Inspection Procedure 6
INSPECTION PROCEDURE 6: Speedometer does not WorkINSPECTION PROCEDURE 7: The Fuel Gauge Needle Moves Excessively.
CAUTION: When the battery cable is disconnected or the combination meter is removed, the fuel gauge learned value will be erased To let the display unit re-learn it, enter the vehicle speed (by driving the vehicle or entering simulated vehicle speed) and then stop the vehicle
CIRCUIT OPERATION
The output shaft speed sensor sends vehicle signal to the combination meter via the powertrain control module and the CAN bus line
TECHNICAL DESCRIPTION (COMMENT)
If only the speedometer does not operate, the power-train control module system, the combination meter, the wiring harness or its connector may be defective Furthermore, incorrect level of fuel is shown on the gauge, because the display unit can not learn the fuel gauge
TROUBLESHOOTING HINTS
- Malfunction of the combination meter
- Malfunction of the powertrain control module
- 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 (MUT-III Sub Assembly)
- MB991824: Vehicle Communication Interface (VCI)
- MB991827: MUT-III USB Cable
- MB991910: MUT-III Main Harness A (Vehicles with CAN communication system)
STEP 1 Using scan tool MB991958, 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 (Refer to Diagnosis in Information Bus,-Can Bus Diagnostic Chart) On completion, go to Step 5
STEP 2 Using scan tool MB991958, read A/T diagnostic trouble code
Check if an A/T system DTC is set
Q: Is the DTC set?
YES: Refer to Automatic Transaxle Diagnosis - Diagnostic Trouble Code Chart 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 80: Speedometer
- The voltage should equal battery positive voltage
- Item 81: Speedometer (Target)
- The voltage should equal battery positive voltage
4. Turn the ignition switch to the "LOCK" (OFF) position
Q: Is the measured voltage equal battery positive voltage?
YES: It can be assumed that this malfunction is intermittent Refer to How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunction
NO: Go to Step 4
STEP 4 Check the speedometer
Use scan tool MB991958 to enter simulated vehicle speed
1. Connect scan tool MB991958 to the data link connector
2. Turn the ignition switch to "ON" position
3. Select "Interactive Diagnosis" from the start-up screen
4. Select "System Select"
5. Choose "Meter" from the "BODY" tab
6. Select "Simulated vehicle Speed Output"
OK: The speedometer shows that simulated vehicle speed
Q: Is the check result satisfactory?
YES: Go to Step 5
NO: Replace the combination meter, then go to Step 5
STEP 5 Retest the system
Check that the speedometer 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 How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunction)
NO: Replace the combination meter