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Possible Causes
GENERATOR BELT CONDITION
RESISTANCE IN THE BATTERY POSITIVE CIRCUIT
(K125) GENERATOR FIELD SOURCE CIRCUIT OPEN
GENERATOR FIELD COIL HIGH RESISTANCE
(K20) GEN FIELD CONTROL CIRCUIT OPEN
RESISTANCE IN THE GENERATOR GROUND
PCM
Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. (Refer to 9 - ENGINE -
DIAGNOSIS AND TESTING)
Diagnostic Test
1.TARGET CHARGING DIFFERS FROM ACTUAL CHARGING BY 1 VOLT
NOTE: Verify that the Battery is able to pass a load test before continuing.
Ignition on, engine not running.
With the scan tool, read the Battery voltage and record the results.
Measure Battery voltage between the Battery Positive and Negative Terminals and record the results.
Compare the two voltage readings.
Is the voltage difference less than one volt?
Ye s>>
Go To 2
No>>
Go To 8
2.RESISTANCE IN THE BATTERY POSITIVE CIRCUIT
Ignition on, engine not running.
Measure the voltage between the Generator B+ Terminal and the Battery+ Post.
CAUTION: Make sure all wires are clear of the engine’s moving parts.
Start the engine.
Is the voltage above 0.4 of a volt?
Ye s>>
Repair the excessive resistance in the Battery Positive circuit between the Generator and Battery.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)
No>>
Go To 3
3.(K125) GEN FIELD SOURCE CIRCUIT OPEN
Ignition on, engine not running.
Record all DTCs and freeze frame data, now erase Codes.
Carefully inspect all connectors for corrosion or spread terminals before continuing.
With the scan tool, actuate the Generator Field Driver.
Measure the voltage of the (K125) Generator Field Source circuit by backprobing the back of Generator Field har-
ness connector.
Is the voltage above 10.0 volts?
Ye s>>
Go To 4
No>>
Repair the (K125) Generator Field Source circuit for an open or short to ground.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)
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4.RESISTANCE IN THE GENERATOR GROUND
Start the engine.
Warm the engine to operating temperature.
CAUTION: Make sure all wires are clear of the engine’s moving parts.
Measure the voltage between the Generator case and Battery Negative Post.
Is the voltage above 0.1 of a volt?
Ye s>>
Repair the excessive resistance in the Generator Ground circuit between the Generator Case and Bat-
tery Ground side.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)
No>>
Go To 5
5.GENERATOR FIELD COIL HIGH RESISTANCE
Turn the ignition off.
Disconnect the Generator Field harness connector at back of the Generator.
Measure resistance across the Generator Field Terminals at the Generator.
Is the resistance above 15 ohms?
Ye s>>
Replace or repair the Generator as necessary.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)
No>>
Go To 6
6.(K20) GEN FIELD CONTROL CIRCUIT OPEN
Disconnect the C3 PCM harness connector.
Measure the resistance of the (K20) Generator Field Driver circuit
between the C3 PCM harness connector and the Generator harness
connector.
Is the resistance below 5.0 ohms?
Ye s>>
Go To 7
No>>
Repair the open in the (K20) Gen Field Control circuit.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to
9 - ENGINE - STANDARD PROCEDURE)
7.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
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Replace and program the Powertrain Control Module per Service Information.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)
8.GENERATOR BELT CONDITION
Turn the ignition off.
NOTE: Battery condition must be verified prior to this test.
Inspect the Generator Belt tension and condition.
Is the Generator Belt OK?
Ye s>>
Go To 9
No>>
Repair as necessary.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)
9.ACTIVE DTC SET
Start the engine.
Turn on all accessories.
Raise engine speed to 2000 RPM for 30 seconds then return to idle.
With the scan tool, read DTCs.
Are there any
Charging SystemTrouble Codes?
Ye s>>
Refer to DTC list for the related Charging DTCs.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)
No>>
Go To 10
10.WIRE HARNESS INSPECTION
Ignition on, engine not running.
