Bus +/- Signals 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 to 12-volts, probe the ground circuit. If the test light illuminated, go to the next step. If the test light did 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 illuminated, go to the next step. If the test light did not illuminate, 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 test light illuminated, go to the next step. If the test light did not illuminate, repair the fused ignition switch output circuit for an open.
- Disconnect the instrument cluster harness connector. Use Scope Input Cable (CH7058), Cable-To-Probe adapter (CH7062), and the Red and test probes. Connect the Scope Input Cable to the channel one connector on the DRBIII. 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 DRBIII lab scope. If the voltage pulses from 0 to approximately 7.5 volts, replace the instrument cluster. See INSTRUMENT CLUSTER under REMOVAL & INSTALLATION in appropriate ANALOG INSTRUMENT PANELS article. If the voltage does not pulse from 0 to approximately 7.5 volts, repair the PCI bus circuit for an open.
NOTE:
If the vehicle is equipped with the AutoStick feature, it may be necessary to probe both Fused Ignition Switch Output circuits.
NOTE:
Ensure there is PCI Bus communication with other modules on the vehicle before proceeding. If not, refer to the symptom list from the menu and repair as necessary. See SYMPTOM INDEX table under SELF-DIAGNOSTIC SYSTEM.