Article by: Johan
Article applies to: all e32 and e34 models (some variations may exist).
The left side:
Picture taken from a 1990 750i.
The servotronic control module controls the amount of power assisted steering based on the road speed. The faster you go the stiffer the steering will become.
The later model years seemed to have a more complex servotronic control box:
The “sensor lock” module which seems to be on the 750 only controls the compressor cut off when one of many conditions is reached (like pressure too high/low, evap frozen . . .)
AUC control unit:
If you have an aircon system with AUC you will also find the AUC control module over here.
The AUC is an option where the outside air is monitored for hazardous concentration of certain gases such as CO and NOx.
If the concentration of the gasses is too high the climate control system automatically switches to re-circulation mode.
The right side:
Behind the speaker cover in the right side foot well you will find:
EGS control module
The EGS module controls the automatic transmission.
Note: It is possible to upgrade (swap out) the main EPROM control chip in this automatic control unit for a performance chip – such as from Dinan. This has the effect of making the shift points more aggressive and will feel “sportier”. It may also have a net benefit on fuel economy (depends on the condition of the vehicle). See picture below. ~ Mike Oswald
Ruckschalt sperre – which is an extra control box for the automatic gearbox
Below is the full list of modules: (not limited to the foot wells)
Cruise control module
Standlufting/standhezung relay box
IR remote locking control
Park distance control
EDC control unit
Memory seat control module
Relay type modules:
crash alarm geber
ABS overvoltage relay