Diagnostic Aids
The body control module (BCM) imposes a time limit on the heating of the rear window. Power is toggled ON or OFF as the heated-rear-window momentary-contact switch is pressed. The BCM enables heating of the rear window for a period of 15 minutes with subsequent activation of the switch resetting the time to 15 minutes. Rear window heating is available only when the ignition is ON. This system defaults to OFF when the ignition is turned OFF. The BCM controls the heated-rear-window operation after the system is switched on.
Step | Action | Values | Yes | No |
|---|---|---|---|---|
Schematic Reference: Defogger Schematics | ||||
1 | Did you perform the Diagnostic System Check - Vehicle? | -- | Go to Step 2 | Go to Diagnostic System Check - Vehicle in Vehicle DTC Information |
2 | Are the ignition switch and control circuits functioning properly? | -- | Go to Step 3 | Go to Step 20 |
3 |
Does the rear window defogger switch LED illuminate? | Go to Step 4 | Go to Step 5 | |
4 | With the ignition ON and the rear window defogger switch LED illuminated, does the rear window defog? | System OK | Go to Step 13 | |
5 |
Does the scan tool display the defogger switch is ON? | Go to Step 6 | Go to Step 11 | |
6 |
Does the rear window defogger switch LED illuminate? | Go to Step 21 | Go to Step 7 | |
7 | With the ignition ON, back-probe the ground circuit of the rear window defogger switch LED at the switch connector with a fused jumper wire to ground. Refer to Using Fused Jumper Wires in Wiring Systems. Does the rear window defogger switch LED illuminate? | Go to Step 22 | Go to Step 8 | |
8 | With the ignition ON, back-probe the rear window defogger switch battery positive feed with a voltmeter to ground. Refer to Measuring Voltage in Wiring Systems. Is the value as specified? |
Battery Voltage | Go to Step 23 | Go to Step 9 |
9 | With the ignition ON, back-probe the output side of fuse F13 with a voltmeter to ground. Refer to Measuring Voltage in Wiring Systems. Is the value as specified? | Battery Voltage | Go to Step 24 | Go to Step 10 |
10 | Check fuse F13. Is the fuse OK? | Go to Step 25 | Go to Step 26 | |
11 |
Is the value as specified? | Battery Voltage | Go to Step 21 | Go to Step 12 |
12 |
Is the value as specified? | Battery Voltage | Go to Step 27 | Go to Step 23 |
13 |
Is the value as specified? | Battery Voltage | Go to Step 14 | Go to Step 15 |
14 |
Is the reading as specified? | Less than 1 ohms | Go to Step 28 | Go to Step 29 |
15 |
Is the value as specified? | Battery Voltage | Go to Step 30 | Go to Step 16 |
16 | Back-probe the defog relay switch side battery feed circuit with a voltmeter to ground. Refer to Measuring Voltage in Wiring Systems. Is the value as specified? | Battery Voltage | Go to Step 17 | Go to Step 31 |
17 |
Is the value as specified? | Battery Voltage | Go to Step 18 | Go to Step 24 |
18 |
Is the value as specified? | Less than 1 V | Go to Step 19 | Go to Step 32 |
19 | With the ignition ON, back-probe defog relay coil ground circuit with an ohmmeter to ground. Refer to Testing for Continuity in Wiring Systems. Is the value as specified? | Less than 1 ohms | Go to Step 33 | Go to Step 32 |
20 | Replace the ignition switch or repair ignition control circuit faults as necessary. Did you complete the repair? | Go to Step 34 | -- | |
21 | Replace the BCM. Refer to Body Control Module Replacement . Did you complete the repair? | Go to Step 34 | -- | |
22 | Repair the ground circuit of the rear window defogger switch LED. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | Go to Step 34 | -- | |
23 | Replace the rear window defogger switch. Did you complete the repair? | Go to Step 34 | -- | |
24 | Repair the load side circuit of fuse F13. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | Go to Step 34 | -- | |
25 | Repair the battery positive feed circuit between F13 and the battery. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | Go to Step 34 | -- | |
26 | Replace fuse F13. Did you complete the repair? | Go to Step 34 | -- | |
27 | Repair the rear window defogger switch output circuit between the switch and the BCM. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | Go to Step 34 | -- | |
28 | Replace or repair the rear window defogger element. Refer to Rear Window Replacement . Did you complete the repair? | Go to Step 34 | -- | |
29 | Repair the circuit between the ANT/DEFOG coil output of the radio antenna rear window defog module and ground. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | Go to Step 34 | -- | |
30 | Repair the circuit between the defog relay switch side and the radio antenna rear window defog module. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | Go to Step 34 | -- | |
31 | Repair the power supply circuit, including fuse F22. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | Go to Step 34 | -- | |
32 | Repair the circuit between the defog relay coil ground circuit and the BCM. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | Go to Step 34 | -- | |
33 | Replace the defog relay. Did you complete the repair? | Go to Step 34 | -- | |
34 | Operate the system in order to verify the repair. Did you correct the condition? | -- | System OK | Go to Step 3 |
