So this was a fun one. As I mentioned in a previous story, my car died between San Antonio and Houston. Flicked the turn signal, engine shut off. Fun.

So, in case anyone is googling the symptoms:

• Turn signal, left or right, makes it happen
• Other user-accessible controls make it happen: parking brake, emergency brake, radio
• Waiting some time after turning the car on charges the battery enough that you can take it out of park
• Dash lights light up: traction control, ABS, service vehicle soon, I think.
• Sometimes airbags turn off, sometimes cruise control is off, sometimes cruise control is partially off (light is half on, and it kicks you off every ten miles or so).
• Engine shuts off, power shuts off, including power steering; the whole car turns off.
• Lights dim briefly, but don't turn all the way off

If these are your symptoms, you need to replace the ignition module. As I understand it, the issue is the following:

All the user accessible electronics, including the ignition module, are sitting on the same ground plane. When the ignition module is broken, there's not so much a short, as a low resistance contact, which causes the voltage to dip. The car needs to see a high voltage from the ignition module - nominally, 12V - to run. When you change the status of the electronics (turn signal, parking brake, etc), the switching causes the voltage to dip further; this causes the ignition module to put out significantly less than 12V, and the car thinks the ignition got turned off, so the whole car goes dark. Replacing the ignition module solves this problem.

I think the part is about $200, and the labor probably $50-200, depending where you get it fixed. For such a scary-feeling problem, a surprisingly cheap fix.

In the short term, after starting your car, let it idle for five minutes or so. This charges the battery to a higher voltage (often 13-14v); the ignition module puts out VCC (that is, the positive supply voltage, which is the positive battery voltage, not a regulated 12V), and the dips aren't brutal enough to push the voltage below the ON threshold. That extra volt or two will save you. In addition, as long as you drive without using the signals, you should be ok. Unplug any power-hungry devices (GPS probably OK, inverter probably not). Radio is fine, but again, don't fiddle with it until the car's been running for a while.