Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
|
Important: A short to ground will cause an open fuse(s). Before performing this diagnostic procedure, inspect the fuse(s) for an open. | ||||
1 |
Does the rear defogger grid warm? | -- | Go to Step 2 | Go to Step 3 |
2 | Replace the faulty relay. Is the repair complete? | -- | Go to Defogger System Check | -- |
3 |
Does the test lamp light? | -- | Go to Step 4 | Go to Step 23 |
4 |
Does the test lamp light? | -- | Go to Step 5 | Go to Step 14 |
5 |
Does the test lamp light? | -- | Go to Step 6 | Go to Step 7 |
6 |
Does the test lamp light? | -- | Go to Step 8 | Go to Step 9 |
7 | Repair the open in CKT 293 between the underhood wiring junction block and the left IP junction block. Refer to Wiring Repairs in Wiring Systems. Is the repair complete? | -- | Go to Defogger System Check | -- |
8 |
Does the test lamp light? | -- | Go to Step 10 | Go to Step 11 |
9 | Replace the left IP junction block. Is the repair complete? | -- | Go to Defogger System Check | -- |
10 |
Does the test lamp light? | -- | Go to Step 12 | Go to Step 13 |
11 | Repair the open in CKT 293 between the rear defogger grid and the left IP junction block. Refer to Wiring Repairs in Wiring Systems. Is the repair complete? | -- | Go to Defogger System Check | -- |
12 | Repair the open in the rear defogger grid or in CKT 900 (Olds) or in CKT 850 (Pontiac) between the rear antenna/defogger grid connector and ground. Refer to Grid Line Repair in Stationary Windows and Wiring Repairs in Wiring Systems. Is the repair complete? | -- | Go to Defogger System Check | -- |
13 | Repair the open in CKT 850 between the rear defogger grid and ground splice pack G402. Refer to Wiring Repairs in Wiring Systems. Is the repair complete? | -- | Go to Defogger System Check | -- |
14 |
Does the test lamp light? | -- | Go to Step 15 | Go to Step 23 |
15 | Use the J 39200 in order to backprobe underhood junction block connector C3 and measure the voltage between terminal A4 and ground. Does the voltage measure within the specified range? | B+ | Go to Step 16 | Go to Step 23 |
16 |
Does the voltage measure within the specified range? | B+ | Go to Step 17 | Go to Step 18 |
17 | Use the J 39200 in order to measure the voltage between terminal C and terminal K of heater and A/C control assembly connector C2. Does the voltage measure within the specified range? | B+ | Go to Step 19 | Go to Step 20 |
18 | Repair the open in CKT 41 between the heater and A/C control assembly and the underhood junction block. Refer to Wiring Repairs in Wiring Systems. Is the repair complete? | -- | Go to Defogger System Check | -- |
19 | Use the J 39200 in order to measure the voltage between terminal D and terminal K of heater and A/C control assembly connector C2. Does the voltage measure within the specified range? | B+ | Go to Step 21 | Go to Step 22 |
20 | Repair the open in CKT 251 between the heater and A/C control assembly and ground splice pack G204. Refer to Wiring Repairs in Wiring Systems. Is the repair complete? | -- | Go to Defogger System Check | -- |
21 | Replace the heater and A/C control assembly. Refer to LINK Control Assembly Replacement in HVAC Systems with A/C. Is the repair complete? | -- | Go to Defogger System Check | -- |
22 | Repair the open in CKT 193 between the heater and A/C control assembly and the underhood junction block. Refer to Wiring Repairs in Wiring Systems. Is the repair complete? | -- | Go to Defogger System Check | -- |
23 | Replace the underhood junction block. Refer to Underhood Fuse Block Replacement in Engine Electrical. Is the repair complete? | -- | Go to Defogger System Check | -- |