With the scan tool, actuate the Generator Field Driver.
Using a 12-volt test light, backprobe the Generator Field Driver Terminalat the back of the Generator.
NOTE: The test light should blink On and Off every 1.4 seconds.
While monitoring the 12-volt test light, wiggle the Field Terminals back to the PCM and ASD Relay.
Was there any interruption in the normal cycle of the test light?
Ye s>>
Repair the wire or connector where the wiggling interrupted the voltage cycle.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)
No>>
Te s t C o m p l e t e .
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*CHECKING RADIATOR FAN OPERATION
For a complete wiring diagramRefer to Section 8W.
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Possible Causes
HARNESS INSPECTION
HYDRAULIC FAN
Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. (Refer to 9 - ENGINE -
DIAGNOSIS AND TESTING)
Diagnostic Test
1.FAN OPERATION
Ignition on, engine not running.
With the scan tool select Engine Test, Systems Test, and Hydraulic Fan Solenoid Test.
Actuate the Hydraulic Fan Solenoid Test.
Does the fan operate properly?
Ye s>>
Te s t C o m p l e t e .
No>>
Go To 2
2.HARNESS INSPECTION
Turn the ignition off.
Check to see if the fan wire harness is properly connected at the upper rightcorner of the fan shroud.
Check to see if the fan wire harness is properly connected at the fan solenoidonthefanmotor.
Check the harness for continuity from the Hydraulic Fan Relay to the solenoid.
Inspect connector terminals for proper pin fit and corrosion.
Inspect the related fuse and relay.
Were any problems found?
Ye s>>
Repair any defective wire harness concerns.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)
No>>
Go To 3
3.HYDRAULIC FAN
Turn the ignition off.
Inspect the hydraulic circuit for leaks and repair as necessary.
Were any problems found?
Ye s>>
Repair the Hydraulic leaks and/or replace the Hydraulic Fan assembly.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)
No>>
Te s t C o m p l e t e .
Page 1478 of 5267
*CHECKING THE PCM POWER AND GROUNDS
For a complete wiring diagramRefer to Section 8W.
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Possible Causes
(A919) PCM FUSED B+ CIRCUIT
(F202) PCM FUSED IGNITION SWITCH OUTPUT CIRCUIT
(Z130) AND (Z131) PCM GROUND CIRCUITS
Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. (Refer to 9 - ENGINE -
DIAGNOSIS AND TESTING)
Diagnostic Test
1.(A919) PCM FUSED B+ CIRCUIT
Turn the ignition off.
Disconnect the PCM harness connectors.
Using a 12-volt test light connected to ground, probe the (A919) PCM
Fused B+ circuit in the C1 PCM harness connector.
Does the test light illuminate brightly?
Ye s>>
Go To 2
No>>
Repair the open in the (A1919) Fused B+ circuit. Inspect
the related fuse and repair as necessary.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to
9 - ENGINE - STANDARD PROCEDURE)
2.(F202) PCM FUSED IGNITION SWITCH OUTPUT CIRCUIT
Ignition on, engine not running.
Using a 12-volt test light connected to ground, probe the (F202) PCM
Fused Ignition Switch Output circuit in the C1 PCM harness connector.
Does the test light illuminate brightly?
Ye s>>
Go To 3
No>>
Repair the open in the (F202) Fused Ignition Switch Output
circuit.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to
9 - ENGINE - STANDARD PROCEDURE)
Page 1480 of 5267
3.(Z130) AND (Z131) PCM GROUND CIRCUITS
Turn the ignition off.
Using a 12-volt test light connected to battery voltage, probe the (Z130)
and (Z131) PCM ground circuits in the C1 PCM harness connector.
Does the test light illuminate brightly?
Ye s>>
Te s t C o m p l e t e .
No>>
Repair the open in the (Z130) and (Z131) PCM ground cir-
cuits.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to
9 - ENGINE - STANDARD PROCEDURE)