DaimlerChrysler Jeep Grand Cherokee 2002, Service Manual

Page: 46 / 284

Symptom:
P0115-ENGINE COOLANT TEMP SENSOR CIRCUIT SIGNAL VOLT-
AGE TOO LOW
When Monitored and Set Condition:
P0115-ENGINE COOLANT TEMP SENSOR CIRCUIT SIGNAL VOLTAGE TOO
LOW
When Monitored: With the ignition on.
Set Condition: The Engine Coolant Temperature Sensor Signal voltage is below 0.073
volt for more than 3 seconds.
POSSIBLE CAUSES
INTERMITTENT CONDITION
ECT SENSOR
ECT SENSOR SIGNAL CIRCUIT SHORTED TO GROUND
ECT SENSOR SIGNAL AND GROUND CIRCUITS SHORTED TOGETHER
ENGINE CONTROL MODULE
TEST ACTION APPLICABILITY
1 Turn the ignition on.
With the DRB, monitor the Engine Coolant Temperature (ECT) Sensor voltage.
Is the ECT Sensor voltage below 0.073 volt? All
Yes
→
Go To 2
No
→
Go To 6
2 Turn the ignition off.
Disconnect the ECT Sensor harness connector.
Turn the ignition on.
With the DRB, read the ECT Sensor voltage.
Is the voltage above 4.0 volts? All
Yes
→
Replace the ECT Sensor in accordance with the Service Informa-
tion.
Perform ROAD TEST VERIFICATION - VER-2.
No
→
Go To 3
3 Turn the ignition off.
Disconnect the ECM harness connectors.
Disconnect the ECT Sensor harness connector.
Measure the resistance between ground and the ECT Sensor Signal circuit.
Is the resistance above 1000 ohms? All
Yes
→
Go To 4
No
→
Repair the ECT Sensor Signal circuit for a short to ground.
Perform ROAD TEST VERIFICATION - VER-2.
38
DRIVEABILITY - DIESEL
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