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Hummer H3For the Hummer driver who wants the rugged look and off road capabilities of the Hummer, but in a smaller size and with a more fuel economy friendly engine.
well auto zone have that scanner than scan battery and stuff and they said my battery is charging find yet the code fail for alternator
I’ll check the fuse 32 today after work but those orange wire are under the fuse box? Cus they are covered with the black protector and when I took off the fuse box I didn’t see any damage but I’ll see if I can test again following the diagram after work today
Originally Posted by hummerz
You need a scanner that will scan Generator Battery Control Module (GBCM)
Whatever, I will guess the code B1390 and/or B1492?
Test at Under Hood Fuse Block (UHFB) fuse 32. Test at C125 terminal 16 Orange wire.
Trace wire from C125 to GBCM terminal C, look for open wire.
well auto zone have that scanner than scan battery and stuff and they said my battery is charging find yet the code fail for alternator
I’ll check the fuse 32 today after work but those orange wire are under the fuse box? Cus they are covered with the black protector and when I took off the fuse box I didn’t see any damage but I’ll see if I can test again following the diagram after work today
Yes, you have to pull them out of the loom to inspect (pic from internet, pointer showing damage to repair):
Yes, you have to pull them out of the loom to inspect (pic from internet, pointer showing damage to repair):
The GBCM is on the negative battery cable:
ahh I see I will double check it when I get home but I have that black protector all over around it when I pulled the fuse box yesterday . It’s all wires are covered like the 2nd pic
ahh I see I will double check it when I get home but I have that black protector all over around it when I pulled the fuse box yesterday . It’s all wires are covered like the 2nd pic
Check the fuse, and test at connector first. If you have to dig into the harness, the wire loom is split to access the wires, may need to pull off some tape. After your done, tuck the wires back into the loom and tape it up good.
Check the fuse, and test at connector first. If you have to dig into the harness, the wire loom is split to access the wires, may need to pull off some tape. After your done, tuck the wires back into the loom and tape it up good.
okay I’ll do that I’ll check everything and take that black cover around the wires to check the wires under the fuse box and also check the fuse and update
Out of curiosity, I just checked my voltage, parked at idle:
12.6v resting
11.4v cranking
15.1v startup
13.6v after 4 minutes( jumped to 13.9v when I turned accessories/lights on)
12.8v after 10 minutes (with all accessories off)
My GBCM is working properly.
If you research your dic error, you will see many posts about GBCM bypass, I don't recommend!
The GM regulated voltage control system can vary from 11.5 –15.5 volts. As with other systems in use today, the GM system has a fuel economy mode, which is designed to lower the charging system voltage by reducing the alternator field strength.Technicians often diagnose this mode as a faulty charging system, only to find out that the vehicle operates the same even with new parts installed. Simply applying maximum load to the vehicle’s electrical system will cause the PCM/ECM to respond, raising charging system voltage.
GM also designed this system to identify battery sulfation. In response, the PCM/ECM will command the charging system’s voltages to increase to as high as 15.5 volts, even when there’s no electrical load. Sulfation mode will typically last less than five minutes at a time, so, as the timer expires, the system will return to normal charging operation.
Out of curiosity, I just checked my voltage, parked at idle:
12.6v resting
11.4v cranking
15.1v startup
13.6v after 4 minutes( jumped to 13.9v when I turned accessories/lights on)
12.8v after 10 minutes (with all accessories off)
My GBCM is working properly.
If you research your dic error, you will see many posts about GBCM bypass, I don't recommend!
The GM regulated voltage control system can vary from 11.5 –15.5 volts. As with other systems in use today, the GM system has a fuel economy mode, which is designed to lower the charging system voltage by reducing the alternator field strength.Technicians often diagnose this mode as a faulty charging system, only to find out that the vehicle operates the same even with new parts installed. Simply applying maximum load to the vehicle’s electrical system will cause the PCM/ECM to respond, raising charging system voltage.
GM also designed this system to identify battery sulfation. In response, the PCM/ECM will command the charging system’s voltages to increase to as high as 15.5 volts, even when there’s no electrical load. Sulfation mode will typically last less than five minutes at a time, so, as the timer expires, the system will return to normal charging operation.
so does that mean my alternator is bad cus it’s pushing more power??
how can I make it take control again? Or what’s the fix?
Look at the wiring diagram posted above,#32 fuse is the REGULATED VOLTAGE CONTROL(RVC) VSENSE+.
Get your meter out and check voltage at the fuse and check terminal C(A-orange, B-grey, C-orange) :
