2007 Montana SV 6 draining the battery

[sonyblue]

Hello to all!
I have an 2007 Pontiac Montana SV6 that wont start in the cold days. Here in Calgary we have a very cold weather this year with temperature going easily under -25 C. My car even plugged all night won't start at all in the morning.
This is the second battery on the vehicle, an aftermarket Motomaster way more powerful than the factory one.
If I connect the battery charger it will take no longer than 10 min to be able to start the vehicle.
Last spring the car was in a GM dealership for the same problem and they could not find anything wrong with the charging system and they sent me a letter stating that my alternator is "intelligent" and will adjust the charge accordingly with the load.
During summer at the return from my 1 week vacation I had the surprise to see my car was completely dead so I decide to change the battery... Now when the cold weather started the same thing is happening. All dash board instruments are going crazy, when you turn the key to start the engine, the horn is starting and all the gauges and dashboard lights are going nuts. You can hear relays and parasitic noise from the radio and the car won't start.
As I said 10-15 min on the charger and after on "boost assist" are enough to start the beast. I did all the parasitic tests with my multimeter and couldn't find anything.
I really need some advice before I will send the car back to dealership to find out how "intelligent" is my alternator and how shitty is my ECM.
Can somebody tell me if this is a generic problem with Pontiac Vans made after 2005, cause before I had a 2001 Montana that never did this.
Thanks

 

[skeeter]

Hello to all!
I have an 2007 Pontiac Montana SV6 that wont start in the cold days. Here in Calgary we have a very cold weather this year with temperature going easily under -25 C. My car even plugged all night won't start at all in the morning.
This is the second battery on the vehicle, an aftermarket Motomaster way more powerful than the factory one.
If I connect the battery charger it will take no longer than 10 min to be able to start the vehicle.
Last spring the car was in a GM dealership for the same problem and they could not find anything wrong with the charging system and they sent me a letter stating that my alternator is "intelligent" and will adjust the charge accordingly with the load.
During summer at the return from my 1 week vacation I had the surprise to see my car was completely dead so I decide to change the battery... Now when the cold weather started the same thing is happening. All dash board instruments are going crazy, when you turn the key to start the engine, the horn is starting and all the gauges and dashboard lights are going nuts. You can hear relays and parasitic noise from the radio and the car won't start.
As I said 10-15 min on the charger and after on "boost assist" are enough to start the beast. I did all the parasitic tests with my multimeter and couldn't find anything.
I really need some advice before I will send the car back to dealership to find out how "intelligent" is my alternator and how shitty is my ECM.
Can somebody tell me if this is a generic problem with Pontiac Vans made after 2005, cause before I had a 2001 Montana that never did this.
Thanks

Hello,

My name is Scott and I am having the exact same issues with my 07 Montana. I was wondering if you ever found a solution to this problem? I am about to replace the battery with something stronger with hopes it will correct the issue. If you have the answer I would love to hear it.

Thanks,
Scott

 

[sergeimoskva]

Hi ! @ All
Most likely you drain voltage.
Perhaps the problem due to a bad starter that was causing the battery cable to short out on the housing of the starter. Or the charging relay switch located on the main fuse panel above the battery. Or relay (IGN MAIN) faulty ( The stamped on top of the grey square relay ).Relay starts getting weak, it causes a constant current draw even with the ignition in the off position.
I would say check open circuit current drain with everything as is, then pull the main ignition relay . I'm guessing you'll see a marked drop in current draw.
Try it. Good luck!

 

[dad59]

BCM malfuction was my problem, everything was goin crazy, finally my battery started draining when radio lights stayed on

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[crash5456]

my 2007 did the same thing, found that the wiper on rear hatch was always running without moving the wiper. I couldn't hear it till I was standing behind my van.