For 1990-2009 cars

Step | Action | Value(s) | Yes | No
--- | --- | --- | --- | ---
1 |

1. Place the ignition switch in the run position.
2. Disconnect the rear defogger relay.
3. Connect a test lamp between the following terminals and ground:

• | Terminal 86

• | Terminal 87

Does the test lamp illuminate at both terminals?

--

Go to Step 2

Go to Step 3

2 | Connect a test lamp between terminal 30 and terminal 87 of the rear defogger relay connector. Does the test lamp illuminate? | -- | Go to Step 4 | Go to Step 7
3 | Repair an open in CKT 41 or in CKT 1340. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | -- | System OK | --
4 | Connect a test lamp between terminal 30 and terminal 85 of the rear defogger relay connector. Does the test lamp illuminate? | -- | Go to Step 5 | Go to Step 9
5 |

1. Backprobe the rear defogger switch connector terminal A (Buick/Oldsmobile) or terminal 2 (Pontiac) and ground.
2. Press the rear defogger switch.

Does the test lamp illuminate?

--

Go to Step 6

Go to Step 10

6 | Test CKT 292 and CKT 681 for an open. Is an open in CKT 292 or in CKT 681? | -- | Go to Step 12 | Go to Step 11
7 | Test for an open in CKT 293 and in CKT 150. Is an open in CKT 293 or in CKT 150? | -- | Go to Step 12 | Go to Step 13
8 | Test for an open in CKT 293 or in the rear defogger grid. Is an open in CKT 293 or in the rear defogger grid? | -- | Go to Step 12 | Go to Step 14
9 | Test for an open in CKT 681. Is an open in CKT 681? | -- | Go to Step 12 | Go to Step 11
10 | Test for an open in CKT 39. Is an open in CKT 39? | -- | Go to Step 12 | Go to Step 14
11 | Replace the multi-function alarm module. Refer to Multifunction Alarm Module Replacement in Keyless Entry. Did you complete the repair? | -- | System OK | --
12 | Repair the open in the faulty CKT. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | -- | System OK | --
13 |

• | Replace or repair the rear defogger grid (w/o rear grid antenna). Refer to Grid Line Repair .

• | Replace the antenna/rear defogger module (w/ rear grid antenna). Refer to Antenna/Rear Defogger Module Replacement.

Did you complete the repair?

--

System OK

--

14 | Replace the rear defogger switch. Refer to Rear Window Defogger Switch Replacement . Did you complete the repair? | -- | System OK | --