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 MANUALSCHEVROLET1997CHEVY EXPRESS G3500, VAN CARGO, 6.5 FREPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT CARSECTION 70 (ENGINE CONTROLS - TESTS W/CODES - 4.3L)DIAGNOSTIC TROUBLE CODESDTC U1192 - LOSS OF VTD (PASS-LOCK(R))/EVO COMMUNICATIONDIAGNOSTIC PROCEDURES
1997 Chevrolet Chevy Express G3500, Van Cargo, 6.5 F
Diagnostic Procedures
1997 Chevrolet Chevy Express G3500, Van Cargo, 6.5 FSECTION Diagnostic Procedures
WARNING: This page is about a different car, the 1998 GMC Savana, 1998 GMC Forward Control, 1998 Chevrolet Forward Control, 1998 Chevrolet Chevy Van, and 1998 Chevrolet Chevy Express. However, it is still accessible from the selected car via links, so may be relevant.
- Perform POWERTRAIN ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK , then go to next step.
- Using scan tool, check if scan tool can communicate with Vehicle Theft Deterrent (VTD) system. If scan tool can communicate with VTD, go to next step. If scan tool cannot communicate with VTD, see ANTI-THEFT SYSTEM article in ACCESSORIES/SAFETY EQUIPMENT section.
- Using scan tool, select Active Transfer Case (ATC) function. Check if DTC is stored in ATC memory. If DTC is stored, see ANTI-THEFT SYSTEM article in ACCESSORIES/SAFETY EQUIPMENT section. If DTC is not stored, go to next step.
- Check for short or open in Class II serial data circuit between VCM and VTD. Check for faulty connections at DLC, VCM or ATC. Repair as necessary. After repairs, go to step 6). If circuit or connections are okay, go to next step.
- Reconnect all components previously disconnected. Using scan tool, clear DTCs. Turn ignition off for 15 seconds. Turn ignition on, engine off. Check if DTC resets. If DTC resets, go to step 8). If DTC does not reset, go to step 7).
- Repair circuit as necessary. After repairs, go to step 9).
- DTC is intermittent. Check for additional DTCs. If additional DTCs are set, diagnose affected DTCs. If no additional DTCs are set, system is okay. See DIAGNOSTIC AIDS.
- Replace VCM. Program replacement VCM using required equipment and perform VTD and Crankshaft Variation Learn Procedure. After replacing VCM, go to next step.
- Turn ignition off. Reconnect all disconnected components. Using scan tool, clear all DTCs. Check if DTC resets. If DTC resets, repeat step 1). If DTC does not reset, system is okay.
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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.