GM Service Manual Online
For 1990-2009 cars only

Battery is Overcharged or Undercharged

Step

Action

Value(s)

Yes

No

1

  1. Disconnect the generator battery terminal.
  2. Disconnect the generator connector.
  3. Turn the ignition switch to the RUN position.
  4. Measure the voltage between terminal L (V6 VIN M) or terminal B (L4 VIN 4) and ground with DMM.

Is battery voltage measured?

--

Go to Step 2

Go to Step 3

2

Measure the voltage with DMM between terminal F (V6 VIN M) or terminal C (L4 VIN 4) and ground .

Is battery voltage measured?

--

Go to Step 4

Go to Step 5

3

  1. Inspect circuit 25, circuit 39, and the indicator bulb for an open.
  2. If OK, replace or exchange the instrument cluster. Refer to Instrument Panel and Gauges.

Is the repair complete?

--

System OK

--

4

Measure the voltage with DMM between terminal S (V6 VIN M) or terminal D (L4 VIN 4) and ground.

Is the battery voltage measured?

--

Go to Step 6

Go to Step 7

5

Repair open in fuse 4 or circuit 241.

Is the repair complete?

--

System OK

--

6

Measure the voltage between the BATT terminal and ground.

Is battery voltage measured?

--

Go to Step 8

Go to Step 9

7

Repair the open in circuit 2, circuit 1040, or inline GEN Fuse (L4 VIN 4).

Is the repair complete?

--

System OK

--

8

  1. Reconnect the generator connector.
  2. Turn all the accessories OFF.
  3. START the engine running.
  4. Measure the voltage between BATT terminal and ground.

Is the measured voltage less than or equal to the specified value?

16 volts

Go to Step 10

Go to Step 11

9

Repair the open in circuit 2.

Is the repair complete?

--

System OK

--

10

  1. Perform the generator load test. Refer to Battery Load Test .
  2. Perform a battery load test. Refer to Cranking System.

Is the repair complete?

--

System OK

--

11

Repair or replace the generator. Refer to Generator Replacement or Generator Replacement .

Is the repair complete?

--

System OK

--