Inspection Procedure 2

Tachometer does not Work.

Tachometer Circuit:

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

TECHNICAL DESCRIPTION (COMMENT)
The cause is thought to be because PCM or ECM signals are not transmitted or due to combination meter error.

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

DIAGNOSIS

Required Special Tools:
- MB991223: Harness Set
- MB991958: Scan Tool (MUT-III Sub Assembly)
- MB991824: Vehicle Communication Interface (V.C.I.)
- MB991827: MUT-III USB Cable
- MB991910: MUT-III Main Harness A

STEP 1. Check with other meter.
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.

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

CAUTION: To prevent damage to scan tool MB991958, always turn the ignition switch to "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 Group 13A, Multiport Fuel Injection (MFI) DIAGNOSIS.


NO: Go to Step 3.

STEP 3. Check combination meter connector C-04 and PCM or ECM connector C-111 for damage.

Q: Are combination meter connector C-04 and PCM or ECM connector C-111 in good condition?

YES: Go to Step 4.

NO: Repair or replace the connector. Refer to Harness Connector Inspection. The tachometer should work normally.

STEP 4. Check the wiring harness between combination meter connector C-04 (terminal 47) and PCM or ECM connector C-111 (terminal 87).

NOTE: Also check intermediate connector C-105. If intermediate connector C-105 is damaged, repair or replace the connector as described in Harness Connector Inspection.

Q: Are the wiring harness between combination meter connector C-04 (terminal 47) and PCM ECM connector C-111 (terminal 87) in good condition?

YES: Go to Step 5.

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

STEP 5. Replace the combination meter and check.

Q: Does the tachometer operate?

YES: There is no action to be taken.

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