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Inspection Procedure 2: Malfunction of the ignition switch power supply system
 
 
caution
  • Before replacing the ECU, ensure that the power supply circuit, the ground circuit and the communication circuit are normal.
  • When the ETACS-ECU of vehicles without KOS is replaced, the encrypted code of the ignition key needs to be registered to the ETACS-ECU. (If the encrypted code is not registered, the engine cannot be started. Register the encrypted code as described in Immobilizer System - How to Register Key ID .)
 
 
TECHNICAL DESCRIPTION (COMMENT)
When the power supply system of ignition switch has a problem, none of the equipment and system connected to the ignition switch works even if the ignition switch is operated.
 
 
TROUBLESHOOTING HINTS
  • The ignition switch may be defective
  • The fuse may be defective
  • The ETACS-ECU may be defective
  • The wiring harness or connectors may have loose, corroded, or damaged terminals, or terminals pushed back in the connector
 
 
DIAGNOSIS
Required Special Tools:
  • MB992006: Extra fine probe
  • MB991223: Harness set
STEP 1. Voltage measurement at ignition switch connector
(1) Disconnect the ignition switch connector and measure the voltage at ignition switch connector harness side.
(2) Check the voltage between the ignition switch connector (power supply terminal) and ground.
OK: Is the measured voltage approximately 12 volts (battery positive voltage)
Is the check result normal?
Go to Step 4.
Go to Step 2.
 
STEP 2. Check the fuse.
Is the check result normal?
Go to Step 3.
Replace the fuse. (Check that there is not a short to ground in the circuit of lower reaches before replacing. If there are any problems, replace the fuse after the circuit of lower reaches is repaired.)
 
STEP 3. Check of open circuit in IG+ line between ignition switch connector and ETACS-ECU connector.
Is the check result normal?
Go to Step 4.
Repair the connector(s) or wiring harness.
 
STEP 4. Check the ignition switch.
Refer to .
Is the ignition switch in good condition?
Go to Step 5.
Replace the ignition switch.
 
STEP 5. Retest the system.
Do the device and the system work normally when the ignition switch is operated?
The trouble can be an intermittent malfunction (Refer to GROUP 00 - How to Cope with Intermittent Malfunction ).
Replace the ETACS-ECU.