Function description of infrared remote control - ra80001400400x(0400)

Central Locking System Model 140 

A. General 

1st version up to 11/94, up to 08/95 

2nd version as of 12/94, as of 09/95 

To improve operating convenience, the central locking and the anti-theft alarm system can be operated with an infrared transmitter in the key head. In addition, any side windows and tilting/sliding roof still open can be closed or the side windows can be opened again within 10 s after central locking.

All processes are displayed by feedback lamps.

Remote control is possible up to a distance of approx. 6 m with the maximum capacity of the transmitter batteries, remote control of the convenience operation up to a distance of approx. 3 m.

The receiver units with feedback lamps are located up to 11/94, up to 08/95 in the front door handles and next to the trunk lid lock cylinder.

As of 12/94, as of 09/95 the receiver unit with feedback lamps is located at the interior mirror. No  receiver unit is located in the front door handles. Only the feedback lamps are installed here (not ).

Only 

Additionally as of model year 95 the trunk lid can be opened by means of the trunk lid remote control by operating the transmitter twice within about 0.8 seconds.

B. Operation 

Unlocking central locking and disarming the anti-theft alarm system 

Point transmitter with the transmission window (a) in the direction of the receiver on the vehicle up to a distance of approx. 6 m away. Press button (b) briefly, green feedback lamp flashes. As soon as all commands have been carried out, the green feedback lamp goes out.

Locking the central locking and arming the ATA 

As with unlocking, point the transmitter window (a) in the direction of the receiver. Press button (b) briefly, red feedback lamp flashes. As soon as all commands have been carried out, the red feedback lamp goes out after approx. 3 seconds. If a command could not be carried out, for example, because a door or the trunk lid is not completely closed, the red feedback lamp continues to flash for up to approx. 10 seconds and on vehicles as of approx. 07/94 only for approx. 3 seconds.

The vehicle must first be unlocked centrally and then locked centrally after the door or trunk lid is closed properly.

Closing the side windows and tilting/sliding roof via the infrared remote control 

When locking, keep button (b) on transmitter pressed down; after approx. 1 second any side windows and tilting/sliding roof which are still open start to close. The closing process is interrupted if the button on the transmitter is released or the infrared beam between the transmitter and the receiver is interrupted.

C. Function 

The infrared remote control can only be operated with the transmitter belonging to the vehicle since the transmitter and the control module installed in the vehicle are matched to one another.

The transmitter transmits the transmitter signal to the receiver as an infrared light beam. The receiver receives the light beam, filters out light from external sources, amplifies the transmitter signal and passes it on to the control module via a control line.

The transmitter signal consists of a fixed code which is additionally coded by a computer. This additional coding changes with each operation. It is thus not possible to decode the transmitter signal.

The control module decodes the transmitter signal and, if the fixed code is correct, operates the central locking, the convenience feature and the anti-theft alarm system. At the same time the control module adjusts to the next transmitter signal and blocks the previous transmitter signal.

If the transmitter is operated outside the reception range, the current transmitter signal changes in the transmitter but not in the control module. If the transmitter is used again in the reception range, the transmitter signal does not agree with that expected by the control module. However since the control module can calculate 250 further switchings, it adjusts to the current transmitter signal.

If the transmitter has been operated outside the reception range more than 250 times, the transmitter must be resynchronized .

Desynchronization 

If a transmitter key is lost, the programmable code portion of the transmitter signal can be desynchronized with the hand-held tester. As a result only the mechanical locking mechanism has to be replaced if a transmitter key is lost. Then, all the transmitter keys belonging to this locking mechanism should be resynchronized .

D. Components 

1st version up to 11/94, up to 08/95 

Sedan

Coupe

2nd version as of 12/94, as of 09/95 

Transmitter key 

An infrared transmitter with transmitter window (a), a pushbutton for operation (b), a battery compartment (c) with 4 batteries (transmitter key up to 09/93) or 2 batteries (transmitter key as of 10/93) and a folding 4-track key (d) are accommodated in the key head. The key can be folded out by operating pushbutton (e).

If a transmitter key is lost, it can be ordered via the usual channels by stating the locking mechanism number.

