Tracking down a parasitic draw

[Poisond281]

Hey all,

I've watched a few videos on how to properly test for amperage draws in the fuse box, but I'm fairly certain the aftermarket alarm that came with the car is causing the issue. The car has eaten two batteries since I bought it, and I'd like to get the issue sorted. Are aftermarket alarm installations fairly similar for SN95s? Reason I ask is there a certain size fuse I should focus on first? Any potential impacts on removing said alarm from the car that I would need to take into consideration?

I'm no electrician by any stretch of the imagination so any help to narrow down the draw would be greatly appreciated.

 

[MG0h3]

Could always just disconnect the alarm no?

But ya.

Disconnect the neg battery terminal.

Hook amp meter in series between cable end and neg batt terminal.

Under 250ma or 1/4 of an amp is usually ok.


Sent from my iPhone using svtperformance.com

 

[Vinnie_B]

Hey all,

I've watched a few videos on how to properly test for amperage draws in the fuse box, but I'm fairly certain the aftermarket alarm that came with the car is causing the issue. The car has eaten two batteries since I bought it, and I'd like to get the issue sorted. Are aftermarket alarm installations fairly similar for SN95s? Reason I ask is there a certain size fuse I should focus on first? Any potential impacts on removing said alarm from the car that I would need to take into consideration?

I'm no electrician by any stretch of the imagination so any help to narrow down the draw would be greatly appreciated.

Find the name/info of the aftermarket alarm on the controller under your dash. Than get install instructions off internet to disconnect it. Take an amp reading before and after to see the draw difference. Keep us updated.

 

[L-Bronco]

Hey all,

I've watched a few videos on how to properly test for amperage draws in the fuse box, but I'm fairly certain the aftermarket alarm that came with the car is causing the issue. The car has eaten two batteries since I bought it, and I'd like to get the issue sorted. Are aftermarket alarm installations fairly similar for SN95s? Reason I ask is there a certain size fuse I should focus on first? Any potential impacts on removing said alarm from the car that I would need to take into consideration?

I'm no electrician by any stretch of the imagination so any help to narrow down the draw would be greatly appreciated.

Hi, The most effective way to track down a parasitic loss in a car is by measuring the voltage drop across the fuses. If there is current flow through a fuse, the voltage on the supply side of the fuse will be slightly higher than the protected side. (A fuse uses a bit of current while its load is on, and it warms up a little. If the current gets too high, it will melt. That being said, just use a DC voltmeter and put one lead on either side of each fuse, starting with the maxi fuses. With everything off, any fuses with a voltage drop have current flowing. Once you find the culprit, figure out what circuit it is and go from there. If you suspect the alarm, start there for sure.
Couple things to remember, The network will need some time to power down completely, (This can take up to 15 min in some cases) Also, every time you pull a fuse or open a door, the power down starts all over.
To find max allowable drain, take the reserve capacity of your battery (its in min) and divide by 4, the number is the max draw in milliamps.
(120 min reserve =30ma max draw) That one is from GM service info, but its a good guide all around)
Hope that helps.
Cheers!

 

[Vinnie_B]

This is a good tool to have for issue's like your having now. Easy to use even for a beginner. You can plug into each circuit to test for draw and isolate. Your under the dash SJB fuse panel is were you want to look.

 

[L-Bronco]

A much quicker, but far less accurate method for parasitic loss testing is a thermal camera. (You need a pretty good one and it only works well with larger draws)
Just point it at the fuse panels (Fairly close) and the hottest one is the biggest draw.
If you suspect the alarm system, point it directly at the module. (Anything electrical that is on, that kills a battery in one or 2 days, will be noticeably warm).
Good luck!

 

[Poisond281]

Thanks for all the suggestions everyone. Will climb up under the dash tomorrow to see if I can locate the alarm module. Hopefully locating it and removing it will kill the power draw. Will keep everyone posted!

 

[L-Bronco]

Thanks for all the suggestions everyone. Will climb up under the dash tomorrow to see if I can locate the alarm module. Hopefully locating it and removing it will kill the power draw. Will keep everyone posted!

