Elecrical problem
#1
06-01-2011, 05:13 PM
Elecrical problem
Hello guys, I recently purchased a 2003 yellow H2. I really like the car but just noticed that there is a problem with the electrical system. When the key is off the ignition the interior lights wont turn on, the power locks wont work and even the stereo will not eject disc, etc. There's basically no power in the interior, once the key is in the ignition and in the on position everything works just fine. I don't really know what to check for. Except for the BCM but I wouldn't know where to start there either. Thank you in advance for your help. 
#3
06-01-2011, 11:45 PM
I also have an 03 H2, love mah Hummer!
Had a similar problem which I errantly ignored for a bit, major mistake. It ultimately seems to have affected other modules in the truck with i've had to deal with.
In my case it was a bad BCM, which is the Body Control Module. It is located in the passenger kick panel. Just for a reference the BCM is tied directly to the following systems in your vehicle:
• Automatic door locks
• Battery protection
• Chimes
• Compass/mini-trip support
• Courtesy lamps
• BCM diagnostic support
• Door lock inhibit
• Headlamp time delay
• Ignition key lamp
• Illuminated entry
• Instrument panel dimming
• Mechanical instrument cluster support
• Power door locks (with/without remote keyless entry)
• Sliding door memory lock
• Vehicle Theft Security system (VTSS)
• Windshield wipers / washers (front and rear)
Depending on your environment it may have some corrosion on the pins or who knows. Might be a simple fix, it may require replacement.
Had a similar problem which I errantly ignored for a bit, major mistake. It ultimately seems to have affected other modules in the truck with i've had to deal with.
In my case it was a bad BCM, which is the Body Control Module. It is located in the passenger kick panel. Just for a reference the BCM is tied directly to the following systems in your vehicle:
• Automatic door locks
• Battery protection
• Chimes
• Compass/mini-trip support
• Courtesy lamps
• BCM diagnostic support
• Door lock inhibit
• Headlamp time delay
• Ignition key lamp
• Illuminated entry
• Instrument panel dimming
• Mechanical instrument cluster support
• Power door locks (with/without remote keyless entry)
• Sliding door memory lock
• Vehicle Theft Security system (VTSS)
• Windshield wipers / washers (front and rear)
Depending on your environment it may have some corrosion on the pins or who knows. Might be a simple fix, it may require replacement.
#4
06-03-2011, 01:32 AM
Thank you for the post Gleamor, will the power locks work when the ignition is on if the BCM was shot? One more thing, i know my hummer had an aftermarket alarm connected in the past, do you think that could be the cause of the problem? Thank you guys again for all the help
#5
06-03-2011, 12:26 PM
The BCM is operational when battery power is supplied to the module. Ignition switch power is needed for ignition switch functions. So Yes the power locks would typically work with the ignition in the ON position even if the BCM is faulty.
An aftermarket alarm connected in the past...
That adds a couple variables, based on your statement I would assume it is NOT connected now. This creates the following list of variables
Was the alarm disconnected properly? If Yes than no it would not be a factor. If No than its possible that it caused the BCM to fault
If the alarm is still installed is it faulty? If Yes than it could be a factor and removal would be the first step. If No it is not faulty and still functions properly was it installed properly?
I would sum it up by saying unless your aftermarket alarm was installed improperly, or the aftermarket alarm failed at some point there is a chance that it interrupted the logic saved in the BCM. It is however very unlikely if it was installed / uninstalled by a reputable shop. Simply disconnecting a faulty aftermarket alarm is always a recipe for problems.
In general a properly installed aftermarket alarm is not going to cause any problems at all and are a very good addition to your Hummer. (I have a Viper installed in mine).
If you have some skills with electronics and want to test the BCM yourself (Warning, if your not very proficient in electronics do NOT proceed. I will not be held responsible for what happens to you or your Hummer)
Can test the following for voltage with key in position 1 and position 2
Start testing in position 2, this will be your control voltage, move to position 1 and validate that the same voltage exists on the following:
Power Lock lt. blue - blk plg, pin A11
Power unlock dk. blue - black plug, pin A12
Dome Supervision white - BCM, black plug, pin A46
Also check voltage on PCM (Powertrain Control Module) blue plug pin 48 the PCM is located on the passenger side firewall under the hood.
This would be a first step for me, if you have power to the BCM in position 1 than it indicates that the BCM has a likely logic fault.
The good news is that if the BCM has a fault its an easy part to come by and easy to replace. $230ish dollars unless you go to the dealer where you will spend upwards of $400
An aftermarket alarm connected in the past...
That adds a couple variables, based on your statement I would assume it is NOT connected now. This creates the following list of variables
Was the alarm disconnected properly? If Yes than no it would not be a factor. If No than its possible that it caused the BCM to fault
If the alarm is still installed is it faulty? If Yes than it could be a factor and removal would be the first step. If No it is not faulty and still functions properly was it installed properly?
I would sum it up by saying unless your aftermarket alarm was installed improperly, or the aftermarket alarm failed at some point there is a chance that it interrupted the logic saved in the BCM. It is however very unlikely if it was installed / uninstalled by a reputable shop. Simply disconnecting a faulty aftermarket alarm is always a recipe for problems.
In general a properly installed aftermarket alarm is not going to cause any problems at all and are a very good addition to your Hummer. (I have a Viper installed in mine).
If you have some skills with electronics and want to test the BCM yourself (Warning, if your not very proficient in electronics do NOT proceed. I will not be held responsible for what happens to you or your Hummer)
Can test the following for voltage with key in position 1 and position 2
Start testing in position 2, this will be your control voltage, move to position 1 and validate that the same voltage exists on the following:
Power Lock lt. blue - blk plg, pin A11
Power unlock dk. blue - black plug, pin A12
Dome Supervision white - BCM, black plug, pin A46
Also check voltage on PCM (Powertrain Control Module) blue plug pin 48 the PCM is located on the passenger side firewall under the hood.
This would be a first step for me, if you have power to the BCM in position 1 than it indicates that the BCM has a likely logic fault.
The good news is that if the BCM has a fault its an easy part to come by and easy to replace. $230ish dollars unless you go to the dealer where you will spend upwards of $400
#6
06-21-2011, 08:53 AM
more than likely bcm ,on my 03 its above the steering colum not on passenger side.these bcm's are junk and in a real bad spot to replace. Dont forget if you replace it yourself you will need to tow it to the dealer to program.the truck wont start because of the security [passlock system ] is also part of the bcm.been there done that ...
