Hello, yet another thread on never ending red battery light problems. The error code is faulty power relay (the one next to the battery mgmt module). The light has been on for a long time with many attempts to fix it, none of them has made any difference, in summary:
- the relay has been replaced twice (in case first replacement was faulty)
- both batteries have been replaced
- battery mgmt module has been replaced
- all fuses checked, including passenger footwell, all cable joints on fuses/devices/batteries etc removed/cleaned/reinstalled
- voltages measured, not pointing to obvious alternator etc problems, etc

Clearing the error removes the error light, but it always comes back eventually.

The only indicator now which is pointing somewhere is that the instrument cluster could be causing a voltage drop recognized by the BMS and giving the error (at least according to my mechanic, I've given up on trying to fix it).

Has anyone experienced the Instrument Cluster causing the dreaded red battery light?

 

What is your mechanic using to diagnose this issue? Sounds like you have spent a lot of money and got nowhere?

Does he have STAR SDS or Xentry?

 

Did checking the fuses in the footwell just look for voltage on both sides, or a resistance? It will get voltage on both sides of the batteries are hooked up and the fuse is bad. If the fusevis bad I believe it won’t charge the front battery though. Sure would be nice to do away with the dual battery nonsense in these cars.

 

Using STAR SDS/Xentry with programming capabilities, Vediamo, and several other professional tools able to pretty much read/write/reprogram everything.

All fuses were removed and checked out of car.

So interesting if the instrument cluster could be impacting the load/confusing BMS as the mechanic thinks, or it could also be something very simple we have overlooked.

 

For some reason, the B1828 code (assuming that's the one you are getting) is a faulty K57 relay OR no circuit 61. Think of circuit 61 as what keeps the alternator 'idiot light' from turning on. It is the diagnostic wire from the alternator and is read by the front passenger SAM. It is possible that you either have an intermittent problem with the alternator or an error reading it (bad wiring connections, bad SAM).

 

Thanks @MikeJ65, sounds plausible, I've passed it to my mechanic and he says he has already tested that, so mystery continues...