Bizarre electrical behavior in 2003 Mini

I’m experiencing strange, erratic electrical systems behavior in cold weather. When the car is started in ambient temps below 40 degrees F, headlights come on unswitched, like daytime running lights, although the car has never been programmed to display daytime running lights. Most other systems controlled by switches in the cabin–heater fan, windows, locks, turn signals, windshield wipers, dashboard lights–do not function regardless of switch position. Duration of the problem is dependent on ambient temperature. At 35 degrees it typically lasts about 40 seconds and functions are restored more or less simultaneously. In the teens or lower, it can go 15 minutes or longer and the switches may come back in a slow sequence. Not affected: radio, seat heaters. Do I need a priest to perform an exorcism on this car? Or is it just about British electrical engineering?

I had problems very similar to this with my POS Volvo, and the cause was a bad ground connection or two inside the dashboard. As soon as the engine reached full operating temperature and there was adequate heat inside the cabin, it was like throwing a switch when suddenly everything began operating properly–or at least as well as anything on a Volvo can operate.

I can tell you from experience that Swedish electrical engineering is no better than the electrical engineering in England or in Germany.

A bad ground/poor connection could do it, especially if it’s near the Body Controller Module. I don’t know what all the BCM controls on your car, but I’d suspect a poor connection to the BCM or a flaky BCM, with all the separate systems that are involved. On a lot of newer cars the switches, including the headlight switch, don’t directly control anything–they send a signal to the BCM, which acts on the inputs and energizes relays for the headlights, etc. If it’s flaking out, you can get all sorts of strange behavior.

You may also have an alternator that’s putting out a lot of AC ripple into the car’s electrical system. When you first start your car when it’s ice cold, the alternator is putting out a lot of current to recharge the battery. If it’s malfunctioning, this is when it would be wreaking the most havoc on your car’s electrical system and possibly confusing the BCM or interrupting communication between different modules. I think this would usually turn the check engine light on, but not in every situation.

It would also be a good idea to make sure your battery connections are clean and tight. Poor connections at the battery can cause all sorts of weird effects on modern computerized vehicles.

I suspect the head light problem could be due to a faulty light switch. Proper testing should be done to prove it before replacing it. The other issues could be due to a bad ignition switch. Check the dash fuses for power with the switch in the ON position. If there is no power to some of the fuses then the switch needs to be checked.

Thanks, guys. Going in the shop in a couple days. I’ll let you know how this sorts out.

It does sound like a bad electrical connection somewhere, either ground or just one of the dashboard connectors. No harm done to have the battery and alternator tested too.

Coincidentally, this 'ol Corolla of mine has developed a similar “ghost in the electricals” problem. The dashboard illumination of the heater controls doesn’t turn on with the headlights like it used to. But I discovered I could switch the heater fan on, and then the light would turn on, presto-chango. So that’s my work-around solution, no crawling under the dashboard for me. Maybe the OP can switch some switches, do an experiment, find a way to get things to work in a similar work-a-round fashion.