Did you perform the Diagnostic System Check - Vehicle?

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Go to Step 2

Go to Diagnostic System Check - Vehicle

Important: The battery must be above a 70 percent state of charge. Refer to Battery Charging .

Did you perform the Battery Inspection Test?

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Go to Step 3

Go to Battery Inspection/Test

1. Install a scan tool.
2. Start the engine.
3. With a scan tool, command the GEN-L Terminal OFF and ON.
4. Observe the Ignition 1 Signal parameter.

Does the voltage change with each command?

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Go to Step 4

Go to Step 8

1. Turn ON the following accessories:

•	Headlights (high beams)

•	Air Conditioning (A/C) on Max

•	Blower fan (on high)

•	Heated seats (if equipped)

2. With a scan tool, observe the Ignition 1 Signal parameter in the engine control module (ECM) data list.
3. Increase engine speed to 2,500 RPM.

Is the voltage within the specified value?

12-15.5 V

Go to Step 5

Go to Step 6

1. Turn OFF all accessories.
2. Turn OFF the ignition.

Caution: Make sure that the load is completely turned off before connecting or disconnecting a carbon pile load tester to the battery. Otherwise, sparking could ignite battery gasses which are extremely flammable and may explode violently.

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. With a scan tool, command the GEN-L Terminal ON.
7. Increase engine speed to 2,500 RPM.
8. 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 ?

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Generator OK

Go to Step 7

Is the voltage measured greater than the specified value?

15.5 V

Go to Step 12

Go to Step 7

1. Leave the vehicle accessories ON or maintain load test value.
2. Maintain engine speed at 2,500 RPM.
3. Measure the voltage of the battery.
4. Measure the voltage between the generator output terminal and the generator metal housing.

Is the voltage measured at the generator within the specified value of the battery voltage?

0.2 V

Go to Step 14

Go to Step 9

1. Turn ON the ignition, with the engine OFF.
2. Disconnect the generator harness connector.
3. Measure the voltage between the generator turn on signal circuit and ground.
4. With a scan tool, command the GEN-L Terminal ON and OFF.

Does the voltage measure greater than the first value ON and near the second value OFF?

4.7 V

0 V

Go to Step 14

Go to Step 11

1. Maintain the engine speed at 2,500 RPM and continue to operate the generator at the load test value.
2. Measure the voltage drop from the battery negative terminal to the metal housing of the generator. Refer to Circuit Testing and Wiring Repairs.

Is the voltage measured less than the specified value?

0.5 V

Go to Step 10

Go to Step 15

1. Maintain the engine speed at 2,500 RPM and continue to operate the generator at the load test value.
2. Measure the voltage drop from the output terminal of the generator to the positive terminal on the battery. Refer to Circuit Testing and Wiring Repairs.

Is the voltage measured less than the specified value?

0.2 V

Go to Step 14

Go to Step 16

Test the generator turn on signal circuit for a short or an open. 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 13

Test the generator battery voltage sense circuit, if equipped, 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 14

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

Did you find and correct the condition?

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Go to Step 19

Go to Step 17

Inspect for poor connections at the generator. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs.

Did you find and correct the condition?

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Go to Step 19

Go to Step 18

Repair the high resistance or open in the ground circuit of the generator. Refer to Wiring Repairs.

Did you complete the repair?

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Go to Step 19

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Repair the high resistance or open in the generator output circuit. Refer to Wiring Repairs.

Did you complete the repair?

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Go to Step 19

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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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Generator OK

Go to Step 2