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3.(K2) SENSOR SIGNAL CIRCUIT SHORTED TO GROUND
Turn the ignition off.
Disconnect the ECM harness connector.
Check connectors - Clean/repair as necessary.
Measure the resistance between the engine ground and the (K2) tem-
perature sensor signal circuit at the sensor harness connector.
Istheresistancemorethan100kohms?
Ye s>>
Go To 4
No>>
Repair or replace the short harness.
Perform POWERTRAIN VERIFICATION TEST VER - 1
(DIESEL). (Refer to 8 - ELECTRICAL/ELECTRONIC CON-
TROL MODULES/ENGINE CONTROL MODULE - DIAG-
NOSIS AND TESTING)
4.WIRING HARNESS SHORTED
Measure the resistance between the (K2) signal circuit and all other cir-
cuits at the ECM harness connector.
Istheresistancemorethan100kohms?
Ye s>>
Go To 5
No>>
Repair or replace shorted wiring harness
Perform POWERTRAIN VERIFICATION TEST VER - 1
(DIESEL). (Refer to 8 - ELECTRICAL/ELECTRONIC CON-
TROL MODULES/ENGINE CONTROL MODULE - DIAG-
NOSIS AND TESTING)
Page 514 of 5267
5.ECM
Reconnect the ECM harness connectors.
Turn the ignition on.
With the scan tool, erase DTCs.
While monitoring the scan tool, Disconnect the temperature sensor harness connector.
Did the DTC P0118 set?
Ye s>>
Refer to the INTERMITTENT CONDITION Symptom (Diagnostic Procedure). (Refer to 9 - ENGINE -
DIAGNOSIS AND TESTING)
No>>
Replace the ECM.
Perform POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL). (Refer to 8 - ELECTRICAL/ELEC-
TRONIC CONTROL MODULES/ENGINE CONTROL MODULE - DIAGNOSIS AND TESTING)
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P0118-ENGINE COOLANT TEMPERATURE (ECT) SENSOR VOLTAGE TOO HIGH
For a complete wiring diagramRefer to Section 8W.
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When Monitored:
With ignition on and battery voltage greater than 10.4 volts.
Set Condition:
The circuit voltage to the ECM is above a calibrated threshold for a certainperiod of time.
Possible Causes
COOLANT TEMPERATURE SENSOR
INTERMITTENT CONDITION
(K2) SIGNAL CIRCUIT OPEN
(K914) SENSOR RETURN CIRCUIT OPEN
(K2) SIGNAL CIRCUIT SHORTED
ECM
Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. (Refer to 9 - ENGINE -
DIAGNOSIS AND TESTING)
Diagnostic Test
1.COOLANT TEMPERATURE SENSOR
Disconnect the coolant temperature sensor harness connector.
Check connectors - Clean/repair as necessary.
Measure the resistance of the coolant temperature sensor.
Is the resistance between 300 and 90k ohms?
Ye s>>
Go To 2
No>>
Replace the coolant temperature sensor.
Perform POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL). (Refer to 8 - ELECTRICAL/ELEC-
TRONIC CONTROL MODULES/ENGINE CONTROL MODULE - DIAGNOSIS AND TESTING)
2.INTERMITTENT CONDITION
Reconnect the disconnected coolant temp sensor harness connector.
With the scan tool, erase DTCs.
With the scan tool, read DTCs.
Did the DTC return?
Ye s>>
Go To 3
No>>
Refer to the INTERMITTENT CONDITION Symptom (Diagnostic Procedure). (Refer to 9 - ENGINE -
DIAGNOSIS AND TESTING)
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3.HIGH RESISTANCE IN CIRCUIT
Turn the ignition off.
Disconnect the ECM harness connector.
Check connectors - Clean/repair as necessary.
Measure the resistance between the (K2) temperature sensor signal
and (K914) return circuit at the ECM harness connector with the coolant
temp sensor harness connected.
Is the resistance between 300 and 90k ohms?
Ye s>>
Go To 6
No>>
Go To 4
4.(K2) SIGNAL CIRCUIT OPEN
Disconnect the coolant temperature sensor harness connector.
Measure the resistance of the (K2) coolant temperature sensor signal
circuit between the coolant temperature sensor connector and the ECM
connector.
