Might be interesting - if any are wrong, correct me.

Wally Plumley
928 Specialists

• ABS Control Unit - Drivers footwell, on the side, just above the hood release.
• Differential Lock Control ('90-up)- Combined w/ABS
• Bulb Control Unit - Passenger's parcel tray. Monitors the current flow to the small lamps, and warns if one is out.
• Fan Control Stage (S4-up) - Right front engine bay on front panel.
• Fan control Unit (S4-up) - Between passenger door & seat under removable cover.
• Oxygen sensor counter (early cars) - Between passenger door and seat under removable cover.
• Stereo Amplifier - Between pass seat and door under removable cover.
• Airbag Control Unit ('90-up) - In center console.
• Airbag Sensors - High on left & right kick panels.
• Alarm System Control Unit (thru '89) - Behind glove box
• Alarm System Control Box ('90-up) Under left seat. (To provide more room for the Airbag)
• Central Warning Control Unit - Under driver's footrest (that is <inside> the footrest).
• Cruise Control Unit - In center console. (little silver box)
• Cruise Control Actuator - In left fender.
• Central Electrical Panel - Under passenger footrest (floor).
• Fuse for Locks - Small in-lines, above/behind Central Power Panel.
• Fuse for Rear Hatch - Early cars, in-line under hatch carpet; late cars, # 26 in Central Power Panel, returns motor to start position
• LH Injection Control Unit - Outer box on Passenger kick panel.
• EZK Ignition Control Unit - Inner box on Passenger kick panel.
• Ignition Final Stage (S4-up) - Left front panel in engine compartment.
• Mirror Memory Control Unit (Late cars) - Drivers footwell.
• Seat Memory Control Unit (late cars) - Under seat.
• Tire Pressure Control Unit (PDK) - Above driver's kick panel.