IGNITION KEY REMINDER TONE ALARM
The ignition key reminder tone alarm will sound under the following condition, and warn the driver to remove the ignition key.
- The driver's door is opened when the ignition switch is at "LOCK" (OFF) or "ACC" position without removing the ignition key.
However, the light reminder tone alarm will take precedence over this function.
The immobilizer system consists of the ignition key, the key ring antenna, the immobilizer-ECU, and the engine control module (ECM). The ignition key has a built-in transponder. Only the registered ignition key permits the engine to start, therefore, the engine can never be started by means of a forged key or by connecting the ignition wiring directly. The system is significantly safe and reliable against theft. In addition, the driver has only to turn the ignition switch to the "ON" position to activate the immobilizer system. If the requirements for starting the engine are not satisfied, the engine will be immobilized. If a registered ignition key is lost, all your ignition keys need to be registered again using scan tool MB991958 (MUT-III Sub Assembly) to ensure security (Refer to ON-VEHICLE SERVICE ). An additional ignition key can be registered as follows (only if no ignition keys are lost)
- Using scan tool MB991958 (MUT-III Sub Assembly) (Refer to ON-VEHICLE SERVICE ).
- By operating two ignition keys that have been already registered (Refer to ON-VEHICLE SERVICE ).
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- After the ignition is switched on, the engine control module sends a control signal and transponder read command signal to the immobilizer ECU.
- When the immobilizer ECU receives the control signal from the engine control module through the key ring antenna, the immobilizer ECU supplies a current and sends random number data to the transponder in the ignition key.
- The transponder uses the random number data to derive an ID code, which is sent to the immobilizer ECU through the key ring antenna.
- The immobilizer ECU compares the ID code that was sent with pre-registered ID codes, and if it matches, a control signal approving ignition is sent to the engine control module. If the ID code does not match (in the case of counterfeit ignition keys, for example), the immobilizer ECU sends a control signal denying ignition to the engine control module, preventing the engine from starting.
To replace immobilizer system related parts, refer to the table below. When the ignition key is re-registered with scan tool MB991958, the originally registered ignition key registration information will be lost.
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The Ignition key reminder tone alarms is controlled by the Simplified Wiring System (SWS). For troubleshooting, refer to SWS DIAGNOSIS .
HOW TO READ DATA LIST (MUT-III)
Required Special Tools
- MB991958: Scan Tool (MUT-III Sub Assembly) MB991824: V.C.I. MB991827: USB Cable MB991911: Main Harness B
| CAUTION | To prevent damage to scan tool MB991958, always turn the ignition switch to the "LOCK" (OFF) position before connecting or disconnecting scan tool MB991958. |
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- Connect scan tool MB991958 to the data link connector.
- Turn the ignition switch to "ON" position.
- Select "Interactive Diagnosis" from the start-up screen.
- Select "System select."
- Choose "IMMOBILIZER" from the "POWER TRAIN" tab.
- Select "Data List."
- Choose an appropriate item and select the "OK" button NOTE: Refer to " TRANSPONDER LOCK CHECK ".
HOW TO REGISTER ENCRYPTED CODE
Required Special Tool
- MB991502: Scan Tool (MUT-II)
- MB991958: Scan Tool (MUT-III Sub Assembly)
| CAUTION | Because registering the encrypted codes is done after all previously-registered codes have been erased, you should keep all of the ignition keys that have already been registered accessible. |
If the ignition key, Immobilizer-ECU, ECM is replaced or an ignition key is added, encrypted codes of all the ignition keys must be registered. (A maximum of eight different ignition key can be registered). Moreover, when the immobilizer-ECU has been replaced, you will need to use scan tool MB991958 to register the immobilizer-ECU and input the vehicle secret code and to register the password (secret code) that the owner specifies into the immobilizer-ECU.
If an attempt is made to start the engine with an unregistered ignition key, cranking occurs, but fuel supply is cut off to disable the engine. In approx. 10 seconds, the immobilizer indicator will blink for approx. 30 seconds.
Note. ECM has an encrypted code for immobilizer-ECU, and the encrypted code is registered in the immobilizer-ECU and ignition key.
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KEY ID REGISTRATION
All ignition keys can be registered with scan tool MB991502 or MB991958. Additional ignition keys can be registered with or without scan tool MB9919502 or MB991958.
TRANSPONDER LOCK CHECK
Required Special Tool
- MB991502: Scan Tool (MUT-II)
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- Connect scan tool MB991502 to the 16-pin data link connector.
- Turn the ignition switch to "ON" position.
- At "System Select," press "YES."
- Select "Immobilizer," press "YES".
- Select "Data list" press "YES".
- Confirm "TP LOCK CHECK."
Required Special Tools
- MB991958: Scan Tool (MUT-III Sub Assembly) MB991824: V.C.I. MB991827: USB Cable MB991911: Main Harness B
| CAUTION | To prevent damage to scan tool MB991958, always turn the ignition switch to "LOCK" (OFF) position before connecting or disconnecting scan tool MB991958. |
Follow the procedure below to judge if the ignition key can be overwritten (i.e. the ignition key is correct) or not.
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- Connect the scan tool MB991958 to the data link connector.
- Turn the ignition switch to "ON" position.
- Select "Interactive Diagnosis" from the start-up screen.
- Select "System select."
- Choose "IMMOBILIZER" from the "POWER TRAIN" tab.
- Select "Data List."
- The multi-center display shows whether the ignition key, which has been inserted in the switch, can be rewritten and how many ignition keys have ever been registered.
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- Insert the key into steering lock cylinder to turn the ignition key to the "ACC" position.
- Insert the locking pin with a small cross-tipped screwdriver, etc., and remove the steering lock cylinder.
IGNITION SWITCH CONTINUITY CHECK
Disconnect ignition switch connector C-87 without removing the ignition switch and steering lock cylinder. Then check the continuity.
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- Ignition key reminder switch continuity check. Disconnect key reminder switch connector C-88 without removing the ignition switch and steering lock cylinder. Then check the continuity.
- Ignition key ring antenna check. Check for continuity between terminal 3 and terminal 7. Standard value: 2 ohm or less