GM Service Manual Online
For 1990-2009 cars only

Battery Is Undercharged or Overcharged LG4 Engine

Step

Action

Value(s)

Yes

No

1

  1. Disconnect the generator connector.
  2. Place the ignition switch in the RUN position.
  3. Connect a voltmeter from CKT 5 (BRN) at the generator connector to chassis ground.
  4. Observe the reading on the voltmeter.

Does a battery voltage exist?

--

Go to Step 5

Go to Step 2

2

Inspect the condition of the indicator bulb.

Is the indicator bulb in proper condition?

--

Go to Step 4

Go to Step 3

3

Replace the indicator bulb.

Is the battery still undercharged or overcharged?

--

Go to Step 4

System OK

4

Locate and repair the open in the BRN wire between the instrument cluster and the generator.

Is the battery still undercharged or overcharged?

--

Go to Step 5

System OK

5

Connect a J 39200 from battery terminal 1 (RED) at the generator connector to chassis ground.

Does the voltmeter read a battery voltage?

--

Go to Step 7

Go to Step 6

6

Locate and repair the open in CKT 1 (RED) between the generator and the MaxiFuse® Block.

Is the battery still undercharged or overcharged?

--

Go to Step 7

System OK

7

  1. Reconnect the generator connector.
  2. Turn off all accessories.

  3. Run the engine at a fast idle.
  4. Connect a J 39200 from battery terminal 1 (RED) at the generator to chassis ground.

Does the voltmeter give a reading within the specified range?

13-16 V

Go to Step 8

Go to Step 9

8

Perform a battery load test. Refer to Charging System Check .

Is the battery still undercharged or overcharged?

--

Go to Step 9

System OK

9

Perform a generator bench test. Refer to Charging System Check

Is the generator in need of repair or replacement?

--

Go to Step 10

Go to Step 11

10

Repair or replace the generator. Refer to Generator Replacement .

Is the battery still undercharged or overcharged?

--

--

System OK

11

Perform a battery load test. Refer to Charging System Check

Is the battery still undercharged or overcharged?

--

--

System OK