps can cause parasitic load issues.

it seems odd to me still. yes, the turn on signal is from the head unit which is under the 2 pulled fuses, but power comes straight from the batter and it always drawing it seems. the funny part is that even with the amp and cap unplugged, i still have 0.5A draw, until i pull both BCM fuses (slots 3 and 4 under hood), which it goes down to 0.05A

alocaurd
11-17-2009, 09:32 PM
ok so i've pulled every other fuse with no difference, although i havent pulled relays. still 0.06A without fuses 3 and 4, and 0.6A with the fuses in...

so my next question would be: how do i test my bcm? unless im not completely right on this and there is something else i should do first? like i said in my first post, the current seems to drop when i unplug the middle connector.

Malaclypse
11-17-2009, 10:55 PM
Well, at this point its hard for me to be certain what's causing the draw without putting hands on the car myself.

You can eliminate the radio and amp by unpluging the head unit and leaving the BCM connected. Then verify the .5A draw. If the draw is still there then its in the BCM. If the draw is gone then its the radio or amp.

There's not really a way to test the BCM. One thing I've done in the past is to remove the module and open the case. Look for corossion on the circuit board. It'll show as a blue-ish powder on the glossy coating. Usually around the terminals for the connector pins.

alocaurd
11-17-2009, 11:24 PM
firstly, i pulled out both wiring grommets where i thought i may have stripped sometime to find them clean, so that is ruled out.

secondly, i will give unplugging the radio and amp a shot, and see if i can narrow this down further. i'll have a look inside the BCM as well if i find it to still be a problem.

now, if it comes down to it, i should have no problem swapping in a BCM from the boneyard correct? or am i year-specific? perhaps aaron will know this ;)

i appreciate all the help and input you guys have given, and tomorrow my fight continues hahah

Malaclypse
11-18-2009, 12:04 AM
firstly, i pulled out both wiring grommets where i thought i may have stripped sometime to find them clean, so that is ruled out.

secondly, i will give unplugging the radio and amp a shot, and see if i can narrow this down further. i'll have a look inside the BCM as well if i find it to still be a problem.

now, if it comes down to it, i should have no problem swapping in a BCM from the boneyard correct? or am i year-specific? perhaps aaron will know this ;)

i appreciate all the help and input you guys have given, and tomorrow my fight continues hahah

If memory serves, you -may- be able to swap in a BCM from a yard... but the problem is not knowing if it had similar issues. Beyond that I'd say that you'd be better off buying a new one... though I have gotten a few bad BCMs right out of the manufacturer box.

That and you need a Tech 2 to set the BCM options and configure the airbag module.

After all of that its just a matter of performing a Passlock learn.

AaronGTR
11-18-2009, 04:58 PM
Yeah, I have not had to swap any BCM's myself. I am pretty sure you need a tech2 to set it up though like Malaclypse said.

alocaurd
11-22-2009, 08:16 PM
well its been a while but i've checked the radio and whatnot and it's still the second connector of the BCM so unfortunately i'm going to bite the bullet and bring it in to a shop. hopefully i can cut down labor costs seeing how my car is already disassembled hahah. i'll let you know the final outcome hopefully by thursday.

Malaclypse
11-22-2009, 09:19 PM
Good luck cutting labor and the BCM isn't that hard to replace. Its the programming and setup that is most of the labor.

2000GAGT
01-18-2011, 10:03 PM
hey did you every get this one figured out? I have the same problem but most of my current draw is coming from the pink connector on the BCM, not the middle connector.

01GPGT
01-19-2011, 01:34 AM
they go off of book even if the car has no interior

but good luck on trying to get it fixed.

2000GAGT
01-20-2011, 09:17 PM
well in my case i definitely have an electrical gremlin. im drawing 90 mA (.090 A) and i narrowed most of the draw down to the pink C3 connector on the BCM. When removing this harness it dropped 60mA. I tried testing each pin connector individually in series for amps and the only pins showing up were three, all for door control but I could also hear the doors locks engaging when i connected my DVOM assuming thats why I have amp draw to the doors . Any one every hear of anything like this? im just leaning towards BCM failure since I checked Alldata and Identifix and found nothing for this.