Symptom Related Diagnostic Procedures

Radio Remote Control In Hand-held Transmitter Does Not Function [996]

The radio remote control function is unavailable under the following five circumstances:
1. Empty battery in hand-held transmitter
Battery replacement restores the full functionality without additional measures. The same applies in the case of an empty vehicle battery.

2. Radio transmitter outside lock-in range
If the transmitter is operated more than 256 times without reaching the associated receiver (e.g. vehicle outside range or vehicle battery disconnected), the vehicle will not recognise the radio transmitter the next time it is operated. If the number of operations is less than 1024, it is possible to perform re-synchronisation as described below:
- Switch on ignition with key and valid transponder.
- Switch off ignition.
- Remove ignition key from steering lock.
- Operate transmitter within 6 seconds after the key has been removed.

The lock-in range has now been reset to zero (as is the case with every recognised transmitter operation).

3. Atmospheric interference or interfering transmitters
The possibility of temporary interference by interference sources, and thus lack of function, cannot be ruled out due to the many small users operating on the radio frequencies permissible for the automotive application. The 996 model can be unlocked with the vehicle key via the door lock in the event of interference. Unlike with the 993, this does not affect the immobilizer. Deactivation of the immobilizer is performed via the transponder in the key head as soon as the key is turned in the steering lock.

4. Energy-saving mode active
In order to keep "breakdowns" resulting from an empty battery to a minimum, the radio receiver, which draws a high closed-circuit current, is switched off in the alarm system control module after a certain time in addition to switch-off of the other loads.
- The radio receiver is switched off if the ignition is not switched on again within five days (120 h OFF time).
- The radio receiver is switched off independently of the locking condition of the vehicle.
- A locked vehicle can be unlocked with the vehicle key. (This does not reactivate the radio receiver). In the case of vehicles for the English and Belgian markets, it must be borne in mind that the alarm system is not switched off. In order to avoid triggering the alarm, the vehicle key with valid transponder must be turned in the steering lock within the vehicle-entering delay of 10 seconds. (This also applies if the vehicle was parked unlocked for longer than five days due to the "passive arming" function (automatic arming of the alarm system 30 seconds after the vehicle is left with the ignition key removed; the central locking system is not activated in this case) that is in use for the Belgian market.)
- If the radio receiver has been deactivated, it can be reactivated only by switching on the ignition again.
- The switch-off time is reset if the ignition is switched on within five days, i.e. the system does not enter energy-saving mode.
- If a valid radio command is recognised within the idle period (terminal 15 off), the switch-off time is not reset.

5. Fault in hand-held transmitter or vehicle
If the LED on the hand-held transmitter stays dark when the transmitter is operated, this is an indication of either an empty battery or a faulty hand-held transmitter. Radio transmission is OK if the LED on the transmitter flashes when the transmitter is operated and the alarm readiness lamp on the dashboard flashes rapidly. If the alarm readiness light stays dark and points 1 to 4 can be excluded, the problem is a system fault of the vehicle.