Inspection Procedure 8: Engine Coolant Temperature Gauge does not Work (Other Meters Work).

COMMENTS ON TROUBLE SYMPTOM
If only the engine coolant temperature gauge does not operate, the engine ECU system, the combination meter, the wiring harness or its connector may be defective.

PROBABLE CAUSES

  • Damaged harness wires and connectors
  • Malfunction of the engine coolant temperature gauge unit
  • Malfunction of combination meter

DIAGNOSIS PROCEDURE

STEP 1. Check the engine coolant temperature gauge circuit.
(1)Disconnect the A-108 engine coolant temperature gauge unit connector.

(2)Connect a test lamp (12 V - 3.4 W to 12 V - 7.0 W) to the wiring harness side connector.
(3)Ignition switch: ON

Q. Does the test lamp illuminate?

Go to Step 5.

Go to Step 2.

STEP 2. Connector check: Combination meter connector C-113 and engine coolant temperature gauge unit connector A-108.



Q. Is combination meter connector C-113 and engine coolant temperature gauge unit connector A-108 in good condition?

Go to Step 3.

Repair or replace the damage component(s).

STEP 3. Retest the system.

Q. Is the engine coolant temperature gauge normal?
The procedure is complete. (If no malfunctions are found in all steps, an intermittent malfunction is suspected. Refer to GROUP 00 / How to Cope with Intermittent Malfunction ).
Go to Step 4.

STEP 4. Check the wiring harness between combination meter connector C-113 (terminal 21) and engine coolant temperature gauge unit connector A-108 (terminal 1).







note Prior to the wiring harness inspection, check intermediate connector C-53 <L.H. drive vehicles> or C-35 <R.H. drive vehicles>, and repair if necessary.

Q. Is the wiring harness between combination meter connector C-113 (terminal 21) and engine coolant temperature gauge unit connector A-108 (terminal 1) in good condition?

Go to Step 6.

Repair or replace the damage component(s).

STEP 5. Check the engine coolant temperature gauge circuit.
(1)Disconnect the A-108 engine coolant temperature gauge unit connector.

(2)Connect a test lamp (12 V - 3.4 W to 12 V - 7.0 W) to the wiring harness side connector.
(3)Ignition switch: ON

Q. Does the engine coolant temperature gauge in the combination meter fluctuate about half of it full scale?

Replace the engine coolant temperature gauge unit.

Go to Step 6.

STEP 6. Retest the system

Q. Is the engine coolant temperature gauge normal?
The procedure is complete. (If no malfunctions are found in all steps, an intermittent malfunction is suspected. Refer to GROUP 00 / How to Cope with Intermittent Malfunction ).
Replace the combination meter.