Jeep Liberty KJ. Manual — part 754
•
When Monitored:
With the ignition switch on and no other S/C Switch DTC’s present.
•
Set Condition:
The S/C Switch #2 signal voltage is not within a valid switch signal range.
Possible Causes
ECM - S/C SIGNAL CIRCUIT OPEN
ECM - S/C SIGNAL CIRCUIT SHORTED TO VOLTAGE
ECM - SENSOR GROUND OPEN
S/C SWITCH SIGNAL CIRCUIT OPEN
S/C SWITCH SIGNAL CIRCUIT OPEN
S/C SWITCH SIGNAL CIRCUIT SHORT TO GROUND
S/C SWITCH SIGNAL CIRCUIT SHORTED TO VOLTAGE
S/C SWITCH SIGNAL CIRCUIT SHORTED TO VOLTAGE
SENSOR GROUND OPEN
SPEED CONTROL SWITCHES
Diagnostic Test
1.
VERIFY S/C SWITCH SIGNAL CIRCUIT VOLTAGE
NOTE: If the ECM detects and stores a DTC, the ECM also stores
the engine/vehicle operating conditions under which the DTC was
set. Some of these conditions are displayed on the scan tool at the
same time the DTC is displayed.
NOTE: Before erasing stored DTCs, record these conditions.
Attempting to duplicate these conditions may assist when check-
ing for an active DTC.
Turn the ignition off.
Disconnect the harness connectors from both S/C Switches.
Turn the ignition on.
Measure the voltage of the S/C Switch #2 Signal circuit at both S/C
Switch harness connectors.
Select the appropriate voltage reading.
4.5 to 5.5 volts at both connectors.
Go To 2
4.5 to 5.5 volts at only one connector.
Repair the S/C Switch Signal circuit that measured below
4.5 volts for an open.
Perform the ECM Verification Test Ver. 1 (Refer to 9 - ENGINE - DIAGNOSIS AND TESTING).
Below 4.5 volts at both connectors.
Go To 4
Above 5.5 volts for either measurement.
Go To 6
9 - 1074
ENGINE DIESEL DIAG
KJ
2.
SENSOR GROUND OPEN
Turn the ignition off.
Disconnect both S/C Switch harness connectors.
Disconnect the ECM harness connectors.
Measure the resistance of the Sensor Ground circuit between each S/C
Switch harness connector and the ECM harness connector.
Is the resistance below 10.0 ohms for each measurement?
Yes
>> Go To 3
No
>> Repair the Sensor Ground circuit for an open.
Perform the ECM Verification Test Ver. 1 (Refer to 9 -
ENGINE - DIAGNOSIS AND TESTING).
3.
ECM - SENSOR GROUND OPEN
Turn the ignition off.
Disconnect one of the S/C Switch harness connectors.
With the scan tool, read the S/C Switch Voltage.
While monitoring the scan tool, connect a jumper wire between the S/C
Switch #2 Signal circuit and the Sensor Ground circuit in the S/C Switch
harness connector.
Does the scan tool display below 0.1 volt with the jumper wire
connected?
Yes
>> Replace the Speed Control Switches.
Perform the ECM Verification Test Ver. 1 (Refer to 9 -
ENGINE - DIAGNOSIS AND TESTING).
No
>> Replace and program the Engine Control Module in accor-
dance with the Service Information.
Perform the ECM Verification Test Ver. 1 (Refer to 9 -
ENGINE - DIAGNOSIS AND TESTING).
KJ
ENGINE DIESEL DIAG
9 - 1075
4.
S/C SWITCH #2 SIGNAL CIRCUIT OPEN
Turn the ignition off.
Disconnect both S/C Switch harness connectors.
Disconnect the ECM harness connectors.
Measure the resistance between the S/C Switch #2 Signal circuit
between both S/C Switch harness connectors and the ECM harness
connector.
Is the resistance below 10.0 ohms for both measurements?
Yes
>> Go To 5
No
>> Repair the S/C Switch #2 Signal circuit that measured
above 10.0 ohms for an open.
Perform the ECM Verification Test Ver. 1 (Refer to 9 -
ENGINE - DIAGNOSIS AND TESTING).
5.
S/C SWITCH #2 SIGNAL CIRCUIT SHORT TO GROUND
Turn the ignition off.
Disconnect both S/C Switch harness connectors.
Disconnect the ECM harness connectors.
Measure the resistance between ground and the S/C Switch #2 Signal
circuit.
Is the resistance above 1000 ohms?
Yes
>> Replace and program the Engine Control Module in accor-
dance with the Service Information.
Perform the ECM Verification Test Ver. 1 (Refer to 9 -
ENGINE - DIAGNOSIS AND TESTING).
No
>> Repair the S/C Switch #2 Signal circuit for a short to
ground.
Perform the ECM Verification Test Ver. 1 (Refer to 9 -
ENGINE - DIAGNOSIS AND TESTING).
9 - 1076
ENGINE DIESEL DIAG
KJ
6.
S/C SWITCH #2 SIGNAL CIRCUIT SHORTED TO VOLTAGE
Turn the ignition off.
Disconnect both S/C Switch harness connectors.
Disconnect the ECM harness connectors.
Remove the ASD Relay from the PDC.
Connect a jumper wire between cavity 30 and cavity 87 of the ASD
Relay connector.
Turn the ignition on.
Measure the voltage of the S/C Switch #2 Signal circuit.
Is the voltage above 1.0 volt?
Yes
>> Repair the S/C Switch #2 Signal circuit for a short to volt-
age.
Perform the ECM Verification Test Ver. 1 (Refer to 9 -
ENGINE - DIAGNOSIS AND TESTING).
No
>> Replace and program the Engine Control Module in accor-
dance with the Service Information.
Perform the ECM Verification Test Ver. 1 (Refer to 9 -
ENGINE - DIAGNOSIS AND TESTING).
KJ
ENGINE DIESEL DIAG
9 - 1077
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