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.
  1. Perform powertrain diagnostic system check. See POWERTRAIN DIAGNOSTIC SYSTEM CHECK  under SELF-DIAGNOSTIC SYSTEM. After performing diagnostic system check, go to next step.
  2. Turn ignition on, with engine off. Using scan tool, with throttle closed, observe APP sensor voltages. APP 1 sensor voltage should be .45-.95 volt. APP 2 sensor voltage should be 4.0-4.5 volts. APP 3 sensor voltage should be 3.6-4.0 volts. If voltages are as specified, go to next step. If voltages are not as specified, go to step  4.
  3. Problem is intermittent. If no additional DTCs are set, see DIAGNOSTIC AIDS . If any additional DTCs are set, perform appropriate DTC test. See DIAGNOSTIC TROUBLE CODE DEFINITIONS .
  4. Turn ignition off. Disconnect APP sensor harness connector. Turn ignition on. Measure voltage between ground and 5-volt reference circuits at APP sensor harness connectors (terminals "D", "E" and "G"). See Figure. If voltage on all circuits is 4.75 volts, go to next step. If voltage on all circuits is not 4.75 volts, go to step  6.
  5. Turn ignition on. Using test light connected to battery positive, probe ground circuits at APP sensor harness connectors (terminals "A", "B" and "J"). If test light illuminates on all circuits, go to step  9. If test light does not illuminate on all circuits, go to step  8.
  6. Turn ignition off. Disconnect PCM harness connectors. Check for open or short to ground in 5-volt reference circuits. Repair as necessary. After repairs, go to step  11. If circuits are okay, go to next step.
  7. Check 5-volt reference circuits for poor connections at PCM harness connector. Repair as necessary. After repairs, go to step  11. If connections are okay, go to step  10.
  8. Turn ignition off. Disconnect PCM harness connectors. Check for open in ground circuits. Repair as necessary. After repairs, go to step  11. If circuits are okay, go to step  10.
  9. Turn ignition off. Replace APP sensor. After repairs, go to step  11.
  10. Replace PCM. Perform PCM relearn procedure. See POWERTRAIN CONTROL MODULE  under PROGRAMMING. After repairs, go to next step.
  11. 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 P0226. 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.
  12. 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.
RENDER: 1.0x

NO RELATED

Recommended Tools & Savings

Use the Manual With the Right Hardware

Pair factory procedures with proven DIY tools so the instructions are easier to execute.

Affiliate disclosure: We may earn a commission at no extra cost to you.

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.