Bus +/- Signal Open Or No Response From Instrument Cluster
NOTE:
After making any repairs, perform BODY VERIFICATION TEST
under VERIFICATION TESTS.
- Turn the ignition off. Turn all lights off. Disconnect the instrument cluster harness connector. Using a 12-volt test light connected to12-volts, probe the ground circuit. If the test light is illuminated, go to the next step. If the test light does not illuminate, repair the ground circuit for an open.
- Turn the ignition off. Disconnect the instrument cluster harness connector. See Fig 1 . Using a 12-volt test light connected to ground, probe the fused B+ circuit. If the test light is illuminated, go to the next step. If the test light is not illuminated, repair the fused B+ circuit for an open.
- Turn the ignition off. Disconnect the instrument cluster harness connector. Turn the ignition on. Using a 12-volt test light connected to ground, probe the fused ignition switch output circuit. If the vehicle is equipped with the Autostick feature, it may be necessary to probe both fused ignition switch output circuits. If the test light is illuminated, go to the next step. If the test light is not illuminated, repair the fused ignition switch output circuit for an open.
- Ensure there is PCI Bus communication with other modules on the vehicle before proceeding. If not, refer to the symptom identification table and repair as necessary. See SYMPTOM INDEX table. Disconnect the instrument cluster harness connector. Use Scope Input Cable (CH7058), Cable-To-Probe Adapter (CH7062), and the Red and Black test probes. Connect the scope input cable to the channel one connector on the DRB. Attach the Red and Black leads and the cable to probe adapter to the scope input cable. With the DRBIII select PEP MODULE TOOLS. Select LAB SCOPE. Select LIVE DATA. Select 12-volt square wave. Press F2 for scope. Press F2 and use the down arrow to set voltage range to 20 volts. Set probe to x10. Press F2 again when complete. Connect the Black lead to the chassis ground. Connect the Red lead to the PCI Bus circuit in the instrument cluster connector. Turn the ignition on. Observe the voltage display on the DRB lab scope. If the voltage pulses from 0 to approximately 7.5 volts, replace the instrument cluster. See INSTRUMENT CLUSTER under REMOVAL & INSTALLATION in ANALOG INSTRUMENT PANELS article. If the voltage does not pulse, repair the PCI Bus circuit for an open.