C400 means connector 400. It's location would be shown in the service manual.
Disconnecting various items and connectors is part of isolating and locating short circuits. It sounds like they only did half the job. By unplugging C400 and finding the fuses still blow, they determined the problem is before that connector. They narrowed down the list of suspect areas, then stopped. Depending on where that connector is in the car, for that many circuits to be affected at once, look for chewed up trailer connector wires, something slid around in the trunk and crushed a bunch of wires in a harness, or a wiring harness fell down onto hot exhaust parts.
Thursday, September 8th, 2011 AT 6:13 AM