Up to 8 transmitters can be adapted to a locking mechanism by the manufacturer. The folding key in the transmitter is replaceable.

If transmitter button (b) is operated continuously, the transmitter switches off after approx. 30 s in order to prevent the batteries from discharging.

As of 10/93, the volume of the transmitter key was reduced by approx. 40 %. It is not possible to replace the mechanical key shank of a transmitter key up to 09/93 in a transmitter key as of 10/93.

1. Transmitter key up to 09/93
2. Transmitter key as of 10/93

Infrared spare key and also secondary key function 

As of about 05/95 the customer is supplied with an infrared spare key in addition to his two infrared transmitter keys (except ). With the introduction of this infrared spare key, the spare batteries for the infrared transmitter keys which were enclosed in the car document wallet with the introduction of the driver authorization system stage 2, are now discontinued. The infrared spare key can also be obtained for older models with infrared remote central locking through Central Parts Depot Germersheim.

The spare key (2) has the size of a check card. The spare key can be used to operate the central locking and also the anti-theft alarm system. In addition, the drive authorization system is activated or deactivated by means of the infrared signal. It is not  possible to operate the convenience feature. The spare key (2) houses an infrared transmitter, a pushbutton (b), an LED (a) as a battery check, a battery compartment with two batteries and a mechanical master key (d). The infrared beam is emitted in the middle of the front side of the spare key when the pushbutton (b) is operated.

Spare keys are identified by a code number (3) in this example (stamped on the rear).

To replace the two batteries (f), press in the catch (arrow) and lift off the battery compartment cover (c) of the spare key (2). The same batteries as in the normal infrared transmitter key are used.

If need be, the mechanical master key  (d) can be replaced by a mechanical secondary key.  This can be obtained from the Central Parts Depot Germersheim. The mechanical secondary key cannot be used to operate the lock cylinders of the trunk lid and glovebox. The customer therefore can take advantage of the known benefits when the car is in a workshop or when staying at a hotel.

Receiver units of infrared remote control (A26/1, A26/2, A26/3) up to 11/94, up to 08/95 

From outside, only the infrared window (a) and the two feedback lamps, red (b) and green (c) of the receiver units are visible.

The driver's door (A26/1) and front passenger door (A26/2) receiver units are located in the driver's door handle.

The trunk lid infrared remote control (IRCL) receiver unit (A26/3) is mounted on the trunk lid lock.

Interior mirror infrared remote control receiver unit (A26/7) as of 12/94, as of 09/95 

The receiver unit (A26/7) as well as the two feedback lamps, red (b) and green (c), are housed in the interior mirror.

The receiver units can be replaced individually without stating the locking mechanism number.

IRCL function display (E34) 

No  receiver unit in front door handle, only green and red feedback lamps (not ).

The lock cylinder is concealed by a cap (arrow) which can be removed if need be in order to get into the interior of the car, for example if the transmitter batteries are discharged.

b Red feedback lamp

c Green feedback lamp

Infrared remote control module (N54) up to 11/94, up to 08/95 

The control module in the sedan is located on the reinforcement on the right of the trunk. The control module in the coupe is positioned below the left rear seat. The electrical connection is provided with a plug-in and withdrawal aid. To withdraw, press locking lug and pull up coupling on the cable side.

When replacing the control module or the transmitter, always indicate the locking mechanism number since both parts are matched to one another.

Infrared remote control module (N54) as of 12/94, as of 09/95 

The control module is located at the front right of the firewall behind the passenger airbag (behind airduct).

The 12-pin electrical connection is provided with a plug-in and withdrawal aid. To withdraw, press locking lug and fold over clamp. The 2-pin electrical connection is secured with a lock. Press locking lug and push lock to the side.

E. Immobilizer stage 1a as of 12/93 up to 11/94, up to 08/95 

As of 12/93 up to 11/94, the IRCL control module (N54) has an electrical output (pin 25) to actuate the immobilizer relay (K38) for the function of the immobilizer (open-circuit of the starter current circuit).

