Inspection Procedure 10

INSPECTION PROCEDURE 10: Engine Coolant Temperature Gauge does not Work (other meters work).

CIRCUIT OPERATION
The engine coolant temperature sensor sends signal to the combination meter via the powertrain control module and the CAN bus line.

TECHNICAL DESCRIPTION (COMMENT)
If only the engine coolant temperature gauge does not operate, the powertrain control module system, the combination meter, the wiring harness or its connector may be defective.

TROUBLESHOOTING HINTS
- Malfunction of the powertrain control module
- Malfunction of the combination meter
- The wiring harness or connectors may have loose, corroded, or damaged terminals, or terminals pushed back in the connector

DIAGNOSIS

Required Special Tools:
- MB991958: Scan Tool (M.U.T.-III Sub Assembly)
- MB991824: Vehicle 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 MB991824, diagnose the CAN bus line.







1. Connect scan tool MB991958 to the data link connector.
2. Turn the ignition switch to "ON" position.
3. Diagnose the CAN bus line.

Q: Is the check result satisfactory?

YES : Go to Step 2.

NO : Repair the CAN bus lines. On completion, go to Step 5.

STEP 2. Using scan tool MB991958, read MFI diagnostic trouble code.

Check if an MFI system DTC is set.

Q: Is the DTC set?

YES : Diagnose the MFI system by referring to MFI Diagnosis - Diagnostic Trouble Code Chart Diagnostic Trouble Code Descriptions [2.4L ENGINE] or MFI Diagnosis - Diagnostic Trouble Code Chart Diagnostic Trouble Code Descriptions [3.8L ENGINE]. On completion, go to Step 5.

NO : Go to Step 3.

STEP 3. Using scan tool MB991958, check data list.







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.

1. Connect scan tool MB991958 to the data link connector.
2. Turn the ignition switch to the "ON" position.
3. Set scan tool MB991958 to the data reading mode.
- Item 8C: Engine coolant temperature gauge
- Engine coolant temperature and M.U.T.-III displayed values agree with each other.

- Item 8E: Coolant Temp. confirmation flag
- Normal condition: ON

4. Turn the ignition switch to the "LOCK" (OFF) position.

Q: Is the check result normally?

YES : It can be assumed that this malfunction is intermittent.

NO : Go to Step 4.

STEP 4. Using scan tool MB991958, check actuator test.







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.

1. Connect scan tool MB991958 to the data link connector.
2. Turn the ignition switch to the "ON" position.
3. Set scan tool MB991958 to the actuator test mode.
- Item 88: Engine coolant Temp. gauge: 0° C (32° F)
- Engine coolant temperature gauge shows 0° C (32° F)

- Item 89: Engine coolant Temp. gauge: 85° C (185° F)
- Engine coolant temperature gauge shows 85° C (185° F)

- Item 8A: Engine coolant Temp. gauge: 126° C (259° F)
- Engine coolant temperature gauge shows 126° C (259° F)

4. Turn the ignition switch to the "LOCK" (OFF) position.

Q: Is the check result normally?

YES : Go to Step 5.

NO : Replace the combination meter.

STEP 5. Retest the system.

Check to see that the engine coolant temperature gauge operates normally.

Q: Is the check result satisfactory?

YES : The procedure is complete. (If no malfunctions are found in all steps, an intermittent malfunction is suspected.)

NO : Replace combination meter and then go to step 1.