The E39 M5 is a complicated car. In order to keep the wiring harness from outweighing a Yugo, it’s even got an in-car network. The ibus (iBus? i-bus?) lets the CD changer, amp, navigation computer and other dense boxes of technology talk to the Light Check Module, the sunroof, the Seat Occupancy Recognition Unit, the Boot Lid Control Unit and the like with only three wires. With the help of a magic box from Germany and a helpful program called NavCoder from New Zealand (I think), you can tap into the ibus and eavesdrop. You can even re-code various components or query them as to their model number, date of manufacture and any stored error codes. In my case, the headlights in the car have LED lights in the Angel Eyes - the rings around the headlights. The Light Check Module checks for low resistance in various bulbs and alerts the driver if a blown bulb (ie, low resistance) is detected. But the LEDs are low resistance, so every time I turned on the car I’d get the warning. Using NavCoder, I disabled the check on the Angel Eyes so the car is once again at peace. There’s also a problem with my radio, and it’s throwing an error code through the ibus. I’ll use that to diagnose what’s happening. Awesome.
Oh, and I also installed a set of Koni Sport shocks to replace the high mileage stock units. Big improvement. The car always felt both a little floaty and a little eager to blow through the suspension travel and punish the bumpstops. Not anymore. It took me 4.5 hours to get the rear shocks changed, as you have to disassemble the entire back half of the car. Step one, remove the rear interior lights…
