DaimlerChrysler Jeep Grand Cherokee 2002, Service Manual

Page: 133 / 284

Symptom:
P0579-S/C SWITCH SIGNAL CIRCUIT SIGNAL VOLTAGE TOO
HIGH
POSSIBLE CAUSES
ECM - S/C SIGNAL CIRCUIT OPEN
ECM - S/C SIGNAL CIRCUIT SHORTED TO VOLTAGE
ECM - SENSOR GROUND OPEN
S/C ON/OFF/SET SWITCH
S/C ON/OFF/SET SWITCH SIGNAL CIRCUIT OPEN
S/C SWITCH SIGNAL CIRCUIT SHORTED TO VOLTAGE
SENSOR GROUND OPEN
TEST ACTION APPLICABILITY
1 Turn the ignition off.
Disconnect the S/C ON/OFF/SET button harness connector.
Turn the ignition on.
Measure the voltage of the S/C Switch Signal circuit.
Select the appropriate voltage reading. All
Below 4.5 volts.
Go To 2
Between 4.5 and 5.5 volts.
Go To 3
Above 5.5 volts
Go To 5
2 Turn the ignition off.
Disconnect the S/C ON/OFF/SET Switch harness connector.
Disconnect the ECM harness connectors.
Measure the resistance of the S/C Switch Signal circuit.
Is the resistance below 10.0 ohms? All
Yes
→
Replace and program the Engine Control Module in accordance
with the Service Information.
Perform SPEED CONTROL VERIFICATION - VER-4.
No
→
Repair the S/C ON/OFF/SET Switch Signal circuit for an open.
Perform SPEED CONTROL VERIFICATION - VER-4.
3 Turn the ignition off.
Disconnect the S/C ON/OFF/SET switch harness connector.
Turn the ignition on.
Connect a jumper wire between the S/C Switch Signal circuit and the Sensor Ground
at the ON/OFF/SET Switch harness connector.
With the DRB, read the S/C Switch volts.
Does the DRB display below 0.5 volt? All
Yes
→
Replace the S/C ON/OFF/SET Switch.
Perform SPEED CONTROL VERIFICATION - VER-4.
No
→
Go To 4
125
DRIVEABILITY - DIESEL
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