[Previous][Next]
Inspection Procedure 1: Power Supply Circuit Check
 
 
 
 
 
 
TECHNICAL DESCRIPTION (COMMENT)
If the gateway-ECU functions do not work at all, power supply to the gateway-ECU, or the gateway-ECU itself 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
  • Malfunction of gateway-ECU
 
 
DIAGNOSIS
Required Special Tools:
  • MB991223: Harness Set
  • MB992006: Extra Fine Probe
STEP 1. Check gateway-ECU connector C-49 for loose, corroded or damaged terminals, or terminals pushed back in the connector.
Is gateway-ECU connector C-49 in good condition?
Go to Step 2.
Repair the damaged parts.
 
STEP 2. Measure the voltage at gateway-ECU connector C-49.
(1) Disconnect the gateway-ECU connector C-49, and measure at the wiring harness side.
(2) Turn the ignition switch to the "LOCK" (OFF) position.
(3) Measure the voltage between the gateway-ECU connector C-49 terminal No. 13 and the body ground.
  • The voltage should measure approximately 12 volts (battery positive voltage).
Is the measured voltage approximately 12 volts (battery positive voltage)?
Go to Step 4.
Go to Step 3.
 
STEP 3. Check the wiring harness between the battery (fusible link No. 36) and gateway-ECU connector C-49 terminal No. 13.
Check the power supply line for open circuit.
noteAlso check the ETACS-ECU connectors C-406 and C-417 for loose, corroded, or damaged terminals, or terminals pushed back in the connector. If ETACS-ECU connectors C-406 and C-417 are damaged, repair or replace the damaged component(s) as described in GROUP 00E, Harness Connector Inspection .
Is the check result normal?
Perform the battery test (Refer to GROUP 54A, Battery Test ) or check the battery terminals for looseness or contamination.
Repair the wiring harness.
 
STEP 4. Measure the voltage at gateway-ECU connector C-49.
(1) Disconnect the gateway-ECU connector C-49, and measure at the wiring harness side.
(2) Turn the ignition switch to the "ON" position.
(3) Measure the voltage between the gateway-ECU connector C-49 terminal No. 12 and the body 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 5.
 
STEP 5. Using scan tool MB991958, check other system data list.
Check the input signal from the ignition switch (IG1) in the ETACS-ECU.
  • Turn the ignition switch to the "ON" position.
 
Item No.Item nameNormal condition
254IG voltageBattery positive voltage
Do the scan tool MB991958 display the item "IG voltage" is normal condition?
Go to Step 6.
Troubleshoot the ETACS-ECU (Refer to Inspection Procedure 2 "ETACS-ECU does not receive any signal from the ignition switch (IG1)." ).
 
STEP 6. Check the wiring harness between the IG1 relay and gateway-ECU connector C-49 terminal No. 12.
Check the power supply line for open circuit.
noteAlso check the intermediate connector C-27 and ETACS-ECU connector C-412 for loose, corroded, or damaged terminals, or terminals pushed back in the connector. If intermediate connector C-27 and ETACS-ECU connector C-412 are damaged, repair or replace the damaged component(s) as described in GROUP 00E, Harness Connector Inspection .
Is the check result normal?
The trouble can be an intermittent malfunction (Refer to GROUP 00, How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunction ).
Repair the wiring harness.
 
STEP 7. Measure the resistance at gateway-ECU connector C-49.
(1) Disconnect the gateway-ECU connector C-49, and measure at the wiring harness side.
(2) Measure the resistance between the gateway-ECU connector C-49 terminal No. 14 and the body ground.
  • The resistance should be 2 ohms or less.
Is the measured resistance 2 ohms or less?
Go to Step 9.
Go to Step 8.
 
STEP 8. Check the wiring harness between the gateway-ECU connector C-49 terminal No. 14 and body ground.
Check the ground wires for open circuit.
noteAlso check the grounding connector C-01 for loose, corroded, or damaged terminals, or terminals pushed back in the connector. If grounding connector C-01 is damaged, repair or replace the damaged component(s) as described in GROUP 00E, Harness Connector Inspection .
Is the check result normal?
The trouble can be an intermittent malfunction (Refer to GROUP 00, How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunction ).
Repair the wiring harness.
 
STEP 9. Retest the system.
Is the check result normal?
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 gateway-ECU (Refer to ).