Is the resistance less than 10 Ohms?
Ye s>>
Go To 5
No>>
Repair or replace the open (K2) signal circuit.
Perform POWERTRAIN VERIFICATION TEST VER - 1
(DIESEL). (Refer to 8 - ELECTRICAL/ELECTRONIC CON-
TROL MODULES/ENGINE CONTROL MODULE - DIAG-
NOSIS AND TESTING)
Page 518 of 5267
5.(K914) SENSOR RETURN CIRCUIT OPEN
Measure the resistance of the (K914) coolant temperature sensor return
circuit between the coolant temperature sensor connector and the ECM
connector.
Is the resistance less than 10 Ohms?
Ye s>>
Go To 6
No>>
Repair or replace the open (K914) sensor return circuit.
Perform POWERTRAIN VERIFICATION TEST VER - 1
(DIESEL). (Refer to 8 - ELECTRICAL/ELECTRONIC CON-
TROL MODULES/ENGINE CONTROL MODULE - DIAG-
NOSIS AND TESTING)
6.(K2) SIGNAL CIRCUIT SHORTED
Measure the resistance of (K2) signal circuit to all other circuits at the
ECM harness connector.
Istheresistancemorethan100kohms?
Ye s>>
Go To 7
No>>
Repair or replace the (K2) coolant temperature sensor sig-
nal circuit.
Perform POWERTRAIN VERIFICATION TEST VER - 1
(DIESEL). (Refer to 8 - ELECTRICAL/ELECTRONIC CON-
TROL MODULES/ENGINE CONTROL MODULE - DIAG-
NOSIS AND TESTING)
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7.ECM
Reconnect the ECM harness connectors.
Turn the ignition on.
With the scan tool, erase DTCs.
While monitoring with scan tool, use a jumper wire and connect the
sensor (K2) signal circuit to the (K914) sensor return circuit at the sen-
sor connector.
Did the DTC P0117 set?
Ye s>>
Te s t C o m p l e t e .
No>>
Replace the ECM.
Perform POWERTRAIN VERIFICATION TEST VER - 1
(DIESEL). (Refer to 8 - ELECTRICAL/ELECTRONIC CON-
TROL MODULES/ENGINE CONTROL MODULE - DIAG-
NOSIS AND TESTING)
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P0128-THERMOSTAT RATIONALITY
For a complete wiring diagramRefer to Section 8W.
When Monitored:
While the engine is running.
Set Condition:
The coolant temperature does not rise by a calibrated amount over a calibratedamountoftime.
Possible Causes
COOLING FAN
COOLANT TEMPERATURE SENSOR
THERMOSTAT
Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. (Refer to 9 - ENGINE -
DIAGNOSIS AND TESTING)
Diagnostic Test
1.COOLING FAN
NOTE: refer to the no trouble code test*Fan Operation Testto ensure the fan is operating properly.
Is the cooling fan operating properly?
Ye s>>
Go To 2
No>>
Repair the cooling fan.
Perform POWERTRAIN VERIFICATION TEST VER - 2 (DIESEL). (Refer to 8 - ELECTRICAL/ELEC-
TRONIC CONTROL MODULES/ENGINE CONTROL MODULE - DIAGNOSIS AND TESTING)
2.COOLANT TEMPERATURE SENSOR
Operate the engine for 10 minutes while monitoring the coolant temperaturewiththescantool.
Did the coolant temperature change over time while the engine was running?
Ye s>>
Go To 3
No>>
Replace the coolant temperature sensor.
Perform POWERTRAIN VERIFICATION TEST VER - 2 (DIESEL). (Refer to 8 - ELECTRICAL/ELEC-
TRONIC CONTROL MODULES/ENGINE CONTROL MODULE - DIAGNOSIS AND TESTING)
3.THERMOSTAT
NOTE: refer to the no trouble code test*Thermostat Testto ensure the thermostat is operating properly.
is the thermostat operating properly?
Ye s>>
Te s t C o m p l e t e .
No>>
Replace the thermostat.
Perform POWERTRAIN VERIFICATION TEST VER - 2 (DIESEL). (Refer to 8 - ELECTRICAL/ELEC-
TRONIC CONTROL MODULES/ENGINE CONTROL MODULE - DIAGNOSIS AND TESTING)