2009 Pontiac Montana sv6 3.9L BCM problems?
12-04-2019, 11:27 PM
#21
If I wasn't already, I am certainly now above my pay grade. With this additional information, I can only guess that the sheer number of codes among all the vehicle management systems, with the addition of the several specific communication protocol codes, indicates that the interface among the ECM/TCM/BCM has gone haywire. In other words, it seems unlikely that each of the P codes represents an actual malfunction; there are simply too many for that to be realistic. Rather, it is more likely that the system as a whole is on the fritz and all kinds of misbegotten codes are popping up everywhere.
If I'm on the right track, perhaps someone can identify the likely how/why and potential fix for the problem. But with the additional info, the problem has been revealed as exponentially beyond what a simple BCM replacement could fix. Or so it seems to me.
If I'm on the right track, perhaps someone can identify the likely how/why and potential fix for the problem. But with the additional info, the problem has been revealed as exponentially beyond what a simple BCM replacement could fix. Or so it seems to me.
12-05-2019, 09:39 AM
#22
On the other hand, if the BCM is causing the codes with bad signals on the bus then it could still be a bad BCM. The telling factor here might be that the original BCM doesn't communicate but the used replacement does. Unlike a typical computer network, the car's system is peer-to-peer so there is no central "server" (single point of failure) which could be generating faults like that and the chance that all of those modules actually have so many problems at the same time is nearly impossible (you haven't driven your vehicle into a pond have you?) This sounds like what we call a "broadcast storm" on an Ethernet network - a single faulty network card can generate so much invalid traffic that other devices on the network go offline because they can't handle it and the entire network becomes basically unusable.
One way to check would be to remove the BCM, clear all the codes, install the used BCM and see if the codes come back. I would assume not. Then plug in the original BCM and again check for codes. I suspect you'll see them all return at that point, proving that it is actually the BCM causing them.
One way to check would be to remove the BCM, clear all the codes, install the used BCM and see if the codes come back. I would assume not. Then plug in the original BCM and again check for codes. I suspect you'll see them all return at that point, proving that it is actually the BCM causing them.
12-05-2019, 10:41 AM
#23
Good to hear your opinion WhiteBird, I think that is excellent logic. I will give it a try as soon as the snow lets up a bit. Hoping what you suspect will be proven out. A HUGE thank you!!
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G Atsma (12-05-2019)
12-16-2019, 09:27 PM
#24
Hello all.
It has been quite some time since I posted more results. The reason is that I ran into problems interpreting my new scanners test results which I'll get into before I discuss my attempt at implementing Whitebird's suggestion of putting the old original bcm back in.
The scanner has two types of scan selections, "quick" and "control module". Each of the scans produced a list of the number of "faults" for each module detected. Any module with detected faults had the numerical number of those faults listed in red. Further details on those faults could be accessed by highlighting the module concerned and hit the enter button. For example, a quick scan would list 4 faults for the ecm. In order to find the trouble codes associated with these four faults you are given two choices. One of the choices was to select a "report" key. Using that procedure produced a mere 4 trouble codes. The second choice was to highlight the ecm module faults line and then hit the enter key. Instead of just producing 4 trouble codes there were close to 70!! This really had me confused because this was the case for all modules that indicated a small number of faults, ie hitting the "report key" always showed a number of faults that agreed with the small number indicated in red but when highlighting the module line and then hitting "enter" key the number of faults was always much much higher!! I have been trying to get an answer to this from the scanner company but am getting nowhere. Their user's
manual is just useless, just adds more confusion. I have another gm vehicle which is working just fine so I decided to scan it to see what would happen. I could not believe what I found!! No trouble code faults were reported for ANY module after a "quick scan" or a "control module" scan. When I hit the report key for the "quick scan" of the ecm I received NO trouble codes. Yet after highlighting the ecm scan line for either the "quick scan" or the "module scan" result, and then hitting the enter key, I teceived a list of close to 60 trouble codes. What a shock! It is the same type of thing I'm getting with the van!! Does anyone have any thoughts on these "weird" happenings. I feel like Clint Eastwood in the movie Space Cowboys when it came to him using installation instructions. Lol.
