Rear Window Defogger Inoperative W/ATC

Turn ignition on. Using scan tool, check EBL SW status. Press defogger switch on and off. If scan tool displays OPEN and CLOSED, go to next step. If scan tool does not display OPEN and CLOSED, replace Automatic Temperature Control (ATC) head.
Turn ignition off. Measure resistance between ground and left side bus bar on rear window. If resistance is 5 ohms or less, go to next step. If resistance is greater than 5 ohms, repair rear window defogger grid ground wire.
Turn ignition on. Turn defogger on. Connect a test light between ground and right side bus bar on rear window. If test light does not illuminate, go to next step. If test light illuminates, repair open in rear window defogger grid. See appropriate REAR WINDOW DEFOGGERS article.
Turn ignition off. Remove rear window defogger relay. Rear window defogger relay is located on right side of trunk. Measure voltage at terminals No. 2 and 5 (Black/Pink wires) at rear window defogger relay socket. If battery voltage exists at both terminals, go to next step. If battery voltage does not exist at both terminals, go to step 8 .

CAUTION: DO NOT leave jumper wire connected for a long period of time.

Using a fused jumper wire, connect terminals No. 1 (Black/White wire) and No. 2 (Black/Pink wire) at rear window defogger relay socket. Measure voltage at right side bus bar on rear window. If battery voltage exists, go to next step. If battery voltage does not exist, repair open in Black/White wire between rear window defogger relay and rear window defogger grid. On vehicles equipped with radio antenna in rear window, check for open circuit in rear window defogger/antenna module. Rear window defogger/antenna module is located behind right rear quarter trim panel.
Turn ignition off. Connect a test light between terminals No. 5 (Black/Pink wire) and No. 4 (Dark Blue/White wire) at rear window defogger relay socket. Turn ignition on. Turn rear window defogger on. If test light does not illuminate, go to next step. If test light illuminates, replace rear window defogger relay.
Turn ignition off. Disconnect Body Control Module (BCM) harness connector C4. Connect jumper wire between ground and terminal No. 14 (Dark Blue/White wire) at BCM harness connector C4. See Figure . Measure resistance between ground and terminal No. 4 (Dark Blue/White wire) at rear window defogger relay socket. If resistance is 5 ohms or less, replace BCM. If resistance is greater than 5 ohms, repair open in Dark Blue/White wire between BCM and rear window defogger relay.
Turn ignition off. Remove and inspect fuse "A" in Power Distribution Center (PDC). If fuse is blown, go to next step. If fuse is okay, repair open in Black/Pink wire between PDC and rear window defogger relay.
Ensure fuse "A" is still removed. Measure resistance between ground and terminals No. 2 and 5 (Black/Pink wires) at rear window defogger relay socket. If resistance is greater than 5 ohms at both terminals, go to next step. If resistance is 5 ohms or less at either terminal, repair short to ground in Black/Pink wire between rear window defogger relay and PDC.
Replace fuse "A". Install rear window defogger relay. Turn ignition on. Turn rear window defogger on. If rear window defogger operates without blowing fuse, system is currently operating properly. If rear window defogger operates and blows fuse, repair short to ground in Black/White wire between rear window defogger relay and rear window defogger grid. On vehicles equipped with radio antenna in rear window, check for short to ground in rear window defogger/antenna module. Rear window defogger/antenna module is located behind right rear quarter trim panel.