Inspection Procedure 2

Tachometer does not Work.






CIRCUIT OPERATION
- The tachometer power is supplied from the ignition switch (IG) circuit.
- The tachometer calculates the engine revolution r/min) according to the ECM signals to operate the needle.

TECHNICAL DESCRIPTION (COMMENT)
The cause may be ECM signals are not transmitted, or combination meter error.

TROUBLESHOOTING HINTS
- Malfunction of the combination meter (printed circuit board or speedometer and tachometer)
- Malfunction of the ECM
- Damaged wiring harness or connectors

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
- MB991911: M.U.T.-III Main Harness B

STEP 1. Check the other meters.
Check to see that the speedometer, fuel gauge and water thermometer operate normally.

Q: Do all other meters operate?

YES Go to Step 2.

NO Refer to INSPECTION PROCEDURE 5.

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

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. Read the MFI system diagnostic trouble code.

Q: Is DTC output to the MFI system?

YES: Refer to Multiport Fuel Injection (MFI) Diagnosis.

NO: Go to Step 3.

STEP 3. Check combination meter connector C-01 and ECM connector C-119 for loose, corroded or damaged terminals, or terminals pushed back in the connector.

Q: Are combination meter connector C-01 and ECM connector C-119 in good condition?

YES: Go to Step 4.

NO: Repair or replace the damaged components). Refer to Harness Connector Inspection. The speedometer should work normally.

STEP 4. Check the wiring harness between combination meter connector C-01 (terminal 11) and ECM connector C-119 (terminal 45).

NOTE: Also check joint connector C-105 and intermediate connector C-123 for loose, corroded, or damaged terminals, or terminals pushed back in the connector. If joint connector C-105 or intermediate connector C-123 are damaged, repair or replace the connector as described in Harness Connector Inspection.

Q: Are the wiring harness between combination meter connector C-01 (terminal 11) and ECM connector C-119 (terminal 45) in good condition?

YES: Go to Step 5.

NO: Repair the wiring harness. The speedometer should work normally.

STEP 5. Replace the combination meter and check operation.

Q: Does the tachometer operate?

YES: There is no action to be taken.

NO: Replace the ECM. The tachometer should work normally.