Procedure 4 - Coolant Temp Gauge Inoperative

Engine Coolant Temperature Gauge Circuit:

Connectors:

CIRCUIT OPERATION
- The ignition switch (IG1) circuit is the power source for the fuel 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)
If the ignition switch (IG1) circuit is open, the gauge needle will not move at all. If the ground circuit is open, the gauge needle will move up to its extreme position.

TROUBLESHOOTING
- Malfunction of the engine coolant temperature gauge unit
- Malfunction of the combination meter (printed-circuit board or engine coolant temperature gauge assembly)
- Damaged harness wires or connectors

DIAGNOSIS
Required Special Tool:
MB991223: Harness Set

STEP 1. Check the speedometer operation.
If the speedometer does not work normally, refer to Inspection Procedure 1.
If the speedometer works normally, go to Step 2.




STEP 2. Check the engine coolant temperature sensor signal circuit at the engine coolant temperature sensor connector B-08.
1. Disconnect the engine coolant temperature sensor connector B-08 and measure at the harness side.
2. Turn the ignition switch to "ON" position.
3. Voltage between terminal 1 and ground.
- Voltage should be approximately 9 volts or more.
If less than approximately 9 volts, go to Step 3. If approximately 9 volts or more, go to Step 5.

2.4L Engine:

3.0L Engine:

STEP 3. Check the engine coolant temperature sensor connector B-08 and combination meter connector C-43 for damage.
If the engine coolant temperature sensor connector B-08 and combination meter connector C-43 are damaged, repair or replace it. Refer to Harness Connector Inspection.
The engine coolant temperature gauge should work normally. If the connectors are in good condition, go to Step 4.

2.4L Engine:

3.0L Engine:

STEP 4. Check the harness wires between engine coolant temperature sensor connector B-08 and combination meter connector C-43.

NOTE: After checking intermediate connector C-28, check the wire. If intermediate connector C-28 is damaged, repair or replace it. Refer to Harness Connector Inspection.

If the harness wires between engine coolant temperature sensor connector B-08 and combination meter connector C-43 are damaged, repair them.
The engine coolant temperature gauge should work normally.

If the harness wires are in good condition, repair or replace the combination meter (printed-circuit board or engine coolant temperature gauge assembly).
The engine coolant temperature gauge should work normally.




STEP 5. Check the engine coolant temperature gauge unit.
1. Drain the engine coolant.
2. Remove the engine coolant temperature gauge unit.
3. Immerse the unit in 78 °C (150 °F) water to measure the resistance.
- Resistance should be 104 ± 13.5 Ohms.
If resistance readings are not within specifications, replace the engine coolant temperature gauge unit.
The engine coolant temperature gauge should work normally.

If normal, repair or replace the combination meter (printed-circuit board or engine coolant temperature gauge assembly).
The engine coolant temperature gauge should work normally.