2006 X5 3.0i keeps running with key off

[andrewwynn]

it will turn out to be one of these two things: .

1) shorted wires in a bundle: it's intermittent because it's signal level amperage so not enough to blow fuses, melt wires or weld together (to stay shorted) or
2) some device that shares common pins has an internal fault that causes back feeding of power onto an input line. Intermittent because it's low level signal but the fault trips some version of a "holding relay".

I would look for any non mission critical devices and unplug them. Half at a time if possible; divide and conquer.

[Clavurion]

Originally Posted by andrewwynn

it will turn out to be one of these two things: .

1) shorted wires in a bundle: it's intermittent because it's signal level amperage so not enough to blow fuses, melt wires or weld together (to stay shorted) or
2) some device that shares common pins has an internal fault that causes back feeding of power onto an input line. Intermittent because it's low level signal but the fault trips some version of a "holding relay".

I would look for any non mission critical devices and unplug them. Half at a time if possible; divide and conquer.

I was also thinking those modules which have both continuous (Terminal 30) and switched (Terminal 15) supply. But still something doesn't add up. When this happens everything seems to work normally so there is quite high amperage needed. Both Terminal R and Terminal 15 rails need to be backfired and as measured they both are and have battery voltage so the source can't be any thin wire or low amp fuse. And this doesn't explain why at the same time those supply lines for ignition switch drop voltage even though they are connected to front fuse box with 4 mm2 wire and 50A fuse which just happens to look like it's been hot by the colour change of the connection on fuse box.