Inspection Procedure 8
INSPECTION PROCEDURE 8: Tachometer does not work (other meters work).CIRCUIT OPERATION
The ECM [M/T] or PCM [A/T] sends ignition signal to the combination meter via CAN bus line.
TECHNICAL DESCRIPTION (COMMENT)
If only the tachometer does not operate, the ECM [M/T] or PCM [A/T] system may not be sending ignition signal, or the combination meter, the wiring harness or its connector may be defective.
TROUBLESHOOTING HINTS
- 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: V.C.I.
- MB991827: M.U.T.-III USB Cable
- MB991910: M.U.T.-III Main Harness A
STEP 1. Using scan tool MB991958, diagnose the CAN bus line.
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 "ON" position.
3. Diagnose the CAN bus line.
4. Turn the ignition switch to the "LOCK" (OFF) position.
Q: Is the check result satisfactory?
YES : Go to Step 2.
NO : Repair the CAN bus lines (Refer to Controller Area Network (CAN), Diagnosis, Can Bus Diagnostic Chart).
STEP 2. Using scan tool MB991958, read MFI system diagnostic trouble code.
Check if the MFI system diagnostic trouble code is set.
1. Turn the ignition switch to "ON" position.
2. Diagnose the CAN bus line.
3. Turn the ignition switch to the "LOCK" (OFF) position.
Q: Is the DTC set?
YES : Refer to MFI Diagnosis - Diagnostic Trouble Code Chart <2.4L ENGINE> or <3.8L ENGINE>.
NO : Go to Step 3.
STEP 3. Using scan tool MB991958, check data list.
1. Turn the ignition switch to the "ON" position.
2. Set scan tool MB991958 to the data reading mode.
- Item 05: Tachometer
- Tachometer displayed value and M.U.T.-III displayed value agree with each other.
3. 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. Refer to General (Body and Chassis), How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunction.
NO : Go to Step 4.
STEP 4. Using scan tool MB991958, check actuator test.
1. Turn the ignition switch to the "ON" position.
2. Set scan tool MB991958 to the actuator test mode.
- Item 4: Tachometer: 0 r/min
- The tachometer displays 0 r/min.
- Item 5: Tachometer: 2,000 r/min
- The tachometer displays 2,000 r/min.
- Item 6: Tachometer: 5,000 r/min
- The tachometer displays 5,000 r/min.
3. 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 that the tachometer works 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. Refer to General (Body and Chassis), How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunction).
NO : Replace the combination meter.