Happy Hunting!!

 

[shurur]

Happy Hunting!!

Good ideas from you!
I always know its a good idea when I wish that I had thought of it.

 

[hotcobra03]

On my 03 that Alarm thing went bad,,caused a no start issue
Just un plugged it and car worked fine,

I was hoping it was the issue on mine ,where if car sat for a few days battery was dead ,

I still have to disconnect it ,

 

[01silverstang]

I'm in the same boat, only I have a weird step thrown in...

The battery in my Cobra has been a little weak since I purchased it, and appeared to be a junkyard recycled one. It died shortly before Christmas, which meant no power locks and Christmas presents in the car. Absentmindly tried to jump it to get them out, and accidentally attached the jumper cables backwards. Within a few seconds I saw the cable get very hot and removed them.

Fast forward to last weekend, grabbed a Walmart Everstart and within a day it was down to 6-7v (never attempted to start the car, but the chime and dash and everything came on when put to ACC power on). I removed the battery and put it on a float charger and it was at 12.9v the next morning, so I'm assuming the battery is good but that I had a draw. Maybe the jumper cable thing is nothing and it was just a dome light, or cell phone charger left in the cigarette lighter... but I will be testing for draw this weekend as well.

 

[L-Bronco]

I'm in the same boat, only I have a weird step thrown in...

The battery in my Cobra has been a little weak since I purchased it, and appeared to be a junkyard recycled one. It died shortly before Christmas, which meant no power locks and Christmas presents in the car. Absentmindly tried to jump it to get them out, and accidentally attached the jumper cables backwards. Within a few seconds I saw the cable get very hot and removed them.

Fast forward to last weekend, grabbed a Walmart Everstart and within a day it was down to 6-7v (never attempted to start the car, but the chime and dash and everything came on when put to ACC power on). I removed the battery and put it on a float charger and it was at 12.9v the next morning, so I'm assuming the battery is good but that I had a draw. Maybe the jumper cable thing is nothing and it was just a dome light, or cell phone charger left in the cigarette lighter... but I will be testing for draw this weekend as well.

When you connect booster cables in reverse, any live circuit with a diode in it will begin to conduct. The largest being in the alternator rectifier, (there are 6 big ones in there) the high current can overheat them causing one to short out and have a draw.
disconnect the big lead at the alternator before you hook up your battery again and see if it still draws. If it is killing a new battery in under a day, the draw is pretty big. If it still draws, several of the methods in this thread should help you. Good luck!
Cheers

 

[01silverstang]

When you connect booster cables in reverse, any live circuit with a diode in it will begin to conduct. The largest being in the alternator rectifier, (there are 6 big ones in there) the high current can overheat them causing one to short out and have a draw.
disconnect the big lead at the alternator before you hook up your battery again and see if it still draws. If it is killing a new battery in under a day, the draw is pretty big. If it still draws, several of the methods in this thread should help you. Good luck!
Cheers

Which connector on the alternator? If I only connect the positive and then put my multimeter between the negative cable and negative post to measure draw and see one, and then unplug the alternator and test again and don't... that should confirm alternator is the issue?

 

[L-Bronco]

Mainly the big lead from the battery, BK\OG . But feel free to disconnect both.
Note: check the fuse link, it often melts when the system is boosted backwards. If that happened, you will need to change it and your draw will be elsewhere, but the methods in this thread should help you out.
Hope this helps

 

[L-Bronco]

And yes, if your draw stops when you unplug something, whatever you just disconnected is causing the draw.
Cheers

 

[01silverstang]

And yes, if your draw stops when you unplug something, whatever you just disconnected is causing the draw.
Cheers

I will try that, I had already replaced the fusible links last year... and they looked fine. Nothing obvious with damage.

 

[L-Bronco]

Awesome!
Good luck then!

 

[01silverstang]

Update for mine:

2.7 amp draw measured at battery, unplugged the alternator and retested and had zero amp draw… will be ordering a new alternator. Hope this helps someone else.