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5.(K107) LDP SWITCH SIGNAL CIRCUIT OPEN
Turn the ignition off.
Disconnect the PCM harness connectors.
Measure the resistance of the (K107) LDP Switch Signal circuit from the
PCM harness connector to LDP harness connector.
Is the resistance below 5.0 ohms?
Ye s>>
Go To 6
No>>
Repair the open in the (K107) Leak Detection Pump Switch
Signal circuit.
Perform POWERTRAIN VERIFICATION TEST. (Refer to 9 -
ENGINE - STANDARD PROCEDURE)
6.(K107) LDP SWITCH SIGNAL CIRCUIT SHORT TO GROUND
Measure the resistance between ground and the (K107) LDP Switch
Signal circuit at the LDP harness connector.
Istheresistancebelow100ohms?
Ye s>>
Repair the short to ground in the (K107) LDP Switch Signal
circuit.
Perform POWERTRAIN VERIFICATION TEST. (Refer to 9 -
ENGINE - STANDARD PROCEDURE)
No>>
Go To 7
7.LEAK DETECTION PUMP
If there are no possible causes remaining, view repair.
Repair
Replace the Leak Detection Pump.
Perform POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)
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8.(K106) LEAK DETECTION PUMP SOLENOID CONTROL CIRCUIT OPEN
Turn the ignition off.
Disconnect the PCM harness connectors.
Measure the resistance of the (K106) LDP Solenoid Control circuit from
the PCM harness connector to the LDP harness connector.
Is the resistance below 5.0 ohms?
Ye s>>
Go To 9
No>>
Repair the open in the (K106) Leak Detection Pump Sole-
noid Control circuit.
Perform POWERTRAIN VERIFICATION TEST. (Refer to 9 -
ENGINE - STANDARD PROCEDURE)
9.(K106) LDP SOLENOID CONTROL CIRCUIT SHORT TO GROUND
Measure the resistance between ground and the (K106) LDP Solenoid
Control circuit.
Istheresistancebelow100ohms?
Ye s>>
Repair the short to ground in the (K106) LDP Solenoid Con-
trol circuit.
Perform POWERTRAIN VERIFICATION TEST. (Refer to 9 -
ENGINE - STANDARD PROCEDURE)
No>>
Go To 10
10.PCM
NOTE: Before continuing, check the PCM harness connector terminals for corrosion, damage, or terminal
push out. Repair as necessary.
Using the schematics as a guide, inspect the wire harness and connectors. Pay particular attention to all Power and
Ground circuits.
If there are no possible causes remaining, view repair.
Repair
Replace and program the Powertrain Control Module per Service Information.
Perform POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)
Page 1435 of 5267
P1499-HYDRAULIC FAN SOLENOID CIRCUIT
For a complete wiring diagramRefer to Section 8W.
Page 1436 of 5267

When Monitored:
Ignition on and engine running.
Set Condition:
An open or shorted condition in the Hydraulic Fan Solenoid control circuitis detected by the Powertrain Control
Module.
Possible Causes
RADIATOR FAN INOP
(K342) FUSED ASD RELAY OUTPUT CIRCUIT
(C240) COOLING FAN CONTROL CIRCUIT OPEN
(C240) COOLING FAN CONTROL CIRCUIT SHORTED TO GROUND
HYDRAULIC FAN
PCM
Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. (Refer to 9 - ENGINE -
DIAGNOSIS AND TESTING)
1.RADIATOR FAN INOP
Ignition on, engine not running.
With the scan tool, perform the Hydraulic Fan Solenoid Test found under Engine Test and Systems Test.
Does the Radiator Fan operate properly?
Ye s>>
Refer to the INTERMITTENT CONDITIONSymptom (Diagnostic Procedure).
Perform POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)
No>>
Go To 2
2.(K342) FUSED ASD RELAY OUTPUT CIRCUIT
Turn the ignition off.
Disconnect the Fan Solenoid harness connector.
Ignition on, engine not running.
With the scan tool, actuate the ASD Relay.
Using a 12-volt test light connect to ground, probe the (K342) Fused
ASD Relay Output circuit at the fan solenoid.
Does the test light illuminate brightly when the ASD Relay is
actuated?
