Bus +/- Signal Open Or No Response From Instrument Cluster
NOTE:
After making any repairs, perform BODY VERIFICATION TEST
under VERIFICATION TESTS.
- Turn ignition off. Turn off all lights. Disconnect Black 26-pin instrument cluster connector, located behind left upper instrument panel. Using ohmmeter, check resistance between instrument cluster connector terminal No. 10, ground circuit (Black/Orange wire) and ground. See Fig 1 . If resistance is less than 5 ohms, leave instrument cluster connector disconnected and go to next step. If resistance is 10 ohms or more, repair open Black/Orange wire.
- Using a voltmeter, check voltage on instrument cluster connector terminal No. 21, fused B+ circuit (Pink wire). If voltage is 10 volts or more, go to next step. If voltage is less than 10 volts, replace open fuse No. 13 (15-amp) in PDC or repair open Pink wire.
- Turn ignition on. Using a voltmeter, check voltage on instrument cluster connector terminal No. 15, fused ignition switch output start/run circuit (Dark/Blue White wire). If voltage is 10 volts or more, go to next step. If voltage is less than 10 volts, replace open fuse No. 11 (10-amp) in fuse block or repair open Dark Blue/White wire.
- Ensure ignition is off. Connect scan tool to Data Link Connector (DLC). DLC is located on bottom of instrument panel, to left of brake pedal. See Figure . Turn ignition on. Using scan tool, attempt to communicate with other modules. If scan tool does not communicate with other modules, proceed to COMPLETE PCI BUS FAILURE test. If scan tool communicates with other modules, go to next step.
- Connect Scope Input Cable (CH7058) to channel one connector on scan tool. Connect Red and Black leads, and Cable-to-Probe Adapter (CH7062) to scope input cable. Go to next step.
- Using scan tool, select DRB STANDALONE, LAB SCOPE, LIVE, then 12-VOLT SQUARE WAVE. Press F2 for scope. Press F2 again and use down arrow to set voltage range to 20 volts. Press F2 again. Go to next step.
- Connect Black lead to ground. Connect Red lead to instrument cluster connector terminal No. 2, PCI bus circuit (Violet/Yellow wire). Turn ignition on. Observe voltage display on scan tool lab scope. If voltage pulses from zero to about 7.5 volts, replace instrument cluster. See ANALOG INSTRUMENT PANELS - NEON article. If voltage remains at zero volts, repair open Violet/Yellow wire.
NOTE:
If fused B+ circuit is open, Vacuum Fluorescent (VF) display will flash FUSE.