GM Service Manual Online
For 1990-2009 cars only

Tools Required

J 41450-B Universal CS Generator Test Harness

Test Description

The step below refers to the test steps in the diagnostic table.

  1. If the test has shown the generator to be OK, however the condition remains, test the PCM or its control circuit to the generator.

Step

Action

Values

Yes

No

1

Did you perform the Diagnostic System Check for Engine Electrical?

--

Go to Step 2

Go to Diagnostic System Check - Engine Electrical

2

Start the engine, observe the charge indicator on the instrument cluster (IPC) or message in the driver information center (DIC).

Does the charge indicator illuminate or the DIC display a charging system message?

--

Go to Step 3

Go to Testing for Intermittent Conditions and Poor Connections in Wiring Systems

3

Important: The green POWER lamp of the tester should remain illuminated while the tester is being used.

  1. Turn OFF the ignition.
  2. Connect the red lead of the J 41450-B to the generator output terminal.
  3. Connect the black lead of the J 41450-B to the metal generator housing.

Does the green POWER lamp on the tester illuminate?

--

Go to Step 6

Go to Step 4

4

Measure the voltage from the output terminal of the generator to the generator metal housing.

Does the voltage measure equal to the specified value?

B +

Go to Step 14

Go to Step 5

5

Measure the voltage from the output terminal of the generator to the battery negative terminal.

Does the voltage measure equal to the specified value?

B +

Go to Step 12

Go to Step 11

6

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.

  1. Connect a carbon pile tester to the vehicle.
  2. Important: Be sure all of generator output circuit wires pass through the inductive probe.

  3. Connect an inductive ammeter to the output circuit of the generator.
  4. Disconnect the generator harness connector.
  5. Locate the matching harness connector on the J 41450-B and connect it to the generator.

Does the red DIAGNOSTIC lamp on the tester light?

--

Go to Step 7

Go to Step 13

7

  1. Start the engine and allow it to idle for 30 seconds.
  2. Increase the engine speed to 2,500 RPM.

Does the red DIAGNOSTIC lamp on the tester illuminate?

--

Go to Step 15

Go to Step 8

8

  1. Maintain the engine speed at 2,500 RPM.
  2. Important: If the generator is not capable of producing the Load Test amps, operate the generator at it's maximum possible output.

  3. Turn ON the load of the carbon pile tester and increase the load until the generator output is greater than or equal to the load test value given in Generator Usage .

Does the red DIAGNOSTIC lamp on the tester illuminate?

--

Go to Step 15

Go to Step 9

9

  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 in Wiring Systems.

Does the voltage measure greater than the specified value?

0.5 V

Go to Step 11

Go to Step 10

10

  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 in Wiring Systems.

Does the voltage measure greater than the specified value?

0.5 V

Go to Step 12

Go to Step 16

11

Repair the high resistance or an open in the output circuit of the generator. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you complete the repair?

--

Go to Step 16

--

12

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

Did you complete the repair?

--

Go to Step 16

--

13

  1. Disconnect the J 41450-B tester harness connector from the generator, but leave the alligator clips connected so that the green POWER lamp remains illuminated.
  2. Connect a jumper lead, with an in-line 100-ohm resistor between the J 41450-B tester harness connector terminal B and a good ground. Refer to Engine Electrical Connector End Views .

Does the red DIAGNOSTIC lamp illuminate?

--

Go to Step 15

Go to Step 14

14

There is a problem with the J 41450-B . Refer to the manufacturers instructions on how to test the J 41450-B for proper operation.

Has the J 41450-B tester been replaced?

--

Go to Step 3

--

15

Replace the generator. Refer to Generator Replacement .

Did you complete the replacement?

--

Go to Step 16

--

16

Operate the vehicle in order to verify the repair.

Did you correct the condition?

--

System OK

Go to Step 2