For 1990-2009 cars

Step | Action | Yes | No
--- | --- | --- | ---
1 | Did you review the Rear Window Defogger Description and the Rear Window Defogger Circuit Description operation and perform the necessary inspections? | Go to Step 2 | Go to Symptoms - Stationary Windows
2 | Verify that the defogger is inoperative. Is the defogger inoperative? | Go to Step 3 | Go to Testing for Intermittent Conditions and Poor Connections
3 | Connect a test lamp between the defogger connector 1 and ground. Does the test lamp illuminate with the ignition switch ON and the defogger switch depressed? | Go to Step 4 | Go to Step 7
4 | Connect a test lamp between the defogger connector 2 and B+. Does the test lamp illuminate? | Go to Step 5 | Go to Step 6
5 | Repair the defogger grid. Refer to Grid Line Repair and/or Bus Bar Lead Terminal Repair . Is the repair complete? | Go to Step 22 | --
6 | Repair the open in the BLK wire between the defogger connector 2 and G401. Refer to Wiring Repairs in Wiring Systems. Is the repair complete? | Go to Step 22 | --
7 | Test for battery voltage at terminal 2 of the defogger relay with the ignition switch ON and the defogger switch depressed. Is battery voltage present? | Go to Step 8 | Go to Step 9
8 | Repair the open in the BLK /RED wire between the defogger relay and the defogger grid. Refer to Wiring Repairs in Wiring Systems. Is the repair complete? | Go to Step 22 | --
9 |

1. Test for battery voltage at terminal 1 of the defogger relay with the ignition switch in the ON position.
2. Test for battery voltage at terminal 6 of the defogger relay with the ignition switch in the ON position.

Is battery voltage present?

Go to Step 11

Go to Step 10

10 | Repair the open in the YEL/GRN wire between the defogger relay and S259. Refer to Wiring Repairs in Wiring Systems. Is the repair complete? | Go to Step 22 | --
11 |

1. Disconnect the defogger relay connector.
2. Connect a test lamp between the defogger relay connector 3 and B+.

Does the test lamp illuminate?

Go to Step 13

Go to Step 12

12 | Repair the open in the BLK wire between the defogger relay and S248. Refer to Wiring Repairs in Wiring Systems. Is the repair complete? | Go to Step 22 | --
13 |

1. Connect the defogger relay connector.
2. Test for voltage at terminal 5 of the defogger relay with the ignition switch ON and the defogger switch depressed.

Is the voltage 6-8 volts?

Go to Step 14

Go to Step 21

14 | Test for voltage at terminal 1 of the defogger switch with the ignition switch ON and the defogger switch depressed. Is the voltage 6-8 volts? | Go to Step 16 | Go to Step 15
15 | Repair the open in the RED/BLU wire between the defogger relay and the defogger switch. Refer to Wiring Repairs in Wiring Systems. Is the repair complete? | Go to Step 22 | --
16 |

1. Disconnect the defogger switch connector.
2. Connect a test lamp between the defogger switch connector 4 and B+.

Does the test lamp illuminate?

Go to Step 18

Go to Step 17

17 | Repair the open in the BLK wire between the defogger switch and S248. Refer to Wiring Repairs in Wiring Systems. Is the repair complete? | Go to Step 22 | --
18 | Connect a test lamp between the defogger switch connector 3 and B+. Does the test lamp illuminate? | Go to Step 20 | Go to Step 19
19 | Repair the open in the BLK /RED wire between the defogger switch and S257. Refer to Wiring Repairs in Wiring Systems. Is the repair complete? | Go to Step 22 | --
20 | Replace the defogger switch. Refer to Rear Window Defogger Switch Replacement . Is the repair complete? | Go to Step 22 | --
21 | Replace the defogger relay. Refer to Rear Window Defogger Relay Replacement . Is the repair complete? | Go to Step 22 | --
22 | Operate the system in order to verify the repair. Did you correct the condition? | System OK | Go to Step 3