*CHECKING THE CHARGING SYSTEM OPERATION

For a complete wiring diagram Refer to Section 8W.

Diagnostic Test

1.GENERATOR FULL FIELD TEST

NOTE: Diagnose and repair any generator sense or field control circuit DTCs before proceeding with this test.

WARNING: When the engine is operating, do not stand in direct line with the fan. Do not put your hands near the pulleys, belts, or fan. Do not wear loose clothing. Failure to follow these instructions can result in personal injury or death.

NOTE: With the engine running, the difference between the system (battery) voltage and the generator sense voltage should be below .2 volts.

NOTE: With the generator field fully actuated, the system (battery) voltage should be above 14.0 volts.

NOTE: With the generator field actuated off, the system (battery) voltage should be below 13.0 volts, and eventually drop as battery load is increased.

Did the system voltage change as described above during the Generator Full Field test?

Yes

Test complete.

Go to 2

2.CHARGING SYSTEM INSPECTION

Were any problems found?

Yes

Repair as necessary.

Go to 3

3.BATTERY POSITIVE (+) CIRCUIT HIGH RESISTANCE

NOTE: Make sure all testing equipment and cables are clear of any engine parts before starting the engine.

Is the voltage below 0.4 volts?

Yes

Go to4

Repair the battery positive (+) circuit between the generator and battery for high resistance.
Perform the PCM Verification Test. (Refer to 9 - ENGINE - STANDARD PROCEDURE)

4.GENERATOR CASE GROUND HIGH RESISTANCE

NOTE: Make sure all testing equipment and cables are clear of any engine parts before starting the engine.

Is the voltage below 0.1 volt?

Yes

Go to5

Repair the Generator Case ground for high resistance.
Perform the PCM Verification Test. (Refer to 9 - ENGINE - STANDARD PROCEDURE)

5.(A109) FUSED B(+) CIRCUIT HIGH RESISTANCE

CAUTION: Do not probe the PCM harness connectors. Probing the PCM harness connectors will damage the PCM terminals resulting in poor terminal to pin connection. Install Miller Special Tool #8815 along with the #8815-1 to perform the diagnosis.

Is the voltage below 0.5 volts?

Yes

Go to 6

Repair the (A109) Fused B(+) circuit(s) for high resistance.
Perform the PCM Verification Test. (Refer to 9 - ENGINE - STANDARD PROCEDURE)

6.(A804) GENERATOR SENSE CIRCUIT HIGH RESISTANCE

Is the voltage below 0.5 volts?

Yes

Go to 7

Repair the (A804) Generator Sense circuit for high resistance.
Perform the PCM Verification Test. (Refer to 9 - ENGINE - STANDARD PROCEDURE)

7.(K20) GEN FIELD CONTROL CIRCUIT HIGH RESISTANCE

Is the voltage below 0.5 volts?

Yes

Go to 8

Repair the (K20) Gen Field Control circuit for high resistance.
Perform the PCM Verification Test. (Refer to 9 - ENGINE - STANDARD PROCEDURE)

8.GENERATOR

NOTE: The test light should toggle on and off with the actuation.

NOTE: If a DTC is active, the actuation test may not be allowed by the PCM. If may be necessary to clear DTCs before starting the actuation.

Does the test light illuminate on and off with the actuation?

Yes

Replace the Generator in accordance with the Service Information.
Perform the PCM Verification Test. (Refer to 9 - ENGINE - STANDARD PROCEDURE)

Go to9

9.(K20) GEN FIELD CONTROL CIRCUIT SHORTED TO VOLTAGE

Is there any voltage present?

Yes

Repair the (K20) Gen Field Control circuit for a short to voltage.
Perform the PCM Verification Test. (Refer to 9 - ENGINE - STANDARD PROCEDURE)

Go to 10

10.(K20) GEN FIELD CONTROL CIRCUIT SHORTED TO GROUND

Is the resistance below 100 ohms?

Yes

Repair the (K20) Gen Field Control circuit for a short to ground.
Perform the PCM Verification Test. (Refer to 9 - ENGINE - STANDARD PROCEDURE)

Go to11

11.(K20) GEN FIELD CONTROL CIRCUIT OPEN OR HIGH RESISTANCE

CAUTION: Do not probe the PCM harness connectors. Probing the PCM harness connectors will damage the PCM terminals, resulting in poor terminal to pin connection. Install Miller Special Tool #8815 to perform diagnosis.

Is the resistance below 5.0 ohms?

Yes

Go to12

Repair the (K20) Gen Field Control circuit for an open circuit or high resistance.
Perform the PCM Verification Test. (Refer to 9 - ENGINE - STANDARD PROCEDURE)

12.CHECKING THE PCM POWER AND GROUND CIRCUITS

Were any problems found?

Yes

Repair the PCM power and ground circuit(s) as necessary.
Perform the PCM Verification Test. (Refer to 9 - ENGINE - STANDARD PROCEDURE)

Go to 13

13.POWERTRAIN CONTROL MODULE (PCM)

Were any problems found?

Yes

Repair as necessary.
Perform the PCM Verification Test. (Refer to 9 - ENGINE - STANDARD PROCEDURE)

Replace and program the Powertrain Control Module (PCM) in accordance with the Service Information.
Perform the PCM Verification Test. (Refer to 9 - ENGINE - STANDARD PROCEDURE)