Bus +/- Signals Open From Automatic Temperature Control Module
NOTE:
This procedure applies to vehicles equipped with automatic A/C.
NOTE:
After making any repairs, perform BODY VERIFICATION TEST
under VERIFICATION TESTS.
- Turn ignition on. Using DVOM, select BODY then BODY COMPUTER. If scan tool identifies and/or communicates with Body Control Module (BCM), go to next step. If scan tool does not identify and/or communicate with BCM, go to BUS +/- SIGNALS OPEN OR NO RESPONSE FROM BCM .
- Turn ignition off. Disconnect A/C-heater control panel connectors. Measure resistance between ground and A/C-heater control panel connector C2 terminal No. 11 (Black/Orange wire). See Figure . If resistance is 5 ohms or more, repair open in Black/Orange wire. If resistance is less than 5 ohms, go to next step.
- Using a test light connected to ground, probe A/C-heater control panel connector C2 terminal No. 4 (Gray/Red wire). If test light illuminates, go to next step. If test light does not illuminate, repair open in Gray/Red wire between A/C-heater control panel and fuse No. 14 located in Intelligent Power Module (IPM). See Fig 1 .
- Turn ignition on. Using a test light connected to ground, probe A/C-heater control panel connector C2 terminal No. 5 (Gray/Pink wire). If test light illuminates, go to next step. If test light does not illuminate, repair open in Gray/Pink wire between A/C-heater control panel and BCM connector C4 terminal No. 10. See Figure .
- Obtain Scope Input Cable (CH7058), Cable To Probe Adapter (CH7062) and Red and Black test probes. Connect scope input cable to channel 1 connector on scan tool. Connect Red and Black test probes and probe adapter to scope input cable. Select STANDALONE on scan tool. Select LAB SCOPE then LIVE DATA. Select 12V SQUARE WAVE. Press F2 for scope then enter to select channel. Press F2 again and use down arrow to set voltage range to 20 volts. Press F2 again to complete. Connect Black probe to ground and Red probe A/C-heater control panel connector C2 terminal No. 6 (White/Violet wire). Turn ignition on. Monitor scope on scan tool. If voltage pulses between zero and 7.5 volts, go to next step. If voltage does not pulse between zero and 7.5 volts, repair open in White/Violet wire (PCI bus circuit) between A/C-heater control panel and diagnostic junction port terminal No. 2. See Figure .
- Replace A/C-heater control panel. See A/C-HEATER CONTROL PANEL under REMOVAL & INSTALLATION.