Pontiac Repair: 2007 montana sv6 charging system, pontiac montana sv6, pontiac montana

Question
hi i have a 2007 Pontiac Montana SV6 and the battery light came on and the battery charging system failure started coming across my display panel i removed the alternator and brought it to a shop to be tested and they said it was fine so i put it back in and still the same thing it wont charge my battery now it is saying charging system failure and battery saver activated could you please give me some help with this i am stumped

Answer
Hi Ed:

the charging system on that Van is pretty complex. Usually the issues are Alternator related BUT it can be any number of things else wrong with it. Ther is a battery charging sensor on the battery cable. The body control module and the engine control module they all play a part in the charging of the battery. so any of those components can be bad or the wring between the components. Thus is not a type of an issue that can be Guessed at due to the components in the system. in a nut shell the voltage sensor doe just that it send a signal to the body control module the body control module sends a signal to the engine contorl module and the engine control module turns the alternator on. Seems simple but it's really not. good luck :)