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Malfunction of ETACS-ECU power supply circuit
 
 
 
 
 
 
TECHNICAL DESCRIPTION (COMMENT)
If the ETACS-ECU functions do not work at all, the ETACS-ECU power supply system, ground system, or ETACS-ECU may have a problem.
 
 
TROUBLESHOOTING HINTS
  • The wiring harness or connectors may have loose, corroded, or damaged terminals, or terminals pushed back in the connector
  • The ETACS-ECU may be defective
 
 
DIAGNOSIS
Required Special Tools:
  • MB991223: Harness Set
  • MB992006: Extra Fine Probe
STEP 1. Check ETACS-ECU connectors C-415 and C-417 for loose, corroded or damaged terminals, or terminals pushed back in the connector.
Is ETACS-ECU connectors C-415 and C-417 in good condition?
Go to Step 2.
Repair or replace the damaged component(s). Refer to GROUP 00E, Harness Connector Inspection .
 
STEP 2. Check the ground circuit to the ETACS-ECU. Measure the resistance at ETACS-ECU connectors C-415 and C-417.
(1) Disconnect ETACS-ECU connector C-415 and C-417 and measure the resistance available at the wiring harness side of the connector.
(2) Measure the resistance value between ETACS-ECU connector C-415 terminal 17 and ground.
  • The resistance should be 2 ohms or less.
(3) Measure the resistance value between ETACS-ECU connector C-417 terminal 15 and ground.
  • The resistance should be 2 ohms or less.
Is the measured resistance 2 ohms or less?
Go to Step 4.
Go to Step 3.
 
STEP 3. Check the wiring harness between ETACS-ECU connector C-415 (terminal 17) or C-417 (terminal 15) and the ground.
  • Check the ground wires for open circuit.
Is the wiring harness between ETACS-ECU connector C-415 (terminal 17) or C-417 (terminal 15) and the ground in good condition?
No action is necessary and testing is complete.
The wiring harness may be damaged or the connector(s) may have loose, corroded or damaged terminals, or terminals pushed back in the connector. Repair the wiring harness as necessary.
 
STEP 4. Check ETACS-ECU connectors C-406 and C-408 for loose, corroded or damaged terminals, or terminals pushed back in the connector.
Is ETACS-ECU connectors C-406 and C-408 in good condition?
Go to Step 5.
Repair or replace the damaged component(s). Refer to GROUP 00E, Harness Connector Inspection .
 
STEP 5. Check the battery power supply circuit to the ETACS-ECU. Measure the voltage at ETACS-ECU connectors C-406 and C-408.
(1) Disconnect ETACS-ECU connectors C-406 and C-408 measure the voltage available at the wiring harness side of the connector.
(2) Measure the voltage between ETACS-ECU connector C-406 terminal 2 and ground.
  • The voltage should measure approximately 12 volts (battery positive voltage).
(3) Measure the voltage between ETACS-ECU connector C-408 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 7.
Go to Step 6.
 
STEP 6. Check the wiring harness between ETACS-ECU connector C-408 (terminal 1) or C-406 (terminal 2) and the fusible link (34) or (36).
  • Check the power supply line (battery supply) for open circuit and short circuit.
Is the wiring harness between ETACS-ECU connector C-408 (terminal 1) or C-406 (terminal 2) and the fusible link (34) or (36) in good condition?
No action is necessary and testing is complete.
The wiring harness may be damaged or the connector(s) may have loose, corroded or damaged terminals, or terminals pushed back in the connector. Repair the wiring harness as necessary. The system should communicate with the ETACS-ECU normally.
 
STEP 7. Retest the system
Check that the ETACS-ECU functions work normally.
Is the check result satisfactory?
The procedure is complete. (If no malfunctions are found in all steps, an intermittent malfunction is suspected. Refer to GROUP 00, How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunction ).
Replace the ETACS-ECU.