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Inspection Procedure 2: Defective power supply system of the ignition switch
 
 
cautionWhenever the ECU is replaced, ensure that the input and output signal circuits are normal.
 
 
 
 
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 No.14 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. Check ignition switch connector C-309 for loose, corroded or damaged terminals, or terminals pushed back in the connector.
Is ignition switch connector C-309 in good condition?
Go to Step 2.
Repair the defective connector.
 
STEP 2. Check the battery power supply circuit to the ignition switch. Measure the voltage at ignition switch connector C-309.
(1) Disconnect the connector, and measure at the wiring harness side.
(2) Measure the voltage between terminal 1 and ground.
  • The voltage should measure approximately 12 volts (battery positive voltage).
Is the measured voltage approximately 12 volts (battery positive voltage)?
Go to Step 6.
Go to Step 3.
 
STEP 3. Check the fuse No.14.
Is the check result normal?
Go to Step 4.
Replace the fuse No.14. (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 4. Check ETACS-ECU connector C-417 for loose, corroded or damaged terminals, or terminals pushed back in the connector.
Is ETACS-ECU connector C-417 in good condition?
Go to Step 5.
Repair the defective connector.
 
STEP 5. Check the wiring harness between ignition switch connector C-309 (terminal 1) and ETACS-ECU connector C-417 (terminal 3).
  • Check the battery power supply line for open circuit.
Is the check result normal?
Go to Step 7.
Repair the wiring harness.
 
STEP 6. Check the ignition switch.
Remove the ignition switch. Then check continuity between the switch terminal.
 
Ignition key positionTerminal numberNormal condition
LOCK1 - 2, 1 - 4, 1 - 5, 1 - 6No continuity
ACC1 - 6Continuity exists (2 ohms or less)
ON1 - 2 - 4 - 6Continuity exists (2 ohms or less)
START1 - 2 - 5Continuity exists (2 ohms or less)
Is the ignition switch in good condition?
Go to Step 7.
Replace the ignition switch.
 
STEP 7. Retest the system.
When the ignition switch is operated, do the equipment and system work normally?
The trouble can be an intermittent malfunction (Refer to GROUP 00, How to use Troubleshooting/inspection Service Points - How to Cope with Intermittent Malfunction ).
Replace the ETACS-ECU.