Alternator BCM question
Thread Starter
Burning Brakes
Joined: Dec 2007
Posts: 754
Likes: 2
From: Redondo Beach California
Alternator BCM question
Guys,
Quick question, does the BCM send signal to the alternator to regulate voltage?
Im having bad voltage spikes 18 volts and im trying to isolate it.
Thanks
Quick question, does the BCM send signal to the alternator to regulate voltage?
Im having bad voltage spikes 18 volts and im trying to isolate it.
Thanks
Race Director
Joined: Sep 2009
Posts: 11,338
Likes: 2,437
From: Eastern
The alternator has an internal voltage regulator, which could be going bad.
Check all you connections, clean posts and contact points on the battery and the alternator. Also check the ground connection.
If all this is Good, then you may want to get the alternator tested.
I'm not sure what year your car is, but the 07's supposedly had some alternator issues. Many were replaced because of voltage high spikes.
See this link
https://www.corvetteforum.com/forums...lts-ideas.html
Good luck
Check all you connections, clean posts and contact points on the battery and the alternator. Also check the ground connection.
If all this is Good, then you may want to get the alternator tested.
I'm not sure what year your car is, but the 07's supposedly had some alternator issues. Many were replaced because of voltage high spikes.
See this link
https://www.corvetteforum.com/forums...lts-ideas.html
Good luck
Melting Slicks
Joined: Aug 2006
Posts: 2,475
Likes: 97
From: KY/TN
St. Jude Donor '13-'14-'15-'16
Are you getting a high voltage message in your instrument panel?
The BCM is essentially a gateway and will deactivate electrical loads if the generator is unable to maintain system voltage, but the generator turn-on signal is sent from the engine control module (ECM).
"When the engine is running, the generator turn-on signal is sent to the generator from the engine control module (ECM), turning on the regulator. The generator's voltage regulator controls current to the rotor, thereby controlling the output voltage. The rotor current is proportional to the electrical pulse width supplied by the regulator. When the engine is started, the regulator senses generator rotation by detecting AC voltage at the stator through an internal wire. Once the engine is running, the regulator varies the field current by controlling the pulse width. This regulates the generator output voltage for proper battery charging and electrical system operation. The generator F terminal is connected internally to the voltage regulator and externally to the ECM. When the voltage regulator detects a charging system problem, it grounds this circuit to signal the ECM that a problem exists. The ECM monitors the generator field duty cycle signal circuit. The system voltage sense circuit receives B+ voltage that is Hot At All Times through the HORN/ALT SENSE fuse in the underhood junction block. This voltage is used by the regulator as the reference for system voltage control. On vehicles that use a sense circuit connected to the voltage regulator, this circuit must be operating properly for the charging system to work correctly, when there is a charging system concern all circuits at the generator should be tested. "
The BCM is essentially a gateway and will deactivate electrical loads if the generator is unable to maintain system voltage, but the generator turn-on signal is sent from the engine control module (ECM).
"When the engine is running, the generator turn-on signal is sent to the generator from the engine control module (ECM), turning on the regulator. The generator's voltage regulator controls current to the rotor, thereby controlling the output voltage. The rotor current is proportional to the electrical pulse width supplied by the regulator. When the engine is started, the regulator senses generator rotation by detecting AC voltage at the stator through an internal wire. Once the engine is running, the regulator varies the field current by controlling the pulse width. This regulates the generator output voltage for proper battery charging and electrical system operation. The generator F terminal is connected internally to the voltage regulator and externally to the ECM. When the voltage regulator detects a charging system problem, it grounds this circuit to signal the ECM that a problem exists. The ECM monitors the generator field duty cycle signal circuit. The system voltage sense circuit receives B+ voltage that is Hot At All Times through the HORN/ALT SENSE fuse in the underhood junction block. This voltage is used by the regulator as the reference for system voltage control. On vehicles that use a sense circuit connected to the voltage regulator, this circuit must be operating properly for the charging system to work correctly, when there is a charging system concern all circuits at the generator should be tested. "
