Inspection Procedure 4

Engine coolant temperature gauge does not work.

Engine Coolant Temperature Gauge Circuit:

CIRCUIT OPERATION
- The ignition switch (IG1) circuit is the power source for the engine coolant temperature gauge.
- Resistance value, which the engine coolant temperature gauge unit sends to the combination meter, is dependent on temperature of the engine coolant. This causes circuit current to fluctuate.
- The engine coolant temperature gauge moves the needle according to the circuit current.

TECHNICAL DESCRIPTION (COMMENT)
The cause is thought to be due to malfunction of engine coolant temperature gauge unit or the combination meter.

TROUBLESHOOTING HINTS
- Malfunction of the engine coolant temperature gauge unit
- Malfunction of the combination meter
- Damaged wiring harness or connectors

DIAGNOSIS

Required Special Tool:
MB991223: Harness Set

STEP 1. Check he engine coolant temperature gauge by observing the other meter.
Check to see that the speedometer, tachometer and fuel gauge operate normally.

Q: Do all other meters operate?

YES : Go to Step 2.
NO : Refer to INSPECTION PROCEDURE.

STEP 2. Check the engine coolant temperature gauge unit. Check to see that the engine coolant temperature gauge unit operates normally.

Q: Is the engine coolant temperature gauge unit normal?

YES: Go to Step 3.
NO: Replace the engine coolant temperature gauge unit. The engine coolant temperature gauge should work normally.










STEP 3. Check engine coolant temperature gauge unit connector B-08 and combination meter connector C-102 for damage.

Q: Are engine coolant temperature gauge unit connector B-08 and combination meter connector C-102 in good condition?

YES: Go to Step 4.
NO: Repair or replace the connector(s). Refer to Harness Connector Inspection . The engine coolant temperature gauge should work normally.










STEP 4. Check the wiring harnesses between engine coolant temperature gauge unit connector B-08 (terminal 1) and combination meter connector C-102 (terminal 42).

NOTE: Also check intermediate connector C-25. If intermediate connector C-25 is damaged, repair or replace the connector as described in Refer to Harness Connector Inspection .




Q: Are the wiring harnesses between engine coolant temperature gauge unit connector B-08 (terminal 1) and combination meter connector C-102 (terminal 42) in good condition?

YES: Repair or replace the combination meter. The engine coolant temperature gauge should work normally.
NO: Repair the wiring harness(es). The engine coolant temperature gauge should work normally.