Anyway I have been fumbling around on my own trying to figure out how to interpret all of this. Because of all this confusion I wasn't able to understand why when I tried to erase the codes it did not seem to do anything to these long lists of trouble codes. I couldn't make ANY sense of this. Because of all the input you guys have given me I decided to take the plunge and purchase a refurbished bcm from Rockauto. It arrived by Fedex in two days and I couldn't wait to install it. Upon installation It performed just as the one I picked up from the wrecker, ie the instrument panel icons including the "locked out" icon lit up and the radio was "locked". Also the fob worked to remotely lock and unlock the doors. I noticed the air bag icon was now lit up whereas previously it never appeared, either with the old original faulty bcm or the bcm I picked up at the wreckers. However I could not start the van so I tried a procedure of turning the ignition key on and off three times which was supposed to remove the "locked out " icon and this should allow me to start the van. Much to my delight it was successful!!
A "quick scan" now produces the following codes
Bcm: C0278 - brake pedal pos'n sensor not calibrated
C0283 - brake pedal pos'n sensor circuit low
Supp Inflation restraint: B1001 - option config error
My radio is still locked and some instrument panel lights do not work. Hopefully having the bcm programmed will solve these issues plus the airbag icon. The main thing is that I can now drive the van and will not have to tow it to program the bcm.
PS Does anyone have any idea why the number of codes is sky high (up to 70 or so for the ecm), even for my G5 which is working just fine and shows no code faults when I choose the report option after a quick scan.
.
It has been quite some time since I posted more results. The reason is that I ran into problems interpreting my new scanners test results which I'll get into before I discuss my attempt at implementing Whitebird's suggestion of putting the old original bcm back in.
The scanner has two types of scan selections, "quick" and "control module". Each of the scans produced a list of the number of "faults" for each module detected. Any module with detected faults had the numerical number of those faults listed in red. Further details on those faults could be accessed by highlighting the module concerned and hit the enter button. For example, a quick scan would list 4 faults for the ecm. In order to find the trouble codes associated with these four faults you are given two choices. One of the choices was to select a "report" key. Using that procedure produced a mere 4 trouble codes. The second choice was to highlight the ecm module faults line and then hit the enter key. Instead of just producing 4 trouble codes there were close to 70!! This really had me confused because this was the case for all modules that indicated a small number of faults, ie hitting the "report key" always showed a number of faults that agreed with the small number indicated in red but when highlighting the module line and then hitting "enter" key the number of faults was always much much higher!! I have been trying to get an answer to this from the scanner company but am getting nowhere. Their user's
manual is just useless, just adds more confusion. I have another gm vehicle which is working just fine so I decided to scan it to see what would happen. I could not believe what I found!! No trouble code faults were reported for ANY module after a "quick scan" or a "control module" scan. When I hit the report key for the "quick scan" of the ecm I received NO trouble codes. Yet after highlighting the ecm scan line for either the "quick scan" or the "module scan" result, and then hitting the enter key, I teceived a list of close to 60 trouble codes. What a shock! It is the same type of thing I'm getting with the van!! Does anyone have any thoughts on these "weird" happenings. I feel like Clint Eastwood in the movie Space Cowboys when it came to him using installation instructions. Lol.
Anyway I have been fumbling around on my own trying to figure out how to interpret all of this. Because of all this confusion I wasn't able to understand why when I tried to erase the codes it did not seem to do anything to these long lists of trouble codes. I couldn't make ANY sense of this. Because of all the input you guys have given me I decided to take the plunge and purchase a refurbished bcm from Rockauto. It arrived by Fedex in two days and I couldn't wait to install it. Upon installation It performed just as the one I picked up from the wrecker, ie the instrument panel icons including the "locked out" icon lit up and the radio was "locked". Also the fob worked to remotely lock and unlock the doors. I noticed the air bag icon was now lit up whereas previously it never appeared, either with the old original faulty bcm or the bcm I picked up at the wreckers. However I could not start the van so I tried a procedure of turning the ignition key on and off three times which was supposed to remove the "locked out " icon and this should allow me to start the van. Much to my delight it was successful!!
A "quick scan" now produces the following codes
Bcm: C0278 - brake pedal pos'n sensor not calibrated
C0283 - brake pedal pos'n sensor circuit low
Supp Inflation restraint: B1001 - option config error
My radio is still locked and some instrument panel lights do not work. Hopefully having the bcm programmed will solve these issues plus the airbag icon. The main thing is that I can now drive the van and will not have to tow it to program the bcm.
PS Does anyone have any idea why the number of codes is sky high (up to 70 or so for the ecm), even for my G5 which is working just fine and shows no code faults when I choose the report option after a quick scan.
.
Last edited by SnowMan01; 12-16-2019 at 10:05 PM.
12-18-2019, 06:18 PM
#25
I can only hazard some guesswork - which I've already done too much of in this thread. Perhaps those are stored codes from the past malfunctions as opposed to active codes indicating current issues, and for some reason they just don't clear.
