Bus +/- Signal Open Or No Response From Sentry Key Immobilizer Module

Possible Causes:

• Attempt To Communicate With The BCM
• Ground Circuit Open
• Fused Ignition Switch Output Circuit Open
• Fused B+ Circuit Open
• Sentry Key Immobilizer Module (SKIM)
• PCI Bus Circuit Open
• Body Control Module

Testing

1. Turn ignition off. Connect scan tool to Data Link Connector (DLC). Turn ignition on. Using scan tool, select BODY, then BODY COMPUTER. If scan tool communicates with Body Control Module (BCM), go to next step. If scan tool does not communicate with BCM, perform BUS +/- SIGNALS OPEN OR NO RESPONSE FROM BODY CONTROL MODULE  test.
2. Turn ignition off. Disconnect Sentry Key Immobilizer Module (SKIM) connector. Measure resistance between ground and SKIM connector terminal No. 5, ground circuit (Black/Light Green wire). See Figure . If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open in Black/Light Green wire.
3. Turn ignition on. Using a 12-volt test light connected to ground, probe SKIM connector terminal No. 4, fused ignition switch output circuit (Dark Blue/White wire). If test light illuminates, leave SKIM connector disconnected and go to next step. If test light does not illuminate, repair open in Dark Blue/White wire.
4. Using 12-volt test light connected to ground, probe SKIM connector terminal No. 6, fused B+ circuit (Pink wire). If test light illuminates, go to next step. If test light does not illuminate, repair open in Pink wire.
NOTE: Steps  5 - 7 are written specifically for use with Chrysler's Diagnostic Readout Box (DRBIII(R)) scan tool.
5. Turn ignition off. 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.
6. Using scan tool, select DRB STANDALONE, LAB SCOPE, LIVE DATA, 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.
7. Connect Black lead to chassis ground. Connect Red lead to SKIM 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 SKIM. See Figure -Figure . See SENTRY KEY IMMOBILIZER MODULE  under REMOVAL & INSTALLATION. If voltage does not pulse from zero to about 7.5 volts, go to next step.
8. Turn ignition off. Disconnect SKIM connector. Disconnect BCM connector C1. Measure resistance of PCI bus circuit (Violet/Yellow wire) between SKIM connector terminal No. 2 and BCM connector C1 terminal No. 12. See Figure and Figure . If resistance is less than 5 ohms, replace BCM. See BODY CONTROL MODULE  under REMOVAL & INSTALLATION. If resistance is 5 ohms or more, repair open in Violet/Yellow wire.