Low battery - now command/radio wont power on...

[majoreyeswater]

Ignition was left on whilst doing some work, which drained the battery quite a lot - the car did manage to start, but albeit was sluggish and slow to turn over.

Problem now, is that the command/radio unit will not power on, infact no lights are on the unit, except the heated seat and parking buttons.

Im getting code B210A84 - power supply in system is low

How do i reset this module?!

 

[markjay]

My guess is that either the battery has not yet fully charged, of the deep discharge killed it off and it will never recharge sufficiently.

Try taking the car for a long motorway drive, or use a trickle charge (e.g. CTEK) to charge it overnight. You want the battery to show 12.6v-12.7v with the engine off.

If this doesn't work, then you'll need to replace the battery.

The alternator should produce ~14.5v, but if the battery is damaged and has a short circuit in one or more cells, it will affect the alternator output.

 

[majoreyeswater]

Well, a week after the issue and still nothing.

I did however checkthe battery voltage first thing before i drove it, am getting 12.4v - does that sound okay?

Im clueless, but my thoughts are pointing to a module somewhere that needs resetting?

 

[markjay]

I did however checkthe battery voltage first thing before i drove it, am getting 12.4v - does that sound okay?

The battery is a little weak (it should ideally be 12.6-12.7v), but this voltage shouldn't in itself stop COMAND from turning on.