Generator Test

The following procedure is outlined step-by-step using the starting and charging system tester (SA9154Z-A).

CAUTION: SAFETY GLASSES SHOULD BE WORN AND RINGS, WATCHES, AND ALL OTHER HAND JEWELRY SHOULD BE REMOVED.

1. Verify the fusible link between the starter and generator is good. Also verify connections are tightened to specification and clean. (Charging system light functional test will verify link is OK.)

IMPORTANT: If a fusible link is blown, don't just replace it. The most probable cause of a blown link is an internal generator failure. Verify that there is no external arcing or shorting of fusible link with other wires and/or components. If no problems are found, replace generator.

2. Turn system tester On. Connect large red tester cable to battery positive (+). Connect large black tester cable to battery negative (-). Place gray inductive current pick-up around battery positive (+) cable. Make sure that the arrow on the gray inductive current pick-up is pointing toward the starter motor solenoid.




3. Place the gray inductive current pick-up around the battery positive cable between the battery positive terminal and the starter motor solenoid connection. The easiest place to connect the inductive pick-up is next to the brake master cylinder. The battery positive cable runs under the master cylinder and is covered by a protective wire conduit. This conduit does not need to be removed for this test. On vehicles equipped with ABS brakes, pick-up can be placed between the ABS master cylinder and starter motor.

NOTE: Verify inductive current pickup is completely closed around cable.

4. Perform the Battery Test to verify a good battery. Refer to the BATTERY LOAD TEST procedure. Battery Load Test

NOTE: A flat battery will adversely affect the Charging System Test results. Perform Battery Test before performing the Charging System Test. Battery Load Test

5. Start vehicle and turn all accessories Off.
6. Follow the system tester prompts.
7. Press CHARGING SYSTEM TEST. The display should show the correct number of cylinders. To change the number of cylinders, simply press that number on the keypad.

Results
The tester will display the voltage and current output of the generator.

Voltage
^ With a good battery in the vehicle, the voltage output should be between 13 and 15.5v.

Current
^ Use the chart to determine minimum output current.

Diode Pattern
^ Always ignore this test.

If the generator does not pass the above voltage and current tests:
1. If output current is below 20A, verify charge warning telltale operation. Refer to the Generator Cause Complaint Chart.
2. If output current is above 20A but below the specified minimum current, verify gray amp. probe is properly installed and belt is in good condition. If both pass, replace the generator.

Generator Output

Generator Output:

The Generator Output chart shows the generators dependency on the electrical demand (load), generator temperature, and engine.

IMPORTANT: When testing a generator, the load, temperature and rpm must be considered to obtain the most accurate conclusion. When using the system tester or a carbon pile tester (carbon pile fully On), the load will be approximately maximum load.