In Reply to: 6 disk CD changer question posted by Jeff on July 08, 2000 at 11:21:08:
You have the 540, which has, as standard equipment, the "high" version of the instrument cluster (text read-out and expanded OBM & Check Control)
The 6 cylinder cars are normally equipped with the "base" cluster and OBM & Check Module.
The High version cluster has it's own bus system - the I Bus (instrument bus) which is connected to the following:
- MID or Monitor display
- Compact disk changer
- Audio amplifier
- radio (head unit)
- Light Control & Check module
- Multi-function steering wheel
The I bus isolates the digital signals between these modules from the rest of the car. Any interface to the car bus (K Bus) is through the instrument cluster.
If you have the "Base" cluster (528) there is no I bus, in which case all those units communicate directly on the K bus.
There is no "advantage/disadvantage" of having one bus verses the other. It is just that the "high" version of the cluster, OBM, CC provides many more functions that it is better to have it's own bus for communications.
One downside of just using the common K bus might be a greater possibility of interference of signals on the common bus - and "perhaps" that is why we see occasional electronic glitches. Just uessing here - and yes the 540 also has it's share of odd-ball glitches
(like on some occasions when I turn off the ignition and then immediately turn off the parking lights the phone comes to life and says "Name Please". It has yet to say "Don't do that Dave" (remember Hal)