Body Control Module Random Freakout
Thread Starter
Instructor
Joined: May 2008
Posts: 239
Likes: 4
Body Control Module Random Freakout
2008 Base Coupe, M6, 140k miles, bought new.
last few thousand miles I get a random failure which points to the BCM. Usually after the car has been driven some miles and is fully warmed up I will get a cascading failure which usually starts with the cruise control kicking out and an active handling DIC. The AC compressor will drop off line, and then the dash will completely light up, the DIC cycles through all the chassis warnings, and then the needles on the cluster will drop to zero (except speedo, tach and volts). Car continues to run fine and will stop and start. Sometimes a restart will clear some or all of the malfunction. Sometime the condition hangs around for several drive cycles, and sometimes it just goes away.
i have performed the following:
Cleaned all grounds in the car
Cleaned the battery terminals
checked condition and voltage of battery
Removed, inspected and cleaned the BCM main connectors
Anybody have experience with this? If the BCM is failing, anybody knows what the failure mode is? I'm not about to shotgun parts at this issue, I'd like to know what's going on.
My thanks
last few thousand miles I get a random failure which points to the BCM. Usually after the car has been driven some miles and is fully warmed up I will get a cascading failure which usually starts with the cruise control kicking out and an active handling DIC. The AC compressor will drop off line, and then the dash will completely light up, the DIC cycles through all the chassis warnings, and then the needles on the cluster will drop to zero (except speedo, tach and volts). Car continues to run fine and will stop and start. Sometimes a restart will clear some or all of the malfunction. Sometime the condition hangs around for several drive cycles, and sometimes it just goes away.
i have performed the following:
Cleaned all grounds in the car
Cleaned the battery terminals
checked condition and voltage of battery
Removed, inspected and cleaned the BCM main connectors
Anybody have experience with this? If the BCM is failing, anybody knows what the failure mode is? I'm not about to shotgun parts at this issue, I'd like to know what's going on.
My thanks
Thread Starter
Instructor
Joined: May 2008
Posts: 239
Likes: 4
I guess I didnt expect a flood or responses, but nobody has seen this failure? I guess thats good for the product, bad for me.
Drove to work yesterday and the only failure was the "service active handling" DIC and warning lamp. This seems to be the leading condition in all prior failures. In other words, the active handling DIC always starts it off.
The drive home was completely normal. No lights, no fails. Wonder how long before it comes back...
Drove to work yesterday and the only failure was the "service active handling" DIC and warning lamp. This seems to be the leading condition in all prior failures. In other words, the active handling DIC always starts it off.
The drive home was completely normal. No lights, no fails. Wonder how long before it comes back...
Race Director
Joined: Dec 2013
Posts: 12,502
Likes: 3,629
Step one, take a photo of the fuses/relays/diodes in the engine fuse box so you know how they go back in, then pull the Upper fuse box to pull the fuses/relays/diodes, douche the hell out of it with Electrical spray cleaner, light it up with silicone spray to get the inside of it semi corrosion protected without having to pull it covers, and do the same for the lower blocks as well.
Once you get that done, then same for all the BCM connectors (including the red connector), then all the ECM connectors, and finish off with the EBCM connectors.
From here, pull the battery, and on the fender wall at the side of the battery, have a C186 and C184 connector that need to be cleaned as well.
3 and 4, but may want to check all the connectors while you are there.
Last one, get under the car, and check the alternator to battery cable connections at the starter solenoid. Once you are sure that its clean and tight, right above the starter is the ground cable to the engine, that you want to clean and make sure it tight as well.
Bluntly, GM did not use a single drop of any electronic protector on any of the connectors, and most of the electrical problems with the C6, is due to corrosion on the connector pins/sockets/cable ends.
Once you get that done, then same for all the BCM connectors (including the red connector), then all the ECM connectors, and finish off with the EBCM connectors.
From here, pull the battery, and on the fender wall at the side of the battery, have a C186 and C184 connector that need to be cleaned as well.
3 and 4, but may want to check all the connectors while you are there.
Last one, get under the car, and check the alternator to battery cable connections at the starter solenoid. Once you are sure that its clean and tight, right above the starter is the ground cable to the engine, that you want to clean and make sure it tight as well.
Bluntly, GM did not use a single drop of any electronic protector on any of the connectors, and most of the electrical problems with the C6, is due to corrosion on the connector pins/sockets/cable ends.
Thread Starter
Instructor
Joined: May 2008
Posts: 239
Likes: 4
Did the BCM connectors and the C184/186 first, will get to the rest soon. Did not detect any corrosion, but certainly dusty and DRY. I can see how this lack of corrosion protection can bite you over the years. I feel better now, and so far, no warning lights.