Ye s>>
Go To 3
No>>
Repair the open or short to ground in the (K342) Fused
ASD Relay Output circuit. Inspect the related fuse and
repair as necessary.
Perform POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)
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3.(C240) COOLING FAN SOLENOID CIRCUIT OPEN
Turn the ignition off.
Disconnect the PCM harness connectors.
Measure the resistance of the (C240) Cooling Fan Solenoid Control cir-
cuit from the fan harness connector to the PCM harness connector.
Is the resistance below 5.0 ohms?
Ye s>>
Go To 4
No>>
Repair the open in the (C240) Cooling Fan Control circuit.
Perform POWERTRAIN VERIFICATION TEST. (Refer to 9 -
ENGINE - STANDARD PROCEDURE)
4.(C240) COOLING FAN CONTROL CIRCUIT SHORT TO GROUND
Measure the resistance between ground and the (C240) Cooling Fan
Control circuit.
Istheresistancebelow100ohms?
Ye s>>
Repair the short to ground in the (C240) Cooling Fan Con-
trol circuit.
Perform POWERTRAIN VERIFICATION TEST. (Refer to 9 -
ENGINE - STANDARD PROCEDURE)
No>>
Go To 5
5.HYDRAULIC FAN SOLENOID
Remove the ASD Relay and connect a jumper wire between the (K342) ASD Relay Output terminal and the (A14)
Fused B+ circuit to keep the ASD Output circuit powered up for this step.
Connect another jumper wire to the (C240) Hydraulic Fan Solenoid Control circuit in the PCM harness connector.
Momentarily connect the other end of the jumper wire to ground.
NOTE: Remove the jumper wires before continuing.
Did the solenoid actuate?
Ye s>>
Go To 6
No>>
Replace the Hydraulid Radiator Fan.
Perform POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)
Page 1438 of 5267
6.PCM
NOTE: Before continuing, check the PCM harness connector terminals for corrosion, damage, or terminal
push out. Repair as necessary.
Using the schematics as a guide, inspect the wire harness and connectors. Pay particular attention to all Power and
Ground circuits.
If there are no possible causes remaining, view repair.
Repair
Replace and program the Powertrain Control Module per Service Information.
Perform POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)
Page 1439 of 5267
P1594-CHARGING SYSTEM VOLTAGE TOO HIGH
For a complete wiring diagramRefer to Section 8W.
Page 1440 of 5267

When Monitored:
With the ignition key on and the engine speed greater than 0 RPM.
Set Condition:
When the PCM regulates the generator field and there are no detected field problems, but the voltage output
does not decrease.
Possible Causes
(K20) GENERATOR FIELD CONTROL CIRCUIT SHORTED TO GROUND
GENERATOR FIELD COIL SHORTED TO GROUND
BATTERY TEMPERATURE SENSOR
PCM
Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. (Refer to 9 - ENGINE -
DIAGNOSIS AND TESTING)
Diagnostic Test
1.CHARGING SYSTEM OPERATION
NOTE: Battery must be fully charged and be capable of passing a load test.
NOTE: Generator Belt tension and condition must be checked before continuing.
Ignition on, engine not running.
With the scan tool, read DTCs and the related Freeze Frame data then clear theDTCs.
With scan tool, actuate the Generator Field Driver.
With a 12-volt test light connected to ground, backprobe the (K20) Gen Field Control circuit in the back of Generator
Field harness connector.
Does the test light illuminate brightly and flash?
Ye s>>
Go To 2
No>>
Refer to the INTERMITTENT CONDITION Diagnostic Procedure.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)
2.(K20) GEN FIELD CONTROL CIRCUIT SHORTED TO GROUND
Turn the ignition off.
Disconnect the C2 PCM harness connector.
Disconnect the Generator Field Harness connector.
Carefully inspect the related connectors for corrosion or spread termi-
nals before continuing.
Measure the resistance between ground and the (K20) Generator Field
Driver circuit at the Generator Field harness connector.
Istheresistancebelow100ohms?
Ye s>>
Repair the short to ground in the (K20) Generator Field
Control circuit.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to
9 - ENGINE - STANDARD PROCEDURE)
No>>
Go To 3