Article by: Johan
Applies to: all e32 and e34 models.
Under the rear seat you will find a bunch of modules on the left side. The modules you will find are dependent on the options your car has.
You can expect to find the:
- zentral karosserie electronics (ZKE) or central body electronics
- OBC relay or alarm module (DWA)
- park distance control unit (PDC)
- IR-remote locking control unit
- rear seat electrical headrest control unit, and
- wiper pressure control unit.
The ZKE: This system consists of two modules.
The relay module (RM) and the general module (GM). The relay module consists of a bunch of relays that control high current systems like the electrical window motors . . . etc.
This system controls the central locking, the windshield wash and wipe system, the headlight wash system (via headlight cleaning module), the electrical windows and sunroof and the interior lighting.
The ZKE also uses a crash sensor also mounted under the rear seat to detect crashes. In case of a crash the ZKE will unlock the doors and turn on the interior lighting.
The inside of my >92 general module. As you can see it only has one PCB. Older types have two PCBs installed.
An added bonus of the the >92 control module that came in my 1987 735i is that all four windows have one touch down. Happy happy me 🙂
Some E34s come with a “light” version of the RM lacking a couple of relays. So watch out when you replace the module!
Park distance control. This is the brain of the PDC audible parking aid.
IR-locking system The control module for the IR keyless entry system.
Electrical rear headrests These seem to be standard on all iL models and a very rare option on the short wheelbase models.
OBC Relays or DWA If your car came without a factory alarm system you will have a OBC relay. This relays power the OBC so without it your OBC won’t work.
Always check this fuse when the OBC is dead and replacing the lights doesn’t work. If you have a factory alarm system the OBC relays’ function are replaced by the alarm control unit.
The OBC’s code functions are automatically invoked by the DWA system.
There are several different systems: DWA II, DWA III and DWA IV.
Below is the OBC horn module:
The OBC relay. Inside this thing has just a relay.
The DWA II module.
Wiper pressure control. The e32 also has a system where the pressure of the wiper on the driver side is increased as the road speed increases.
This module is called “Anpress druck reglung”.
Other modules: On cars with EDC the control unit is located on the right side near the battery.
That should cover all the modules under the backseat.