If the vehicle is unlocked via one of the three operating points with the transmitter key, the immobilizer output is switched to ground. After the ignition is switched on, the immobilizer relay (K38) picks up and the vehicle can be started.

If the vehicle is locked via one of the three operating points with the transmitter key, ground actuation of the immobilizer relay (K38) is open-circuited via the immobilizer output. The vehicle cannot be started.

For testing the immobilizer output, refer to diagnosis information.

On vehicles as of 12/93 without IRCL, the immobilizer relay (K38) is actuated via the pneumatic system equipment (A37, A37/1).

Immobilizer stage 1 a 

Location of components - immobilizer stage 1a 

Sedan

Coupe

F. Drive authorization system stage 2 as of 12/94, as of 09/95 

The infrared remote central locking control module intervenes in the engine control module in order to effect the drive authorization system stage 2. The system immobilizes the engine management if the car has been locked with the infrared remote control. Although the starter rotates, the engine does not start. Depending on the engine control module the car has a corresponding drive authorization system (IRCL version). There are two versions: an IRCL version with CAN link and a version with PWM link to the engine control module.

Engines with mechanical fuel injection are provided with a drive authorization system shut-off valve control module (DSV) with integrated fuel shut-off valve which interrupts the fuel supply. This control module is likewise linked via the CAN to the IRCL control module.

The drive authorization system and the ATA can be activated or deactivated only with the IRCL. Opening and closing the car with the mechanical key does not have any influence on the drive authorization system or on the ATA. ( : all systems can continued to be operated with IRCL and key.)

The IRCL control module and the engine control module with CAN link are permanently assigned to each other by means of an identification code. This identification code can no longer be erased. It is therefore not possible to install the IRCL control module or the engine control module from another car as a test.

Networked components as of 12/94, as of 09/95 

IRCL control module/drive authorization system shut-off valve control module linked via CAN

IRCL control module/engine control module link via CAN

IRCL control module/engine control module link via PWM

Replacing components of the infrared remote central locking (models with drive authorization system stage 2) 

The infrared control module and the engine control module are permanently assigned to each other by an identification code. For this reason, the infrared lock system number portion of the lock system remains in the car over its entire life, in other words only the mechanical lock system number portion as well as the check digits may change.

What this means if a transmitter key or a mechanical key is lost: 

• IRCL lock system number portion is retained → invalidate lost key by desynchronizing the control module or by revocably or irrevocably blocking the relevant transmitter key.
• Change mechanical lock system number portion → install mechanical lock system with new lock system number at all points. It is then essential to return a sticker with the 8-digit lock system number stating the FIN to Dept. VP/MAM2, Mercedes-Benz AG, 70322 Stuttgart.

What this means if the IRCL control module is faulty: 

• IRCL lock system number portion is retained → install new control module with the same lock system number.

What this means if a mechanical lock element is faulty: 

• Lock system number is retained → replace lock element while retaining the lock system number.

Revocably or irrevocably blocking infrared transmitter keys (models with drive authorization system stage 2) 

With the introduction of the IRCL control modules with the Part No. 210 820 27 26 / 28 26 as of about 09/95, infrared transmitter keys can be revocably  blocked using the hand-held tester. This process of blocking certain transmitter keys is performed menu-prompted with the handheld tester. Revocable blocking or revalidation of particular transmitter keys is possible as from hand-held tester module 06/95.

With the introduction of the drive authorization system stage 2 infrared transmitter keys can be irrevocably  blocked with the hand-held tester. The procedure for blocking particular transmitter keys is performed menu-prompted with the hand-held tester. The irrevocable blocking of a particular transmitter key should only be performed at the expressed wish of the customer  because a transmitter key has been lost.

It is not possible to revalidate transmitter keys which have been irrevocably blocked.

All cars are factory-supplied with the transmitter key "1" and "2". The infrared spare key which is also supplied from about 05/95 will have the number "3". In addition, all consecutively numbered transmitter keys which may have been purchased subsequently should also be allowed for. The existing transmitter keys are recognizable from the numbers stamped in the transmitter key housing. Remove the battery compartment cover on the transmitter keys and read off the identification digits.

This makes it possible to determine the number of the lost key which should be blocked.