For 1990-2009 cars

## Rear Window Defogger Inoperative Oldsmobile

### Test Description

The number below refers to the step number on the diagnostic table.

1. Listen for an audible click when the RR DEFOG relay operates. Command both the ON and OFF states of the RR DEFOG relay. Repeat the commands as necessary.

Step | Action | Yes | No
--- | --- | --- | ---
Schematic Reference: Defogger Schematics Connector End View Reference: Stationary Windows Connector End Views
1 | Did you review the operation of the rear window defogger system and perform the necessary inspections? | Go to Step 2 | Go to Symptoms - Stationary Windows
2 |

1. Turn ON the ignition, with the engine OFF.
2. Depress the rear window defogger switch.
3. Observe the rear window defogger indicator on the HVAC control assembly.

Does the rear window defogger indicator illuminate?

Go to Step 3

Go to Step 5

3 | Connect a test lamp between the rear window defogger grid and ground. Does the test lamp illuminate? | Go to Step 4 | Go to Step 7
4 | Connect a test lamp between the left side of the rear window defogger grid and the right side of the rear window defogger grid. Does the test lamp illuminate? | Go to Testing for Intermittent Conditions and Poor Connections in Wiring Systems | Go to Step 13
5 |

1. Turn OFF the ignition.
2. Disconnect the harness connector C2 of the HVAC control assembly.
3. Turn ON the ignition, with the engine OFF.
4. Connect a test lamp between the ignition voltage circuit of the HVAC control assembly and ground.

Does the test lamp illuminate?

Go to Step 6

Go to Step 21

6 | Connect a test lamp between the ignition voltage circuit and the ground circuit of the HVAC control assembly. Does the test lamp illuminate? | Go to Step 14 | Go to Step 22
7 | Command the RR DEFOG relay ON and OFF, by depressing the rear window defogger switch on the HVAC control assembly. Do you hear a click when you command the RR DEFOG relay ON and OFF? | Go to Step 10 | Go to Step 8
8 |

1. Turn OFF the ignition.
2. Disconnect the RR DEFOG relay.
3. Turn ON the ignition, with the engine OFF.
4. Connect a test lamp between the ignition voltage circuit of the RR DEFOG relay coil and ground.

Does the test lamp illuminate?

Go to Step 9

Go to Step 23

9 |

1. Connect a test lamp between the ignition voltage circuit of the RR DEFOG relay coil and the control circuit of the RR DEFOG relay.
2. Depress the rear window defogger switch.

Does the test lamp illuminate?

Go to Step 19

Go to Step 14

10 |

1. Turn OFF the ignition.
2. Disconnect the RR DEFOG relay.
3. Connect a test lamp between the battery positive voltage circuit of the RR DEFOG relay switched input and ground.

Does the test lamp illuminate?

Go to Step 11

Go to Step 15

11 |

1. Connect a 30-ampere fused jumper between the battery positive voltage circuit of the RR DEFOG relay switched input and the relay switched output to the supply voltage circuit of the rear defogger grid.
2. Connect a test lamp between the rear window defogger grid and a good ground.

Does the test lamp illuminate?

Go to Step 19

Go to Step 12

12 |

1. Turn OFF the ignition.
2. Disconnect the harness connector of the antenna amplifier module.
3. Turn ON the ignition, with the engine OFF.
4. Connect a test lamp between the supply voltage circuit of the rear window defogger grid and ground.

Does the test lamp illuminate?

Go to Step 16

Go to Step 25

13 | Test the ground circuit of the rear window defogger grid for an open or for a high resistance. Refer to Circuit Testing and to Wiring Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 30 | Go to Step 17
14 | Test the control circuit of the RR DEFOG relay for an open or for a short to voltage. Refer to Circuit Testing and to Wiring Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 30 | Go to Step 18
15 | Test the battery positive voltage circuit of the RR DEFOG relay switched input for an open or for a high resistance. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 30 | Go to Step 24
16 | Test the supply voltage circuit of the rear window defogger grid between the antenna amplifier module and the rear window defogger grid for an open or for a high resistance. Refer to Circuit Testing and to Wiring Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 30 | Go to Step 20
17 | Inspect for a poor connection at the antenna choke. Refer to Testing for Intermittent Conditions and Poor Connections and to Connector Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 30 | Go to Step 26
18 | Inspect for a poor connection at the harness connector of the HVAC control assembly. Refer to Testing for Intermittent Conditions and Poor Connections and to Connector Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 30 | Go to Step 27
19 | Inspect for a poor connection at the RR DEFOG relay. Refer to Testing for Intermittent Conditions and Poor Connections and to Connector Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 30 | Go to Step 28
20 | Inspect for a poor connection at the harness connector of the antenna amplifier module. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 30 | Go to Step 29
21 | Repair an open or a short to ground in the ignition voltage circuit of the HVAC control assembly. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | Go to Step 30 | --
22 | Repair an open or for a high resistance in the ground circuit of the HVAC control assembly. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | Go to Step 30 | --
23 | Repair an open or a high resistance in the ignition voltage circuit of the RR DEFOG relay coil. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | Go to Step 30 | --
24 | Repair a short to ground in the supply voltage circuit of the rear window defogger grid. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | Go to Step 30 | --
25 | Repair an open or a high resistance in the supply voltage circuit of the rear window defogger grid. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | Go to Step 30 | --
26 | Replace the antenna choke. Refer to Antenna Module Coil Replacement in Entertainment. Did you complete the replacement? | Go to Step 30 | --
27 | Replace the HVAC control assembly. Refer to Heater and Air Conditioning Control Replacement in HVAC Systems -- Manual. Did you complete the replacement? | Go to Step 30 | --
28 | Replace the RR DEFOG relay. Did you complete the replacement? | Go to Step 30 | --
29 | Replace the antenna amplifier module. Refer to Radio Antenna Module Replacement in Entertainment. Did you complete the replacement? | Go to Step 30 | --
30 | Operate the system in order to verify the repair. Did you correct the condition? | System OK | Go to Step 2

