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P0622-GENERATOR FIELD NOT SWITCHING PROPERLY
For a complete wiring diagramRefer to Section 8W.
Page 1314 of 5267

When Monitored:
With the ignition key on and the engine running.
Set Condition:
When the PCM tries to regulate the generator field with no result during monitoring.
Possible Causes
(K125) GEN FIELD SOURCE CIRCUIT OPEN
(K20) GEN FIELD CONTROL CIRCUIT OPEN
(K20) GEN FIELD CONTROL CIRCUIT SHORTED TO GROUND
GENERATOR
PCM
Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. (Refer to 9 - ENGINE -
DIAGNOSIS AND TESTING)
1.GENERATOR FIELD PERFORMANCE
Ignition on, engine not running.
Record all DTCs and the related Freeze Frame data.
Turn the ignition off.
Disconnect the Generator harness connector.
Ignition on, engine not running.
Using a 12-volt test light connected to 12-volts, probe the (K20) Gen
Field Control circuit at the Generator harness connector.
With the scan tool, actuate the Generator Field Driver.
Does the test light blink?
Ye s>>
Refer to the INTERMITTENT CONDITION Diagnostic Pro-
cedure.
Perform POWERTRAIN VERIFICATION TEST. (Refer to 9 -
ENGINE - STANDARD PROCEDURE)
No>>
Go To 2
2.(K125) GEN FIELD SOURCE CIRCUIT OPEN
Turn the ignition off.
Disconnect the C2 and C3 PCM harness connectors.
Carefully inspect all connectors for corrosion or spread terminals before
continuing.
Measure the resistance of the (K125) Generator Field Source circuit
from the Generator harness connector to the C3 PCM harness connec-
tor.
Is the resistance below 5.0 ohms?
Ye s>>
Go To 3
No>>
Repair the open in the (K125) Gen Field Source circuit.
Perform POWERTRAIN VERIFICATION TEST. (Refer to 9 -
ENGINE - STANDARD PROCEDURE)
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3.(K20) GEN FIELD CONTROL CIRCUIT OPEN
Measure the resistance of the (K20) Generator Field Control circuit from
the Generator Field harness connector to the C2 PCM harness connec-
tor.
Is the resistance below 5.0 ohms?
Ye s>>
Go To 4
No>>
Repair the open in the (K20) Gen Field Control circuit.
Perform POWERTRAIN VERIFICATION TEST. (Refer to 9 -
ENGINE - STANDARD PROCEDURE)
4.(K20) GEN FIELD CONTROL CIRCUIT SHORTED TO GROUND
Measure the resistance between ground and the (K20) Generator Field
Control circuit in the Generator harness connector.
Istheresistancebelow100ohms?
Ye s>>
Repair the short to ground in the (K20) Gen Field Control
circuit.
Perform POWERTRAIN VERIFICATION TEST. (Refer to 9 -
ENGINE - STANDARD PROCEDURE)
No>>
Go To 5
5.GENERATOR
Measure resistance across the Generator Field Terminals at the Generator.
Is the resistance between 0.5 of and ohm and 15 ohms?
Ye s>>
Go To 6
No>>
Repair the Generator as necessary.
Perform POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)
Page 1316 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)
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P0645-A/C CLUTCH RELAY CIRCUIT
For a complete wiring diagramRefer to Section 8W.
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When Monitored:
With the ignition on. Battery voltage greater than 10 volts. A/C Switch on.
Set Condition:
An open or shorted condition is detected in the A/C clutch relay control circuit. One Trip Fault. Three good trips
to turn off the MIL.
Possible Causes
INTERNAL FUSED IGNITION SWITCH OUTPUT CIRCUIT
INTERNAL FUSED B+ CIRCUIT
(C13) A/C CLUTCH RELAY CONTROL CIRCUIT OPEN
(C13) A/C CLUTCH RELAY CONTROL CIRCUIT SHORTED TO GROUND
A/CCLUTCHRELAY
PCM
Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. (Refer to 9 - ENGINE -
DIAGNOSIS AND TESTING).
Diagnostic Test
1.A/C CLUTCH RELAY OPERATION
Ignition on, engine not running.
With a scan tool, actuate the A/C Clutch Relay.
Is the A/C Clutch Relay operating?
Ye s>>
Refer to the INTERMITTENT CONDITION Diagnostic Procedure.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)
No>>
Go To 2
2.A/C CLUTCH RELAY RESISTANCE
Turn the ignition off.
Remove the A/C Clutch Relay from the IPM.
Measure the resistance of the A/C Clutch Relay Coil.
Is the resistance between 60 to 80 ohms?
Ye s>>
Go To 3
No>>
Replace the A/C Clutch Relay.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)
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3.INTERNAL FUSED IGNITION SWITCH OUTPUT CIRCUIT AND FUSED B+ CIRCUIT
Ignition on, engine not running.
Using a 12-volt test light connected to ground, probe the Internal Fused
Ignition Switch Output circuit and the Fused B+ circuit in the connection.
Does the test light illuminate brightly?
Ye s>>
Go To 4
No>>
Repair the open or short to ground in the Fused Ignition
Switch Output circuit or the Fused B+ circuit. Check and
replace any open fuses.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to
9 - ENGINE - STANDARD PROCEDURE)
4.(C13) A/C CLUTCH RELAY CONTROL CIRCUIT OPEN
Turn the ignition off.
Disconnect the C3 PCM harness connector.
Measure the resistance of the (C13) A/C Clutch Relay Control circuit from the relay connection to the PCM harness
connector.
Is the resistance below 5.0 ohms?
Ye s>>
Go To 5
No>>
Repair the open in the (C13) A/C Clutch Relay Control circuit.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)
5.(C13) A/C CLUTCH RELAY CONTROL CIRCUIT SHORTED TO GROUND
Measure the resistance between ground and the (C13) A/C Clutch
Relay Control circuit at the IPM.
Is the resistance below 5.0 ohms?
Ye s>>
Repair the short to ground in the (C13) A/C Relay Clutch
Control circuit.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to
9 - ENGINE - STANDARD PROCEDURE)
No>>
Go To 6
Page 1320 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.
Were there any problems found?
Ye s>>
Repair as necessary.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)
No>>
Replace and program the Powertrain Control Module per Service Information.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)