GM Service Manual Online
For 1990-2009 cars only

Step

Action

Value(s)

Yes

No

1

  1. Disconnect the generator connector.
  2. Set the ignition switch to the RUN position.
  3. Attach a scan tool to the DLC.
  4. Clear any DTC.
  5. Select the following options:
  6. 5.1. Select MISC Tests.
    5.2. Select ENG Outputs.
    5.3. Select GEN L TERM.
  7. Command the generator ON.
  8. Measure the voltage from the generator connector terminal L to ground.

Is the measured voltage within the specified range?

9-14 V

Go to Step 2

Go to Step 6

2

Measure the voltage from the generator BATTERY terminal to ground.

Is the measured voltage within the specified range?

9-14 V

Go to Step 3

Go to Step 9

3

  1. Reconnect the generator connector.
  2. Turn all the accessories OFF.
  3. Run the engine at a fast idle.
  4. Measure the voltage across the battery.

Is the measured voltage within the specified range?

13-16 V

Go to Step 4

Go to Step 10

4

Load test the generator. Refer to Charging System Check .

Does the generator operate properly?

--

Go to Step 5

Go to Step 10

5

Replace the battery. Refer to Battery Replacement .

Is the repair complete?

--

System OK

--

6

Check for a poor connection or open in circuit 225.

Is there a poor connection or open in circuit 225?

--

Go to Step 7

Step 8

7

Repair the poor connection or open in circuit 225.

Is the repair complete?

--

System OK

--

8

Service the PCM. Refer to Powertrain Control Module Replacement/Programming in Engine Controls - 3.8L or Powertrain Control Module Replacement/Programming in Engine Controls - 3.1L.

Is the repair complete?

--

System OK

--

9

Repair the open in circuit 2 or the fusible link to the generator BATTERY terminal.

Is the repair complete?

--

System OK

--

10

Replace the generator. Refer to Generator Replacement or Generator Replacement .

Is the repair complete?

--

System OK

--