The door locks on W463 trucks, unlike MB sedan/coupe/convertible models of the era, are electrically powered, rather than vacuum controlled. This results in a very enthusiastic, "zippy" actuation of the door locks, as opposed to the softer up-and-down motion of the vacuum powered locks in the regular MB passenger cars. The system is used is generally identical in W463 trucks produced from 1990 through 2001, and some of the system's components are even used up to the present day.
This post pertains to these early-generation G-wagens, produced from 1990 through approximately 2001.
For the G-wagen, there are three important elements to the system:
- The electric door lock control relay
- The driver's side "Master" electric door lock actuator
- The passenger/rear passenger/tailgate/fuel flap "Slave" electric actuators
Electric door lock control relay:
Driver's door master ("five-wire") electric actuator:
Passenger/rear slave ("two-wire") electric actuator:
G-wagen fuel flap slave electric actuator:
The system is controlled overall by the electric door lock relay, which is located in the truck's relay panel. For those so equipped, say after 1993 or so, this is somewhat integrated with the truck's alarm/immobilizer system (in the case of my early G-wagen, the IRCL DAS-2 system, and for other trucks its IRCL predecessors & successors). The relay controls the flow of electricity to the next major component in the system -- the driver's door master lock actuator.
The driver's door actuator has five wires, and it signals the other door lock actuators on the car to open or close. It serves as the "Master" for the rest of the system. Similarly to the sedans, when you push the driver's door lock button down or up, it locks or unlocks all of the actuators at the same time.
The remaining actuators in the three passenger doors (for long-wheelbase trucks) and rear tailgate are two-wire systems and serve as "Slaves" to the master actuator in the driver's door.
It is not uncommon for these actuators to go bad, and there can be several reasons for this. Sometimes it's faulty wiring, and sometimes it's a fault in the actuator itself due to age/use. The inside door panel must be removed to replace the actuator, but it's a relatively simple matter to do this, and is self-evident when an actuator goes bad. Generally, if a passenger door actuator goes bad, that door's lock will not go up or down, while the rest of the locks in the system act normally.
Here is a HOW-TO on replacement of a slave actuator (driver's door master actuator will be similar).
If a driver's door "Master" actuator goes bad, you will observe that none of the actuators go up or down, or they can act intermittently to lock and unlock.
If the control relay goes bad, generally also none of the actuators in the system (including the driver's door Master actuator) will go up or down. Often you will hear a distinct "click" at the driver's door actuator, or from the area where the relay is located.
Recently I had the control relay go bad in my 1995 G320.
Depending on the year of truck, the door lock control relay can be located either in the under-dash fuse+relay panel below the glove box on the passenger side (early trucks through about 1996-1997), or in the triangular relay compartment underhood on the passenger side just forward of the truck's firewall. If the latter, it is located UNDER the famed "K40" relay.
The door lock control relay is easily identified as it is a small, rectangular relay about the size of a pack of cigarettes, and it has the large word "kiekert" printed on its exterior, along with the MB part number 009 545 19 32. This relay is currently available through the normal MB parts discounters for around $145.
Views of the Kiekert relay, including disassembled:
IMG_7736.JPG IMG_7737.jpg IMG_7738.JPG IMG_7739.JPG
Quite often, these Kiekert relays fail in a very intermittent mode, and this is caused by one or two cracked solder joints. This seems to be a pretty consistent problem once these Kiekert relays reach a certain age.
The diagram below shows the location of the poor solder joints that can affect proper operation of the Kiekert relay. The second photo shows my actual Kiekert relay, and its faulty/cracked solder joint.
Cracked solder joint in my Kiekert relay, center of image (click to view larger image):
This situation is easily fixed by carefully re-flowing the solder at the affected joints/pins, which should restore consistent electrical connectivity.
This post is not specifically a HOW-TO on how to do this -- more of a heads-up that the problem exists, and how to identify it for proper remediation.
NOTE: For later G-wagens, such as the 2002 and up MBUSA models, they do not employ the same Kiekert relay, though they do use the same door actuators. The procedure and issues regarding the electric door locks becoming inoperative on these newer G-wagens is a totally different problem than on the earlier models, with different diagnosis and components involved.
SECOND NOTE: ALL long-wheelbase G-wagens from 1990 through 2017 use the "slave" door lock actuators on the front passenger and two rear doors. G-wagens from 1990 through 2001 use the five-wire "Master" actuator on the driver's side door. G-wagens from 2002 through 2017 use the same "slave" door lock actuator on the driver's side door as used on the other three doors (a total of four identical two-wire "slave" actuators for these trucks). G-wagens from 1990 through 2010 use the same fuel flap actuator.