Procedure 2 - Tachometer Inoperative

Tachometer does not work

Tachometer Circuit:

Connectors:

CIRCUIT OPERATION
- The tachometer power is supplied from the ignition switch (IG1) circuit.
- The tachometer receives the ignition signal from the engine control module via the ignition failure sensor.

TECHNICAL DESCRIPTION (COMMENT)
The ignition signal may not be sent from the engine control module, or there may be a malfunction in the power supply or ground circuit.

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

DIAGNOSIS

Required Special Tools:
- MB991223: Harness Set
- MB991502: Scan Tool (MUT-II)

CAUTION: To prevent damage to scan tool MB991502, always turn the ignition switch to the "LOCK" (OFF) position before connecting or disconnecting scan tool.

STEP 1. Check the engine speed signal.
1. Connect scan tool MB991502 to the data link connector.
2. Turn the ignition switch to the "ON" position.
3. Read the MFI system diagnostic trouble code.

Q: Is MFI system DTC P0300 output?

YES: Refer to Computers and Control Systems/Testing.

NO: Go to Step 2.

STEP 2. Check the speedometer operation.

Q: Does the speedometer work normally?

YES: Refer to Inspection Procedure 1.

NO: Go to Step 3.

STEP 3. Check the tachometer signal input circuit at combination meter connector C-01.
1. Disconnect combination meter connector C-01.
2. Start the engine and run at idle.
3. Measure the voltage between terminal 11 and ground.

Q: Is the voltage approximately 10 volts?

YES: Repair or repair the combination meter (printed-circuit board or speedometer and tachometer).

NO: Go to Step 4.

STEP 4. Check ECM or PCM connector C-117 or C-118 , combination meter connector C-01 circuit for damage.

Q: Are ECM or PCM connector C-117 or C-118 , combination meter connector C-01 in good condition?

YES: Go to Step 5.

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

STEP 5. Check the harness wires from combination meter connector C-01, ECM or PCM connector C-117 or C-118 .

NOTE: After checking intermediate connector C-123 and joint connector C-105, check the wires. If intermediate connector C-123 or joint connector C-105 is damaged, repair or replace it.
Refer to Harness Connector Inspection.

Q: Are the harness wires from combination meter connector C-01, ECM or PCM connector C-117 or C-118 in good condition?

YES: There is no action to be taken.

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