100 mA vs 30 mA
Thread Starter
Heel & Toe
Joined: Sep 2012
Posts: 15
Likes: 2
From: Virginia
100 mA vs 30 mA
Over the past 6 months I've had battery issues and assumed it was from not using my 2000 coupe enough. Sadly, it has at times, not been driven for a month. The battery was still under a 30 month warranty and the local Chevy dealer replaced it. I don't know if they tested for any specific drain issue.
After the new battery died, a friend came over with an amp meter and one by one pulled fuses located by the battery. No matter what was pulled it still registered 100 mA. He researched and believes that "normal" should only be 30 mA.
At the time, neither of us realized there's another fuse box at the passenger foot well. So, that will be tested next week. He will also test the alternator.
So is there anything else he can check aside from what I've already mentioned? And is 30mA what should be normal for this year?
Thanks!
After the new battery died, a friend came over with an amp meter and one by one pulled fuses located by the battery. No matter what was pulled it still registered 100 mA. He researched and believes that "normal" should only be 30 mA.
At the time, neither of us realized there's another fuse box at the passenger foot well. So, that will be tested next week. He will also test the alternator.
So is there anything else he can check aside from what I've already mentioned? And is 30mA what should be normal for this year?
Thanks!
Thread Starter
Heel & Toe
Joined: Sep 2012
Posts: 15
Likes: 2
From: Virginia
Here is a cut and paste from a thread by Bill Curlee the Forums resident electrical wizard:
The correct BCM current draw should be 30 Milliamps or less. Most C5 run around 25ma
but I have see some as low as 15 ma.
Leave the engine compartment fuse box for last and start with the passengers compartment
box first. Pull the power seat breakers FIRST! The power seats have a tendancy stay on
and cause this issue.
Also pull the fuses for the Bose system amp.
Examine the car in the dark for lights staying ON.
Once you prove the interior circuits good,,, check the headlight circuits, and then test
the current draw of the alternator.
Look at my electrical stickey. I think I cover this in detail in that post.
There are several COMMON things that cause excessive current draw
-Seat multifunction switch & Lumbar Switch
- Bose Amp relay stuck on
- Alternator didoes bad and drawing current
- Headlight control module bad
- Interior light on (check in the dark)
- Added aftermarket accessory not shutting off
Take note of his list of common causes of current drain and perhaps check a few of those before resuming the fuse pulling.
The correct BCM current draw should be 30 Milliamps or less. Most C5 run around 25ma
but I have see some as low as 15 ma.
Leave the engine compartment fuse box for last and start with the passengers compartment
box first. Pull the power seat breakers FIRST! The power seats have a tendancy stay on
and cause this issue.
Also pull the fuses for the Bose system amp.
Examine the car in the dark for lights staying ON.
Once you prove the interior circuits good,,, check the headlight circuits, and then test
the current draw of the alternator.
Look at my electrical stickey. I think I cover this in detail in that post.
There are several COMMON things that cause excessive current draw
-Seat multifunction switch & Lumbar Switch
- Bose Amp relay stuck on
- Alternator didoes bad and drawing current
- Headlight control module bad
- Interior light on (check in the dark)
- Added aftermarket accessory not shutting off
Take note of his list of common causes of current drain and perhaps check a few of those before resuming the fuse pulling.
Instructor
Joined: Dec 2012
Posts: 191
Likes: 23
From: Louisville KY
When checking the amp draw you need to make sure the car goes into sleep mode. If you are simply pulling the fuses and checking the current, it probably is not in sleep mode. I can't remember how many minutes it takes for the car to go into sleep mode but you do need to me mindful or you will get an incorrect reading.
Thread Starter
Heel & Toe
Joined: Sep 2012
Posts: 15
Likes: 2
From: Virginia
When checking the amp draw you need to make sure the car goes into sleep mode. If you are simply pulling the fuses and checking the current, it probably is not in sleep mode. I can't remember how many minutes it takes for the car to go into sleep mode but you do need to me mindful or you will get an incorrect reading.
Thread Starter
Heel & Toe
Joined: Sep 2012
Posts: 15
Likes: 2
From: Virginia
The BCM monitors activity of the car when there are currents being drawn by electrical activity in the car. Things like interior lights on, door open, hood open and underhood light on , accessories such as cell phone charging from cigarette lighter connection, or radar detector on etc.....
Once all current drains are removed the BCM enters "sleep mode" where it drops the current that it uses for these monitor functions to a lower level of 30Ma or less. It should take several minutes for the BCM to enter sleep. It it take more than say 15 minutes then there is one or more circuits consuming power that is preventing the BCM from dropping its own power consumption.
So once you connect up your monitor device, do what ever you need to cause things like interior lights, underhood light, cell phone or other after market devices from drawing power.
There is an automatic turn off of power for certain devices like foot well or trunk lights, underhood light, glove box or vanity mirror lights or interior mirror flood light but that takes 15 minutes or so to occur. Those current draws will prevent the BCM from entering sleep mode until several minutes after that..
Once all current drains are removed the BCM enters "sleep mode" where it drops the current that it uses for these monitor functions to a lower level of 30Ma or less. It should take several minutes for the BCM to enter sleep. It it take more than say 15 minutes then there is one or more circuits consuming power that is preventing the BCM from dropping its own power consumption.
So once you connect up your monitor device, do what ever you need to cause things like interior lights, underhood light, cell phone or other after market devices from drawing power.
There is an automatic turn off of power for certain devices like foot well or trunk lights, underhood light, glove box or vanity mirror lights or interior mirror flood light but that takes 15 minutes or so to occur. Those current draws will prevent the BCM from entering sleep mode until several minutes after that..
Thread Starter
Heel & Toe
Joined: Sep 2012
Posts: 15
Likes: 2
From: Virginia
Thanks everyone for your help! Reading today (after sleep mode) was 24 mA. Lessons learned: Drive the car more. When not able to take it for a spin, apply battery tender.
Now onto checking grounds per Bill Curlee's electrical write up. This forum ROCKS!
Now onto checking grounds per Bill Curlee's electrical write up. This forum ROCKS!
