Did you perform the Diagnostic System Check - Vehicle?

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Go to Step 2

Go to Diagnostic System Check - Vehicle

With the ignition OFF, install the J 42000 and verify the condition of the battery.

Is the battery sufficiently charged for testing?

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Go to Step 3

Go to Battery Inspection/Test

1. Disconnect the J 42000 .
2. Connect the Sun Vat 40 tester or equivalent carbon pile tester to the battery.
3. Turn the ignition to the OFF/LOCK position.
4. Observe and record the battery voltage reading at the battery terminals on the carbon pile tester.
5. Start the engine and observe the system voltage reading on the tester.

Does the voltage increase from the first specified (engine OFF) to the second (engine ON) specified range?

Engine Off = B+

Engine On = 13.9-15.5 V

Go to Step 4

Go to Step 6

1. Turn ON the following accessories:

•	Headlights - HI beams

•	A/C on Max

•	Blower Fan - On high

•	Rear window defogger

•	Heated seats, if equipped

2. Maintain engine speed at 2,500 RPM.

Is voltage still within the specified value?

13.9-15.5 V

Go to Step 5

Go to Step 6

1. Turn OFF all accessories.
2. Turn OFF the ignition.
3. Connect a carbon pile tester to the vehicle.

Important: When measuring generator output current, be sure the inductive probe encircles the generator output wire.

4. Connect an inductive ammeter probe to the output circuit of the generator.
5. Start the engine.
6. Increase engine speed to 2,500 RPM.
7. Adjust the carbon pile as necessary in order to obtain the maximum current output.

Is the generator output greater than or equal to the load test value as specified in Generator Usage .

System OK

Go to Step 10

1. Turn the engine OFF.
2. Disconnect the generator harness connector.
3. Turn the ignition to the ON position.
4. Using a DMM, measure the voltage on the L-terminal circuit.

Is the voltage greater than the specified value?

0 V

Go to Step 11

Go to Step 7

1. Turn the engine OFF.
2. Start the engine and check the voltage on the L-terminal.

Is the voltage within the specified value?

5 V

Go to Step 8

Go to Step 12

1. Turn the engine OFF.
2. Turn the ignition switch to ON position.
3. Using the scan tool, observe the duty cycle in the F-terminal signal parameter.

Does the scan tool display the indicated value?

0 Percent

Go to Step 9

Go to Step 13

Connect a test lamp to B+ and repeatedly touch the F-terminal at the generator harness connector while monitoring the GEN-F terminal signal parameter on the scan tool.

Does the scan tool indicate that the generator PWM is above the specified range?

90 Percent

Go to Step 10

Go to Step 14

1. Turn the engine OFF.
2. Inspect the generator B+ output terminal at the generator for an open or high resistance. Refer to Circuit Testing and Wiring Repairs .

Did you find and correct the condition?

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Go to Step 19

Go to Step 15

Test the L-terminal circuit for a short to voltage. Refer to Circuit Testing and Wiring Repairs .

Did you find and correct the condition?

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Go to Step 19

Go to Step 16

Test the L-terminal circuit for open or short to ground. Refer to Circuit Testing and Wiring Repairs .

Did you find and correct the condition?

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Go to Step 19

Go to Step 16

Test the GEN-F terminal for a short to voltage. Refer to Circuit Testing and Wiring Repairs .

Did you find and correct the condition?

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Go to Step 19

Go to Step 16

Test the GEN-F terminal circuit for an open or short to ground. Refer to Circuit Testing and Wiring Repairs .

Did you find and correct the condition?

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Go to Step 19

Go to Step 16

Inspect for poor connections at the generator. Refer to Circuit Testing and Wiring Repairs .

Did you find and correct the condition?

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Go to Step 19

Go to Step 18

Inspect for poor connections at the harness connector of the engine control module (ECM). Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs .

Did you find and correct the condition?

Go to Step 19

Go to Step 17

Important: The replacement ECM must be programmed.

Replace the ECM. Refer to Control Module References for replacement, setup, and programming.

Did you complete the replacement?

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Go to Step 19

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Replace the generator. Refer to Generator Replacement .

Did you complete the replacement?

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Go to Step 19

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Operate the vehicle in order to verify the repair.

Did you correct the condition?

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System OK

Go to Step 2