I am having issues with windows and door locks not working, so I ran the Mode1 LAN diagnostics an got a boat load of codes.

I got "Data Line B No response" to every LCU, and got "Data Line A No Response" for LCU 02B, LCU 03, and LCU 04. (a total of 14 codes). With Data Line B completely dead, I suspected the BCU was bad, so I swapped the puppy out...didn't help a bit.

Data B is toast...fine, so I tried to diagnose the problem with Data A.
So, I don't understand how Data A to LCU 02B is dead, but LCU02A is working fine They are both in the right front door.

There doesn't seem to be a common point in the wiring that would lead to a failure of these three LCUs.

Is it possible that one of the LCUs has failed and is throwing garbage on the Data line that is interfering with communication to the other LCUs?

Any help is greatly appreciated.
















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Anyone got any ideas on the best way to diagnose this??

The LCU in the drivers front door sends signals to the LCU's in the other 3 doors. I suspect that it has a melted solder joint, probably on the ground circuit. Take it apart and look at it for anything obvious. If you're good at soldering trace the ground circuit from the connector, melt the solder and reapply. It's a pricey part so you want to try and repair it yourself before buying new from the stealership if they're even still available.