BCM replacement

[Noir]

So been having issues with an odd battery drain, sometimes it will last for a week without running and start right up. Other times, it's dead the next day. Took it to a place that ran a parasitic drain test, believe that's the name they called it and they came back saying the bcm is showing all these memory faults and holds of power leakage. Trying to find a replacement, but it is a 2005 lr3 hse. Question, is this a module for module swap or is it tied to the vin of the vehicle? Suggestions on places to find one? Someone with more knowledge may know this, but is this tied to hdc faults, which usually leads to suspension fault? Have an engine system fault, and some other oddities like open circuits to mirror and speakers, which all work fine. Trying to understand what this ties to and what it will and won't fix.

Thanks.

This is the code the shop said tells them BCM - B1B85-49

Not sure if anyone wants to see, but here is what I get for a list of codes with gap tool. Some come and go and will clear out and then come back months later, so not sure if legit errors or symptom of something else.

Audio Amplifier - it's a 21 year old vehicle, sounds decent, subwoofer may be shot or close to it, but everything else works, sound out of every speaker.

• B1A01-13 (10) Speaker 1 circuit - General electrical failure - circuit open
  ( on 20-03-2032 03:50:49 at 0 km )
• B1A02-13 (10) Speaker 2 circuit - General electrical failure - circuit open
  ( on 20-03-2032 03:50:49 at 0 km )
• B1A09-13 (10) Speaker 9 circuit - General electrical failure - circuit open
  ( on 20-03-2032 03:50:49 at 0 km )
• B1A10-13 (10) Speaker 10 circuit - General electrical failure - circuit open
  ( on 20-03-2032 03:50:49 at 0 km )
• B1A03-13 (10) Speaker 3 circuit - General electrical failure - circuit open
  ( on 20-03-2032 03:50:49 at 0 km )
• B1A04-13 (10) Speaker 4 circuit - General electrical failure - circuit open
  ( on 20-03-2032 03:50:49 at 0 km )
• B1A07-13 (10) Speaker 7 circuit - General electrical failure - circuit open
  ( on 20-03-2032 03:50:49 at 0 km )
• B1A08-13 (10) Speaker 8 circuit - General electrical failure - circuit open
  ( on 20-03-2032 03:50:49 at 0 km )
• B1A11-13 (10) Speaker 11 circuit - General electrical failure - circuit open
  ( on 20-03-2032 03:50:49 at 0 km )
• B1A12-13 (10) Speaker 12 circuit - General electrical failure - circuit open
  ( on 20-03-2032 03:50:49 at 0 km )
• B1A05-13 (10) Speaker 5 circuit - General electrical failure - circuit open
  ( on 20-03-2032 03:50:49 at 0 km )
• B1A06-13 (10) Speaker 6 circuit - General electrical failure - circuit open
  ( on 20-03-2032 03:50:49 at 0 km )

Instrument Pack - this is a cluster**** no idea if any of it are true errors.

• U0128-87 (27) Lost communication with parking brake control module - Bus signal/message failure - missing a message
• B1A00-46 (50) Control module - System internal failure - calibration/parameter memory failure
• B1A75-92 (50) Fuel sender 1 circuit - Component failure - performance or incorrect operation
• B1A76-92 (50) Fuel sender 2 circuit - Component failure - performance or incorrect operation
• B1A80-64 (50) Oil pressure circuit - Algorithm based failure - signal plausibility failure
• B1A81-64 (50) Internal trip switch circuit - Algorithm based failure - signal plausibility failure
• B1A82-64 (50) External trip switch circuit - Algorithm based failure - signal plausibility failure
• B1A84-46 (50) Vehicle configuration data - System internal failure - calibration/parameter memory failure
• B1A86-64 (50) Ignition status - Algorithm based failure - signal plausibility failure
• B1A87-68 (50) Battery disconnection/electronic control unit reset - Algorithm based failure - event information
• B1A00-17 (50) Control module - General electrical failure - circuit voltage above threshold
• B1A00-16 (50) Control module - General electrical failure - circuit voltage below threshold
• B1A88-49 (50) System timer - System internal failure - internal electronic failure
• B1A00-4B (50) Control module - System internal failure - over temperature
• B1A00-48 (50) Control module - System internal failure - supervision software failure

Steering Angle - have fixed this in gap tool and randomly comes back.

• U1A14-49 (50) CAN initialisation failure - System internal failure - internal electronic failure
• C0051-64 (50) Steering wheel position sensor - Algorithm based failure - signal plausibility failure
• U3002-62 (50) Vehicle identification number - Algorithm based failure - signal compare failure

Terrain Response - switches terrains fine, throws no errors, so again unsure.

• U1A14-49 (50) CAN initialisation failure - System internal failure - internal electronic failure
• C1A02-94 (50) Rotary encoder stuck in the intermediate position - Component failure - unexpected operation
• C1A01-96 (50) LED circuit - Component failure - internal failure

Transfer Case - from the different shops that have looked at the vehicle, nothing negative about the transmission, so not sure on these.

• P0903-00 (50) Clutch actuator - circuit high
• P0902-00 (50) Clutch actuator - circuit low
• P0900-00 (50) Clutch actuator - circuit/open
• P173F-00 (50) Ignition key lock solenoid - circuit high
• U0128-87 (2F) Lost communication with parking brake control module - Bus signal/message failure - missing a message
  ( on 07-06-2026 14:18:50 at 359374 km )

Transmission - never use the epb, so low on list of concerns.

• U0128-87 (2F) Lost communication with parking brake control module - Bus signal/message failure - missing a message
  ( on 07-06-2026 14:18:50 at 359374 km )

Ventilation - all odd as heat and cooling work perfectly, never had a single issue

• B1A73-18 (50) Left seat heater - General electrical failure - circuit current below threshold
• B1A74-18 (50) Right seat heater - General electrical failure - circuit current below threshold
• B1B74-00 (50) Front foot-defrost mode stepper actuator
• B1B74-49 (50) Front foot-defrost mode stepper actuator - System internal failure - internal electronic failure
• B1B75-00 (50) Front foot-face mode stepper actuator
• B1B75-49 (50) Front foot-face mode stepper actuator - System internal failure - internal electronic failure
• B1B76-00 (50) Front left air blend stepper actuator
• B1B76-49 (50) Front left air blend stepper actuator - System internal failure - internal electronic failure
• B1B77-00 (50) Front right air blend stepper actuator
• B1B77-49 (50) Front right air blend stepper actuator - System internal failure - internal electronic failure
• B1B82-00 (50) Rear air distribution stepper actuator
• B1B82-49 (50) Rear air distribution stepper actuator - System internal failure - internal electronic failure
• B1B83-00 (50) Rear air blend stepper actuator
• B1B83-49 (50) Rear air blend stepper actuator - System internal failure - internal electronic failure
• U0073-88 (50) Control module communication bus off - Bus signal/message failure - bus is off
• U0300-55 (50) Internal control module software incompatibility - System programming failure - is not configured

 

[douglastic]

Didn't see these details in your post:

did you test the battery? age? might need a new one.
did you test alternator?
did you clear all codes manually before seeing which return?

"lost communication" and "circuit voltage/current below threshold" are usually due to low battery,
and not real problems on their own

these vehicles really require fresh/full voltage to be happy

 

[Noir]

@douglastic Yes, battery is only a few months old, been replaced twice. Yep, alternator good as well.

Cleared them, but many don't clear, they come back, the ones listed all came back after clearing.