BUS +/- Signals Open Or No Response From Sentry Key Immobilizer Module

Possible Causes are:

• ATTEMPT TO COMMUNICATE WITH THE BCM
• GROUND CIRCUIT OPEN
• FUSED IGNITION SWITCH OUTPUT CIRCUIT OPEN
• FUSED B (+) CIRCUIT OPEN
• OPEN PCI BUS CIRCUIT
• SENTRY KEY IMMOBILIZER MODULE

1. Turn ignition on. Using the DRBIII(R), enter Body then Body Computer. Was the DRBIII(R) able to I/D or communicate with the BCM? If yes, go to next step. If no, diagnose using appropriate procedure. See COMMUNICATION  under DIAGNOSTIC TESTS. Perform SKIS VERIFICATION  under VERIFICATION TESTS.
2. Turn ignition off. Disconnect the SKIM harness connector. Using a 12-volt test light connected to 12 volts, probe the ground circuit. Is the test light illuminated? If yes, go to next step. If no, repair the ground circuit for an open. Perform SKIS VERIFICATION  under VERIFICATION TESTS.
3. Turn ignition off. Disconnect the SKIM harness connector. Turn ignition on. Using a 12-volt test light connected to ground, probe the Fused Ignition Switch Output circuit. Is the test light illuminated? If yes, go to next step. If no, repair the Fused Ignition Switch Output circuit for an open. Perform SKIS VERIFICATION  under VERIFICATION TESTS.
4. Turn ignition off. Disconnect the SKIM harness connector. Using a 12-volt test light connected to ground, probe the Fused B (+) circuit. Is the test light illuminated? If yes, go to next step. If no, repair the Fused B+ circuit for an open. Perform SKIS VERIFICATION  under VERIFICATION TESTS.
5. Disconnect the SKIM 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 DRBIII(R). Attach the Red and Black leads and the cable to probe adapter to the scope input cable. Using the DRBIII(R), 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 SKIM connector. Turn ignition on. Observe the voltage display on the DRBIII(R) Lab Scope. Does the voltage pulse from 0 to approximately 7.5 volts? If yes, go to next step. If no, repair the PCI Bus circuit for an open. Perform SKIS VERIFICATION  under VERIFICATION TESTS.
6. Step 6 If there are no possible causes remaining, replace and program the Sentry Key Immobilizer Module. Perform SKIS VERIFICATION  under VERIFICATION TESTS.