Inspection Procedure 1: Power supply circuit check.: Diagnosis
Required Special Tools:
- MB991223: Harness Set
- MB992006: Extra Fine Probe
- MB991958: Scan Tool (M.U.T.-III Sub Assembly)
- MB991824: Vehicles Communication Interface (V.C.I.).
- MB991827: M.U.T.-III USB Cable
- MB991910: M.U.T.-III Main Harness A (Vehicles with CAN communication system)
- STEP 1. Using scan tool MB991958, read the combination meter diagnostic trouble code.
Check if DTC is set to the combination meter.
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.- Connect scan tool MB991958. Refer to "HOW TO CONNECT THE SCAN TOOL (M.U.T.-III) ".
- Turn the ignition switch from "LOCK" (OFF) position to "ON" position.
- Check if DTC is set.
- Turn the ignition switch to the "LOCK" (OFF) position.
Q: Is the DTC set?
YES: Troubleshoot the combination meter (Refer to DIAGNOSTIC TROUBLE CODE CHART ).
NO: Go to Step 2.
- STEP 2. Check combination meter connector C-03 for loose, corroded or damaged terminals, or terminals pushed back in the connector.
Q: Is combination meter connector C-03 in good condition?
YES: Go to Step 3.
NO: Repair the defective connector.
- STEP 3. Check the battery power supply circuit to the combination meter. Measure the voltage at combination meter connector C-03.
- Disconnect the connector, and measure at the wiring harness side.
- Turn the ignition switch to the LOCK (OFF) position.
- Measure the voltage between terminals 1, 24 and ground.
- The voltage should measure approximately 12 volts (battery positive voltage).
Q: Is the measured voltage approximately 12 volts (battery positive voltage)?
YES: Go to Step 5.
NO: Go to Step 4.
- STEP 4. Check the wiring harness between combination meter connector C-03 (terminal 1, 24) and the fusible link (36). NOTE: Also check ETACS-ECU connectors C-307 and C-317 for loose, corroded, or damaged terminals, or terminals pushed back in the connector. If ETACS-ECU connector C-307 or C-317 is damaged, repair or replace the damaged component(s) as described in HARNESS CONNECTOR INSPECTION .
Q: Is the wiring harness between combination meter connector C-03 (terminal 1, 24 and the fusible link (36) in good condition?
YES: The trouble can be an intermittent malfunction (Refer to HOW TO COPE WITH INTERMITTENT MALFUNCTIONS ).
NO: Repair the wiring harness.
- STEP 5. Check the battery power supply circuit to the combination meter. Measure the voltage at combination meter connector C-03.
- Disconnect the connector, and measure at the wiring harness side.
- Turn the ignition switch to the ON position.
- Measure the voltage between terminals 2 and ground.
- The voltage should measure approximately 12 volts (battery positive voltage).
Q: Is the measured voltage approximately 12 volts (battery positive voltage)?
YES: Go to Step 8.
NO: Go to Step 6.
- STEP 6. Using scan tool MB991958, check data list.
Check the input signal from the ignition switch (IG1) in the ETACS-ECU.
- Turn the ignition switch to the "ON" position.
- Check the ETACS data list.
- Turn the ignition switch to the "LOCK" (OFF) position.
Q: Do the scan tool MB991958 display the item "IG voltage" is normal condition?
YES: Go to Step 7.
NO: Troubleshoot the ETACS-ECU. Refer to INSPECTION PROCEDURE 2 "THE IGNITION SWITCH (IG1) SIGNAL IS NOT RECEIVED ".
- STEP 7. Check the wiring harness between combination meter connector C-03 (terminal 2) and the fusible link (34). NOTE: Also check ETACS-ECU connectors C-309 and C-317 for loose, corroded, or damaged terminals, or terminals pushed back in the connector. If ETACS-ECU connector C-309 or C-317 is damaged, repair or replace the damaged component(s) as described in HARNESS CONNECTOR INSPECTION .
Q: Is the wiring harness between combination meter connector C-03 (terminal 2) and the fusible link (34) in good condition?
YES: The trouble can be an intermittent malfunction (Refer to HOW TO COPE WITH INTERMITTENT MALFUNCTIONS ).
NO: Repair the wiring harness.
- STEP 8. Check the ground circuit to the combination meter. Test at combination meter connector C-03.
- Disconnect combination meter connector C-03 and measure the resistance available at the wiring harness side of the connector.
- Measure the resistance value between terminal 13 and ground.
- The resistance should be 2 ohms or less.
Q: Is the measured resistance 2 ohms or less?
YES: Go to Step 10.
NO: Go to Step 9.
- STEP 9. Check the wiring harness between combination meter connector C-03 (terminal 13) and ground.
Q: Is the wiring harness between combination meter connector C-03 (terminal 13) and ground in good condition?
YES: The trouble can be an intermittent malfunction (Refer to HOW TO COPE WITH INTERMITTENT MALFUNCTIONS ).
NO: Repair the wiring harness.
- STEP 10. Retest the system.
Check that the combination meter works normally.
Q: Is the check result satisfactory?
YES: The trouble can be an intermittent malfunction (Refer to HOW TO COPE WITH INTERMITTENT MALFUNCTIONS ).
NO: Replace the combination meter.