FWIW, our 99 Montana would throw the airbag light because of B1001 intermittently. We never did anything about it and it didn't amount to anything.
I think programming will take care of those brake sensor codes and you should be back on the road and good to go!
FWIW, our 99 Montana would throw the airbag light because of B1001 intermittently. We never did anything about it and it didn't amount to anything.
I think programming will take care of those brake sensor codes and you should be back on the road and good to go!
12-18-2019, 08:33 PM
#27
RevGTO That is the conclusion I was coming to on my own about those 100 or so codes that would not erase. These codes would always show up when I did an individual module scan, however they were not there when I hit the "report" key after doing what is called a "quick" scan on my scanner. After installing the new refurbished bcm my first quick scan reported a total of 11 fault codes in the following 4 modules, the ecm, bcm, ebcm, and the suppl inflatable mod. I was able to erase 6 of those (one comes back intermittently - B1001) but when I checked for all the other fault codes all 100 or so were still there! I cannot find a way to erase them! I think this scanner keeps them in memory for some reason. Like I have already said I have a Pontiac G5 so I thought I would use the scanner on it to see what would happen. The G5 has run like a charm every since I bought it new in 2009. The scanner showed almost 100 fault codes for it as well when I ran individual module scans. When I used the quick scan option and hit the report key there were no fault codes listed. So I think you are right about how this scanner handles fault codes . BTW the scanner is a Foxwell nt530. The user manual is useless in describing how the scanner handles all these historical fault codes or how to use the scanner as a reprogramming tool even though the website makes a statement indicating that it has that capability. I have been trying for over a week now to get some help with this but I am getting nowhere. Thanks for your input.
12-18-2019, 09:05 PM
#28
GMTECH4
Are you saying I should be able to reprogram a bcm I took out of another vehicle, ie the one I picked up at the wreckers? I have been told by two dealers in my area that this is impossible. If that is the case it is good news especially if my scanner will allow me to do a theft relearn. Do you know if the theft relearn would be done on the replacement bcm or another module? I think in all my confusion with my learning curve for this problem I saw somewhere that the radio has theft protection on it too. Would I have to relearn that too.
One of my ecm codes is p0315- crankshaft position (CKP) system variation not learned. I've done some research on this and I found a procedure which does not require a scanner. It describes taking the vehicle out on the road and doing a series of 5 cycles of taking the vehicle up to a speed of 55 mph and then decelerate down to 45 mph. Are you familiar with such a procedure or is this a bunch of hogwash? It states it is very important to have the vehicle at a high operating temperature in order for this procedure.
BTW I am located in Toronto. Trying to work around the cold here today to do more scans in a very cold vehicle. Temp right now is minus 12 degrees Celsius ( 10 degrees F).
Thanks in advance for any help you can give me.
Are you saying I should be able to reprogram a bcm I took out of another vehicle, ie the one I picked up at the wreckers? I have been told by two dealers in my area that this is impossible. If that is the case it is good news especially if my scanner will allow me to do a theft relearn. Do you know if the theft relearn would be done on the replacement bcm or another module? I think in all my confusion with my learning curve for this problem I saw somewhere that the radio has theft protection on it too. Would I have to relearn that too.
One of my ecm codes is p0315- crankshaft position (CKP) system variation not learned. I've done some research on this and I found a procedure which does not require a scanner. It describes taking the vehicle out on the road and doing a series of 5 cycles of taking the vehicle up to a speed of 55 mph and then decelerate down to 45 mph. Are you familiar with such a procedure or is this a bunch of hogwash? It states it is very important to have the vehicle at a high operating temperature in order for this procedure.
BTW I am located in Toronto. Trying to work around the cold here today to do more scans in a very cold vehicle. Temp right now is minus 12 degrees Celsius ( 10 degrees F).
Thanks in advance for any help you can give me.
12-19-2019, 07:15 AM
#29
I agree with RevGTO that the excess codes which show up in the individual modules are probably historical codes.
You should not have to do anything with the radio. GM did include more sophisticated theft protection in their double DIN radios than the TheftLoc in 4th generation f-bodies but it was self contained and not dependent on other modules. If your radio is working now then it will continue to work.
BTW, I just got back from a week in Toronto visiting family. I was lucky... it was only -4 for most of the week although the wind made it feel quite brisk.
You should not have to do anything with the radio. GM did include more sophisticated theft protection in their double DIN radios than the TheftLoc in 4th generation f-bodies but it was self contained and not dependent on other modules. If your radio is working now then it will continue to work.
