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 MANUALSCHEVROLET2001CHEVY EXPRESS G2500, VAN CARGO EXTENDED, 5.7 R, L31/KL8REPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT VARIANT/TRIMSECTION 1 (ENGINE CONTROLS SELF-DIAGNOSTICS - 6.5L)DIAGNOSTIC TESTSDTC P1641: MALFUNCTION INDICATOR LIGHT CONTROL CIRCUITDIAGNOSTIC PROCEDURES
2001 Chevrolet Chevy Express G2500, Van Cargo Extended, 5.7 R, L31/KL8
Diagnostic Procedures
2001 Chevrolet Chevy Express G2500, Van Cargo Extended, 5.7 R, L31/KL8SECTION Diagnostic Procedures
WARNING: This page is about a different variant/trim than selected.
- Perform powertrain diagnostic system check. See POWERTRAIN DIAGNOSTIC SYSTEM CHECK under SELF-DIAGNOSTIC SYSTEM. After performing diagnostic system check, go to next step.
- Start and operate engine at idle. Using scan tool, command MIL on and off. If MIL illuminates, go to next step. If MIL does not illuminate, go to step 4.
- Problem is intermittent. If other DTCs are set, perform appropriate DTC test. See DIAGNOSTIC TROUBLE CODE DEFINITIONS . If no other DTCs are set, see DIAGNOSTIC AIDS .
- Turn ignition off. Disconnect PCM harness connector C3. Turn ignition on. If MIL does not illuminate, go to next step. If MIL illuminates, go to step 7.
- Turn ignition on. Connect fused jumper wire between ground and PCM harness connector C3 terminal C14 (Brown/White wire). See Figure or Figure . If MIL illuminates, go to next step. If MIL does not illuminate, go to step 8.
- Turn ignition off. Check for poor connections at PCM harness connector. Repair as necessary. After repairs, go to step 10. If connections are okay, go to step 9.
- Repair short to voltage in Brown/White wire between MIL and PCM harness connector C3 terminal C14. After repairs, go to step 10.
- Turn ignition off. Check for open in Pink wire between MIL and instrument panel fuse/relay block. Check for faulty MIL bulb. Check for open or short to battery voltage in Brown/White wire between MIL and PCM. Repair as necessary. After repairs, go to step 10.
- Replace PCM. Perform PCM relearn procedure. See POWERTRAIN CONTROL MODULE under PROGRAMMING. After repairs, go to next step.
- Turn ignition on, with engine off. Using scan tool, clear DTCs. Start and warm engine to normal operating temperature. Select DTC, SPECIFIC, and then enter DTC P1641. Operate vehicle within the conditions for setting DTC. See CODE ENABLE CRITERIA . If scan tool indicates that this test ran and passed, go to next step. If scan tool does not indicate that this test ran and passed, go to step 2.
- Using scan tool, check for DTCs. If any undiagnosed DTCs are set, perform appropriate DTC test. See DIAGNOSTIC TROUBLE CODE DEFINITIONS . If no DTCs are set, 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.