Important:  Automotive generators produce a certain amount of low level sound during normal operation. This sound is caused by a combination of mechanical and electrical/magnetic conditions in the generator. Typically, the sound level will be higher during periods of high output demand on the generator. Objectionable noise from a generator may be caused by conditions causing normal sound to be transmitted directly to the passenger compartment, by mounting problems, or by internal generator conditions. The following can cause objectionable noise:

Tools Required

J 39200 Digital Multimeter (DMM)

Important: If a charging system tester is used, ensure that the inductive lead is installed properly in order to obtain an accurate amperage reading.

If an automated charging system tester is used, follow the manufacturers instructions for proper connection and operation of the tester.

If an automated charging system tester is not available, perform the following steps:

1. Install the ammeter lead to the generator B+ lead. If an in-line ammeter is used, perform the following steps:

1.1.	Remove the battery negative cable from the battery. Refer to Battery Negative Cable Disconnection and Connection .

1.2.	Remove the generator B+ lead from the generator B+ terminal.

Important: Insulate the ammeter connections in order to prevent a short.

1.3.	Install the ammeter between the generator output B+ terminal and the engine wiring harness.

1.4.	Install the battery negative cable to the battery. Refer to Battery Negative Cable Disconnection and Connection .

2. Turn the carbon pile (load tester) off.
3. Connect the carbon pile (load tester) across the battery terminals.
4. Start the engine.
5. Raise the engine speed to 2000 RPM.
6. Turn the carbon pile (load tester) on.
7. Adjust the load to the proper level according to the generator (RPO code).

•	If the vehicle is equipped with the Bosch KCB2 generator (K68), adjust the carbon pile load to 73 amperes.

•	If the vehicle is equipped with the Bosch NCB1 generator (KG9), adjust the carbon pile load to 85 amperes.

-	If the load test amperage value cannot be obtained and the voltage reading falls below 13.0, replace the generator. Refer to Generator Replacement .

-	If the load test amperage value cannot be obtained and the voltage reading is between the minimum and the maximum, a carbon pile (load tester) failure is the cause of the problem.

8. With the carbon pile load still applied, use the J 39200 to inspect the battery voltage. If the voltage is below 13.0 or above 15.5, replace the generator. Refer to Generator Replacement .