bcm functions/ Bad BCM ?

[Tedcz]

Hello – I think I might have a bad BCM- The car will start then will turn off after a second.None of my key fobs will work-wont lock or unlock anything.They wont resync,I know the batteries are good. The dash/instrument cluster isn’t working properly either. The lights and gauges are not displaying correctly. Im guessing this happened when a portable air pump using the cig socket it had a short across the 2 wires, it blew the cig socket fuse as it should,but I think this happened right about this time. Im not sure though looking at the electrical diagrams.The windows and door locks work manually. Any help would be appreciated. What functions does the BCM do as compared to the comfort control module. If either are replaced do I need to have them reprogrammed? Trying to avoid taking to dealership.I dont have vagcom. One other thing if i order a used BCM does anyone think the symptom would change such as the dash working at least, or car starting

[PhireSideZA]

I'd start by checking all the fuses on the side of the dashboard and the relays under the ECM.

I was chasing a bad BCM/CCM a while back that turned out to be a bad positive battery cable. So, maybe also check the terminals and that the wires didn't maybe get hot and cause issues.

From what I have gathered, the BCM controls features 'outside' the car like indicators, headlights, tail lights, etc. whereas the CCM or Comfort Module are 'interior' features like the sunroof, electric windows, cabin lights, that sort of thing. If you replace either module, you'd need to code them the same as your old module. OBDEleven can also do the coding, but it's a ZAR2000 dongle and a ZAR400 yearly subscription to have access to the coding ability. Sorry, I'm not sure what it would be in US$ but it's probably about half the price of a VCDS cable.

I hope my explanation makes sense. Good luck!

[Tedcz]

Fuses have all been checked,only one that was bad was for the cig lighter caused by air pump.There were 2 fuses under the ECU that had 3volts while turning the key to on position,but dont know if that was normal.I havent looked to see if theres any water in the comfort controll module area but all interior windows locks work normally. What controls the instrument panel and fob key functions? When turning on key barely any lights come on the panel / dosnt look normal, the gas gauge and tach not working either. One thing I also noticed was when taking battery cables off - the radio SAFE condition came on, which has never happened since Ive owned the car. The car cranks and starts then turns off. Anymore ideas to look at before taking to dealer.I looked at CCM under carpet -no sign of moisture or water down there.

[Tedcz]

Update-yesterday the instrument lights came on like nothing happened,unbelievable. The car started like nothing was ever wrong. I was able to resync the Fob keys and they are working again. It wouldnt start all week. I have no idea,if something got wet then dried. Had 10 inches of snow earlier in week. Scary not knowing what caused this. Found no water where ECU sits or BCM CCM areas either. if this happened to someone else please let me know if you found anything.Thanks

[Tedcz]

Well im back to square one. The instrument cluster is now not displaying lights when turning on to start. Car cranks starts then turns off. The Fob keys are still opening and closing doors. It started all week before today.

[Shifted_04]

Did you ever figure this out. We just got heavy rain here and now I have this same issue. Pulled U0155 IPC and U0104 Cruise Control Module. Checked ECM box for water intrusion and its dry.

[TUBBWASHERE]

chasing the same problem rn!

[LightweightC3]

Well im back to square one. The instrument cluster is now not displaying lights when turning on to start. Car cranks starts then turns off. The Fob keys are still opening and closing doors. It started all week before today.

I’m going through the same exactly symptoms that you described, did you resolved the problem, did you have to change the body control module ? Any help would mean a lot… I have 3 months chasing this problem with no good results.

[rollerton]

BCM will cause a lot more oddball and severe problems than just cluster issues. It sort of sounds like your cluster alone is just intermittently failing / losing comm. The real first step is to check fuses related to the part that's causing problems, check connections power supply and grounds, and scan with VCDS.
If you can't connect to the instruments module over OBD, it could be worth grabbing / borrowing a spare cluster to swap and see if it reliably powers up and functions. If it does NOT, then you've mostly ruled out the cluster as your failure- because the problem is still there. If it does power up reliably, you can start digging deeper into electronics based on errors in other modules, or whatever the troubleshooting procedure is for upstream electonics.

[q_dubz]

i have a similar issue as of this morning