Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
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HOMESERVICE MANUALSCHEVROLET2002CHEVY EXPRESS G3500, VAN PASSENGER EXTENDED, 8.1 GREPAIR AND DIAGNOSIS (SINGLE PAGE)ACCESSORIES & EQUIPMENTANTI-THEFT SYSTEMSTHEFT DETERRENT SYSTEMDIAGNOSTIC TESTSDTC B0688: SECURITY INDICATOR CIRCUIT FAULTTESTING
2002 Chevrolet Chevy Express G3500, Van Passenger Extended, 8.1 G
DTC B0688: Security Indicator Circuit Fault: Testing
2002 Chevrolet Chevy Express G3500, Van Passenger Extended, 8.1 GSECTION Testing
- If theft deterrent diagnostic system check has been performed, go to next step. If theft deterrent diagnostic system check has not been performed, go to THEFT DETERRENT DIAGNOSTIC SYSTEM CHECK under SELF DIAGNOSTIC SYSTEM.
- Turn ignition switch to OFF position. Connect scan tool to Data Link Connector (DLC), located below steering column. See Figure . Turn ignition switch to RUN position. Using scan tool, command security indicator on and off. If security indicator does not change state, go to next step. If security indicator changes states with each command, go to DIAGNOSTIC AIDS .
- Turn ignition switch to OFF position. Disconnect Passlock(tm) Module 16-pin harness connector. Turn ignition switch to RUN position. If security indicator is illuminated, go to next step. If security indicator is not illuminated go to step 5 .
- Check for short to ground in Yellow wire (security indicator control circuit) between Passlock(tm) module harness connector terminal B2 and Instrument Panel Cluster (IPC) harness connector terminal A4. See Fig 1 and Fig 2 . If Yellow wire is okay, go to step 6 . If Yellow wire is not okay, repair as necessary. After repair, go to step 9 .
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.