Keyless Entry System - Modifications
REF. NO. 80/20ATO: OUR MERCEDES-BENZ PASSENGER CAR DEALERS
DATE: July 1994 (supercedes S.I. 80/20, April 1994)
Revision: Text revised including new information on IR transmitter key and system desynchronizaton.
SUBJECT:
MODELS 129, 140 AND 202
A. INFRARED REMOTE CENTRAL LOCKING (IRCL)
B. INFRARED (IR) TRANSMITTER FOR IRCL
C. SYNCHRONIZATION OF IRCL
D. DE-SYNCHRONIZATION OF IRCL
E. CENTRAL LOCKING SYSTEM MODIFICATIONS
A. INFRARED REMOTE CENTRAL LOCKING (IRCL)
Modified functions
Model 129
As of January 1994, the following modifications have been phased-in:
^ The IRCL control module no longer checks the rotary tumbler microswitches (S87s2 and S88/1), right front door actuator (S48) and the trunk lock actuator (S49) to detect an open door or trunk lid. Therefore, the red receiver unit lamps (at each receiver unit) will always flash for approx. 3 seconds, even if a door or the trunk lid is open (previously, 10 seconds if a door or trunk lid is open).
^ The IRCL receiver unit lamps (red or green) will illuminate only at the receiver which receives the signal.
^ Manually locking or unlocking using the mechanical key will not illuminate the receiver unit lamps (red or green).
^ The starter relay module (K38) is activated by a ground side signal from the PSE control module.
The interior central locking (ICL) system can only be activated or deactivated with the infrared (IR) transmitter, except when the system was previously activated by the mechanical lock at the glove box. The mechanical key cannot operate the ICL system from outside the vehicle.
The IRCL control module will receive an input signal from terminal 15 for ignition key recognition (in ignition switch position 1 or 2), instead of receiving it from the warning buzzer switch.
As previously, the central locking system (CL), anti-theft alarm (ATA) and convenience feature (CF) can be activated by the IRCL system.
Model 140
As of July 1993, the following modifications have been phased-in:
^ The IRCL receiver unit lamps (red or green) will illuminate only at the receiver which receives the signal.
^ Manually locking or unlocking using the mechanical key will not illuminate the receiver unit lamps (red or green).
As of December 1993, the following modifications have been phased-in:
^ The IRCL control module no longer checks the rotary tumbler microswitches (S87/2, S87/3, S87/6, and S88/1) and left front door actuator (S47) to detect an open door or trunk lid. Therefore, the red receiver unit lamps (at each receiver unit) will always flash for approx. 3 seconds, even if a door or the trunk lid is open (previously, 10 seconds if a door or trunk lid is open).
^ The starter relay module (K38) is activated by a ground side signal from the PSE control module.
The IRCL control module will receive an input signal from terminal 15 for ignition key recognition (in ignition switch position 1 or 2), instead of receiving it from the warning buzzer switch.
As previously, the central locking system (CL), anti-theft alarm (ATA) and convenience feature (CF) can be activated by the IRCL system.
Modified control modules
In the event a replacement control module is needed for a vehicle without a starter lock-out, it must be replaced with the modified version control module (compatible with the IRCL system with starter lockout). Only the modified version will be available as a replacement part (see "IMPORTANT!" below). The modified control module does not process input signals from the rotary tumbler microswitches in the door and trunk, thereby limiting the illumination time of the red receiver unit lamp to approx. 3 seconds.
Parts Information
IMPORTANT!
In the event a modified IRCL control module (129 820 29 26) is installed in model 129 (production date up to 12/93), the IRCL harness connected to the control module must be modified as follows:
Open the harness connector and remove wire with socket from chamber 26. Insulate socket and wire with electrical tape and tie back wire with loom tie.
Note:
If this modification is not performed the interior trunk lamp will be illuminated when the vehicle is unlocked and the trunk is closed.
B. INFRARED (IR) TRANSMITTER FOR IRCL
Modified size
As of October 1993, the infrared (IR) transmitter has been reduced in size by 40 %.
In the event an IR transmitter needs replacement, it must be replaced with the smaller modified version. Only the modified version is available as a replacement part from the PDC.
When ordering a new IR transmitter, it is necessary to order the complete unit (with mechanical key) since the mechanical parts of the modified and previous version are not interchangeable.
Modified batteries
The modified transmitter uses two, 3 volt lithium batteries (CR 2025) which have a larger diameter and are installed on top of one another.
Battery replacement procedure:
1. Press battery cover (c) off.
2. Replace both batteries (f), while observing correct polarity.
Additional battery cover
A modified battery cover, part no.140 760 00 20 is available which allows the new version IR transmitter to be attached to a key chain.
Note:
Retrofitting of this cover is not a warranty item.
C. SYNCHRONIZATION OF IRCL
Models 129 and 140 as of December 1993
IRCL control module part nos. 129 820 29 26 and 202 820 43 26.
These control modules use a new synchronization procedure:
1. Aim infrared (IR) transmitter sender window (a) at a receiver and press button (b) momentarily (Figure 3).
2. Switch on ignition with the mechanical key within 30 seconds. This will synchronize and enable the control module to recognize the IR transmitter.
D. DE-SYNCHRONIZATION OF IRCL
Model 140
Model 129 as of January 1994
IRCL control module part no.129 820 29 26
1. In the event one of the infrared transmitters is lost, that transmitter can be desynchronized, so that the IRCL control module will no longer recognize or respond to it.
2. To de-synchronize the system, ground the IRCL pin in the data link connector (X11/4) for 30-40 seconds with the ignition ON. Model 140 can also be de-synchronized using the impulse counter scan tool or the Hand-Held Tester (HHT).
3. After de-synchronization, the remaining infrared transmitters must be synchronized (as explained in section C above). Thus, if an IR transmitter is lost, only the mechanical locks need replacement to restore the vehicle's security.
Note:
The system must be re-synchronized after replacing a transmitter.
E. CENTRAL LOCKING SYSTEM MODIFICATIONS
Starter lock-out
Models 129, 140 and 202
As of January 1994, the PSE control module has an output (model 129 pin 6, model 140 pin 1 of connector 2 and model 202 pin 7 of connector C) going to the starter lock-out relay module (K38). This enables the PSE control module to control the starter lock-out feature.
Unlocking the vehicle from any of the three lock points (or using the IR transmitter), will switch the starter lock-out output to ground, energizing the starter relay module (K38) thereby enabling the vehicle to start with the ignition switch.
Locking the vehicle from any of the three lock points (or using IR transmitter), will interrupt starter lockout output to ground, which de-energizes the starter relay module (K38) and will prevent the vehicle from starting.
If the vehicle is locked from the trunk, then entered through an already open door, the vehicle will not start. Therefore, customers should be advised of this scenario to prevent unnecessary service calls.
Note:
Since the assignment of the pin connectors has been changed, the PSE control module installed in models 129 and 202 with starter lock-out output may not be installed to models 129 and 202 without starter lock-out output.
Parts Information
PSE control module with starter lock-out output
Pressurizing and depressurizing central locking
Model 129
The two vacuum elements under the driver's and passenger seats have been eliminated with introduction of the PSE control module with starter lock-out output. For the purpose of pressurizing and depressurizing the central locking system, the PSE control module with starter lock-out output will briefly run in the opposite direction after reaching the shut-off pressure. This ensures immediate locking after unlocking or vice versa without using excessive force.