## Rear Window Defogger Inoperative Pontiac

### Test Description

The number below refers to the step number on the diagnostic table.

1. Listen for an audible click when the RR DEFOG relay operates. Command both the ON and OFF states of the RR DEFOG relay. Repeat the commands as necessary.

Step | Action | Yes | No
--- | --- | --- | ---
Schematic Reference: Defogger Schematics Connector End View Reference: Stationary Windows Connector End Views
1 | Did you review the operation of the rear window defogger system and perform the necessary inspections? | Go to Step 2 | Go to Symptoms - Stationary Windows
2 |

1. Turn ON the ignition, with the engine OFF.
2. Depress the rear window defogger switch.
3. Observe the rear window defogger indicator on the HVAC control assembly.

Does the rear window defogger indicator illuminate?

Go to Step 3

Go to Step 5

3 | Connect a test lamp between the rear window defogger grid and a good ground. Does the test lamp illuminate? | Go to Step 4 | Go to Step 7
4 | Connect a test lamp between the left side of the rear window defogger grid and the right side of the rear window defogger grid. Does the test lamp illuminate? | Go to Testing for Intermittent Conditions and Poor Connections in Wiring Systems | Go to Step 16
5 |

1. Turn OFF the ignition.
2. Disconnect the harness connector C2 of the HVAC control assembly.
3. Turn ON the ignition, with the engine OFF.
4. Connect a test lamp between the ignition voltage circuit of the HVAC control assembly and a good ground.

Does the test lamp illuminate?

Go to Step 6

Go to Step 17

6 | Connect a test lamp between the ignition voltage circuit and the ground circuit of the HVAC control assembly. Does the test lamp illuminate? | Go to Step 12 | Go to Step 18
7 | Command the RR DEFOG relay ON and OFF, by depressing the rear window defogger switch on the HVAC control assembly. Do you hear a click when you command the RR DEFOG relay ON and OFF? | Go to Step 10 | Go to Step 8
8 |

1. Turn OFF the ignition.
2. Disconnect the RR DEFOG relay.
3. Turn ON the ignition, with the engine OFF.
4. Connect a test lamp between the ignition voltage circuit of the RR DEFOG relay coil and a good ground.

Does the test lamp illuminate?

Go to Step 9

Go to Step 19

9 |

1. Connect a test lamp between the ignition voltage circuit of the RR DEFOG relay coil and the control circuit of the RR DEFOG relay.
2. Depress the rear window defogger switch.

Does the test lamp illuminate?

Go to Step 15

Go to Step 12

10 |

1. Turn OFF the ignition.
2. Disconnect the RR DEFOG relay.
3. Connect a test lamp between the battery positive voltage circuit of the RR DEFOG relay switched input and a good ground.

Does the test lamp illuminate?

Go to Step 11

Go to Step 13

11 |

1. Connect a 30 amp fused jumper wire between the battery positive voltage circuit of the RR DEFOG relay switched input and the relay switched output to the supply voltage circuit of the rear window defogger grid.
2. Connect a test lamp between the rear window defogger grid and a good ground.

Does the test lamp illuminate?

Go to Step 15

Go to Step 21

12 | Test the control circuit of the RR DEFOG relay for an open or short to voltage. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 24 | Go to Step 14
13 | Test the battery positive voltage circuit of the RR DEFOG relay switched input for an open or high resistance. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 24 | Go to Step 20
14 | Inspect for a poor connection at the harness connector of the HVAC control assembly. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 24 | Go to Step 22
15 | Inspect for a poor connection at the RR DEFOG relay. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 24 | Go to Step 23
16 | Repair an open or high resistance in the ground circuit of the rear window defogger grid. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | Go to Step 24 | --
17 | Repair an open or short to ground in the ignition voltage circuit of the HVAC control assembly. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | Go to Step 24 | --
18 | Repair an open or high resistance in the ground circuit of the HVAC control assembly. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | Go to Step 24 | --
19 | Repair an open or high resistance in the ignition voltage circuit of the RR DEFOG relay coil. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | Go to Step 24 | --
20 | Repair a short to ground in the supply voltage circuit of the rear window defogger grid. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | Go to Step 24 | --
21 | Repair an open or high resistance in the supply voltage circuit of the rear window defogger grid. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | Go to Step 24 | --
22 | Replace the HVAC control assembly. Refer to Heater and Air Conditioning Control Replacement in HVAC Systems - Manual. Did you complete the replacement? | Go to Step 24 | --
23 | Replace the RR DEFOG relay. Did you complete the replacement? | Go to Step 24 | --
24 | Operate the system in order to verify the repair. Did you correct the condition? | System OK | Go to Step 2