Inspection Procedure E-3: Keyless Entry System: Encrypted Code Cannot Be Registered: Diagnosis

Required Special Tools: 

• MB991223: Test Harness Set
• MB991502: Scan Tool (MUT-II)

1. STEP 1. Check trouble symptom. 

   Q: Can the encrypted code register mode be set? 

   1. YES:  Go to  Step 3.
   2. NO:  Go to Step 2.
2. STEP 2. Check the input signal (by using the Pulse check). 

   Check the input signals from the following switches:

   • Key reminder switch
   • Hazard warning light switch
   CAUTION: To prevent damage to scan tool MB991502, always turn the ignition switch to the "LOCK" (OFF) position before connecting or disconnecting scan tool MB991502.
   1. Connect scan tool MB991502 to the data link connector.
   2. If the switches (see table below), which are applicable for the input signal check, are operated, check if scan tool MB991502 sounds or not.
   PULSE CHECK
   
   

   Item name	Check conditions
   Key reminder switch	Remove and reinsert the ignition key
   Hazard warning light switch	Turn the hazard warning light switch from the "OFF" to "ON" position.

   Q: Does scan tool MB991502 sound when the key reminder switch and the hazard warning light switch are operated? 

   1. YES:  Replace the ETACS-ECU. Check that the encrypted code can be registered in the transmitter.
   2. NO: 
      1. Scan tool MB991502 does not sound when the ignition key is removed and reinserted: See INSPECTION PROCEDURE R-1: ETACS-ECU DOES NOT RECEIVE A SIGNAL FROM THE KEY REMINDER SWITCH .
      2. Scan tool MB991502 does not sound when the hazard warning light switch is turned from "OFF" to "ON": See INSPECTION PROCEDURE R-2: THE ETACS-ECU DOES NOT RECEIVE ANY SIGNAL FROM THE HAZARD WARNING LIGHT SWITCH .
3. STEP 3. Check the transmitter. 

   Q: When the transmitter's battery is replaced, can the encrypted code be registered? 

   1. YES:  No action to be taken.
   2. NO:  Replace the transmitter. If the encrypted code can not be registered by means of the new transmitter, replace the ETACS-ECU. Check that the encrypted code can be registered in the transmitter.