BTW, I just got back from a week in Toronto visiting family. I was lucky... it was only -4 for most of the week although the wind made it feel quite brisk.
12-19-2019, 07:34 AM
#30
TECH Fanatic
The BCM in most (if not all) GM models is not reprogrammable. A new BCM is matched to the vehicle during initial installation and it cannot be reprogrammed after that. Fortunately for 4th generation f-bodies, the only programming is matching the resistor in the ignition key (it records the first key used after installation) so installing a used BCM is a simple matter of matching the key resistor pellet - there are only 14 possible values so it doesn't take long to find a match. Newer models were more sophisticated and actually matched to the VIN so transplanting a used one doesn't work.
Your analysis sounds correct. I can see how the dealer might think the action of removing and reinstalling might have jostled or reset something but it is very doubtful that it would happen that way every time you tried it. Besides, if I remember correctly, the BCM is easily accessible in your vehicle - under a seat - so there's not much to be jostled. If they're thinking a loose wire in the harness then why would it only be loose with the original BCM and not with the replacement? Unfortunately, I expect a new BCM will be quite expensive.
Your analysis sounds correct. I can see how the dealer might think the action of removing and reinstalling might have jostled or reset something but it is very doubtful that it would happen that way every time you tried it. Besides, if I remember correctly, the BCM is easily accessible in your vehicle - under a seat - so there's not much to be jostled. If they're thinking a loose wire in the harness then why would it only be loose with the original BCM and not with the replacement? Unfortunately, I expect a new BCM will be quite expensive.
Last edited by TA_Freak; 12-19-2019 at 08:09 AM. Reason: Perfectionist.
12-19-2019, 08:02 AM
#31
My radio is not working. Also as I understand it I have a pk3 key. I used a relearn procedure for a pk3 I found on the internet, turning igntion key on and off 3 times for a total time 30 minutes. This procedure allowed me to start the van with the refurbished bcm. My key does not have a resistor.
12-19-2019, 11:27 AM
#32
TECH Apprentice
Yes the bcm u got from the junk yard should work. Your radio is locked do to vin mismatch in the bcm. This happens even with new bcms. Basically that bcm needs to be configured to your van. Your donor bcm needs to have same opitions as your van if not it still can be programmed but you will need access to sps programming. I can check tonight but i don't think you need sps programming to configure bcm . Maybe a good scanner. Some dealers would come out better saying i don't know instead of giving people bad info and trying to them sell parts. People bring stuff like this in all the time at our dealership.
Last edited by GMTECH4; 12-19-2019 at 11:32 AM.
12-19-2019, 11:31 AM
#33
Whoppee!!! I finally was able to remove my engine light and airbag icons with the help of my scanner. Like I stated earlier on, I am very new to all this module stuff on vehicles so I am on a steep learning curve. Anyway my scanner has a special functions option which helped me clear those icons. I am sure you guys know all this stuff but I am a complete rookie at it. I had a p0315 dtc which read "crankshaft position (CPK) system variation not learned". The special functions option for the ecm allowed me to access this learn procedure so I gave it a try even though I wasn't sure what I was doing. And viola!! The engine light went out. I was also able to do the same with the airbag icon. I can now start and run the van with no troubling icons appearing! This is almost like magic. My radio still says it is locked and I can find no procedure to unlock it. I guess that will probably be cleared up when I have the bcm programmed tomorrow by the dealer. Any thoughts anyone? You guys have been a tremendous help to me and I want to give all of you a BIG THANK YOU!!!
12-19-2019, 11:37 AM
#34
TECH Apprentice
Whoppee!!! I finally was able to remove my engine light and airbag icons with the help of my scanner. Like I stated earlier on, I am very new to all this module stuff on vehicles so I am on a steep learning curve. Anyway my scanner has a special functions option which helped me clear those icons. I am sure you guys know all this stuff but I am a complete rookie at it. I had a p0315 dtc which read "crankshaft position (CPK) system variation not learned". The special functions option for the ecm allowed me to access this learn procedure so I gave it a try even though I wasn't sure what I was doing. And viola!! The engine light went out. I was also able to do the same with the airbag icon. I can now start and run the van with no troubling icons appearing! This is almost like magic. My radio still says it is locked and I can find no procedure to unlock it. I guess that will probably be cleared up when I have the bcm programmed tomorrow by the dealer. Any thoughts anyone? You guys have been a tremendous help to me and I want to give all of you a BIG THANK YOU!!!