For 1990-2009 cars

Step | Action | Value(s) | Yes | No
--- | --- | --- | --- | ---
1 | Did you perform the Charging System Check ? | -- | Go to Step 2 | Go to Charging System Check
2 |

1. Connect a scan tool to the data link connector (DLC).
2. Turn the ignition switch to RUN.
3. Start the engine.
4. Using the scan tool, monitor system voltage.

Is the measured voltage in the specified range?

Greater than 10.6V

Go to Step 3

Go to Battery Is Undercharged or Overcharged

3 |

1. Turn the ignition switch to OFF.
2. Turn the ignition switch to RUN.

Did the charge indicator turn on, then turn off after the normal bulb check?

--

Go to Step 4

Go to Step 11

4 | Is the vehicle a Buick? | -- | Go to Step 13 | Go to Step 5
5 |

1. Turn the ignition switch to RUN.
2. Start the engine and keep the engine running at fast idle.
3. Disconnect the battery thermistor connector, located near the battery.
4. Using a J 39200 digital multimeter (DMM) set to DC volts scale, measure the voltage across the battery terminals.

Is the measured voltage in the specified range?

13-16V

Go to Step 10

Go to Step 11

6 |

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 8

Go to Step 7

7 |

1. Check the BATT THER fuse for an open.
2. If the fuse is open, repair CKT 540 (ORN) short to ground.
3. If the fuse is OK, repair open or high resistance in CKT 540 (ORN).

Is the repair complete?

--

Go to Step 18

--

8 |

1. Disconnect the generator connector.
2. Connect a fused jumper from generator harness connector terminal S 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 10

Go to Step 9

9 | Repair high resistance or open in CKT 725 (LT BLU). Is the repair complete? | -- | Go to Step 18 | --
10 |

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

Is the repair complete?

--

Go to Step 18

--

11 |

1. Turn the ignition switch to LOCK.
2. Disconnect the powertrain control module (PCM) connector C2.
3. Turn the ignition switch to RUN.

Did the charge indicator remain on after the normal bulb check?

--

Go to Step 12

Go to Step 13

12 | Replace the instrument cluster. Refer to Instrument Cluster Replacement in Instrument Panel, Gauges and Console. Is the repair complete? | -- | Go to Step 18 | --
13 | Check CKT 225 (RED) for an open or short to ground. Is the circuit OK? | -- | Go to Step 15 | Go to Step 14
14 | Repair the open or short to ground on CKT 225 (RED). Is the repair complete? | -- | Go to Step 18 | --
15 | Check CKT 23 (GRY) for an open or short to ground. Is the circuit OK? | -- | Go to Step 17 | Go to Step 16
16 | Repair the open or short to ground on CKT 23 (GRY). Is the repair complete? | -- | Go to Step 18 | --
17 |

1. Check the powertrain control module (PCM) connectors for poor terminal contact.
2. If OK, replace the PCM. Refer to Powertrain Control Module Replacement/Programming in Engine Controls.

Is the repair complete?

--

Go to Step 18

--

18 |

1. Make sure any components removed during diagnosis are installed in place and that all connectors are connected.
2. Repeat the system check. Refer to Charging System Check .

Is the system check complete?

--

System OK

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