GM Service Manual Online
For 1990-2009 cars only

Step

Action

Value(s)

Yes

No

1

Was the charging system check performed?

--

Go to Step 2

Go to Charging System Check

2

Check the battery hydrometer.

Is the green dot visible in the hydrometer?

--

Go to Step 4

Go to Step 3

3

Diagnose the battery hydrometer. Refer to Battery Hydrometer Displays Dark or Yellow Dot .

Is the diagnosis complete?

--

Go to Step 21

--

4

Perform the battery load test. Refer to Battery Load Test .

Did the battery pass the load test?

--

Go to Step 6

Go to Step 5

5

Replace the battery. Refer to Battery Replacement .

Is the repair complete?

--

Go to Step 21

--

6

Check the generator. Refer to Generator Not Operating Properly .

Does the generator operate properly?

--

Go to Step 7

Go to Step 20

7

  1. Disconnect the generator connector.
  2. Turn the ignition switch to ON.
  3. Using a DMM set to DC volts, measure the voltage from the generator connector terminal B to ground.

Is the measured voltage above the specified value?

10V

Go to Step 8

Go to Step 17

8

Check CKT 225 (RED) and CKT 23 (GRY) for an intermittent short to ground or open condition.

Are the circuits OK?

--

Go to Step 21

Go to Step 9

9

Repair CKT 225 (RED) or CKT 23 (GRY).

Is the circuit repair complete?

--

Go to Step 21

--

10

  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 terminals.

Is the measured voltage within the specified range?

13-16V

Go to Step 21

Go to Step 11

11

  1. Keep the engine running at fast idle.
  2. Disconnect the battery thermistor connector, located near the battery.
  3. Using a DMM set to DC volts scale, measure the voltage across the battery terminals.

Is the voltage in the specified range?

13-16V

Go to Step 12

Go to Step 17

12

  1. Turn the ignition switch to OFF.
  2. Using a DMM set to DC volts scale, measure the voltage at battery thermistor connector terminal A (body harness side).

Is the measured voltage in the specified range?

10-15V

Go to Step 14

Go to Step 13

13

  1. Check the DIM fuse for an open.
  2. If the fuse is open, repair CKT 3340 (ORN) short to ground.
  3. If the fuse is OK, repair open or high resistance in CKT 3340 (ORN).

Is the circuit repair complete?

--

Go to Step 21

--

14

  1. Disconnect the generator connector.
  2. Connect a fused jumper from generator harness connector terminal D to ground.
  3. Connect a DMM set to ohms scale between the battery thermistor connector terminal B (body harness side) and ground.

Is the measured resistance in the specified range?

Less than 5ohms

Go to Step 16

Go to Step 15

15

Repair high resistance or open in CKT 725 (LT BLU).

Is the circuit repair complete?

--

Go to Step 21

--

16

  1. Check the battery thermistor connector for poor terminal contact.
  2. If OK, replace the battery thermistor.

Is the replacement complete?

--

Go to Step 21

--

17

Check for an open or short to ground in CKT 225 (RED).

Is the circuit OK?

--

Go to Step 19

Go to Step 18

18

Repair CKT 225 (RED).

Is the circuit repair complete?

--

Go to Step 21

--

19

  1. Check the powertrain control module (PCM) connector C1 for poor terminal contact.
  2. If OK, replace the PCM. Refer to Powertrain Control Module Replacement in Engine Controls -- 4.6L.

Is the replacement complete?

--

Go to Step 21

--

20

Replace the generator. Refer to Generator Replacement .

Is the replacement complete?

--

Go to Step 21

--

21

Repeat the Charging System Check. Refer to Charging System Check .

Is the system check complete?

--

System OK

--