when you get it Don. It has two modes - CANBus and normal. It'll come set to one of those and in order to change it, you plug it in and touch the +ve and -ve leads together briefly.
Oh and....the lead with the plug for the BMW accessory socket is an accessory. You need to make sure you get one of those.
I defer to others' far superior knowledge of all things electrical, but the instructions which come with the dual charger suggest that the process of changing requires a little more time than a quick touch of the clips or (as I was told to do by Nippy Norman's) short out the terminals on the CanBus plug with a paper clip.
Here's what the instructions say:
1. Disconnect the charger from the AC supply
2. Attach the battery clip set to the charger and connect the negative clip directly to the positive clip
3. Re-connect the charger to the AC supply
4. Observe the following LED indications:
LEDs #3,4,5,6 and 7 flash 12 times during selection of the alternative program (5x slow, 5x fast, 2x slow)
After the program change the following indications can be observed (with battery clips still connected together):
- changed from CAN-bus to STANDARD: only the POWER LED#1 remains on
- changed from STANDARD to CAN-bus: LED #3 and LED #4 flash together at regular intervals with LED #8 immediately following