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.
SYS.OK|MANUAL.DB● LIVE
HOMESERVICE MANUALSCHEVROLET2000CHEVY EXPRESS G3500, VAN PASSENGER, 7.4 JREPAIR AND DIAGNOSISENGINE PERFORMANCETESTING & DIAGNOSISENGINE CONTROLS - SYSTEM & COMPONENT TESTSENGINE SENSORS & SWITCHESMAP SENSOR CIRCUIT3.4L
2000 Chevrolet Chevy Express G3500, Van Passenger, 7.4 J
Map Sensor Circuit: 3.4L
2000 Chevrolet Chevy Express G3500, Van Passenger, 7.4 JSECTION 3.4L
- Perform On-Board Diagnostic (OBD) system check. See ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK in appropriate SELF-DIAGNOSTICS article. Go to next step.
- Check for the following:
- Missing or damaged MAP sensor seal.
- Damage, disconnected or misrouted vacuum hoses.
- Intake manifold vacuum leaks.
- Vacuum leaks at throttle body.
- Vacuum leaks in EGR system.
- Faulty, missing or incorrectly installed PCV valve.
If a problem does not exist, go to next step. If a problem exists, repair as necessary and go to step 14.
- Disconnect MAP sensor harness connector. Using scan tool, observe MAP sensor parameter. If zero volts is displayed, go to next step. If zero volts is not displayed, go to step 12.
- Using a test light connected to battery voltage, probe MAP sensor signal circuit (Light Green wire) at MAP sensor harness connector. See WIRING DIAGRAMS article. Observe MAP sensor parameter on scan tool. If 4.95 volts is displayed, go to next step. If 4.95 volts is not displayed, go to step 8.
- Using a fused jumper wire, connect MAP sensor signal circuit (Light Green wire) and MAP sensor reference voltage circuit (Gray wire) at MAP sensor harness connector. See WIRING DIAGRAMS article. Observe MAP sensor parameter on scan tool. If scan tool displays 4.95 volts, go to next step. If scan tool does not display 4.95 volts, go to step 7.
- Turn ignition off. Disconnect PCM harness connectors. Check MAP sensor ground circuit (Orange/Black wire) for open, high resistance or poor connection at PCM. If problem does not exist, go to step 10. If problem exists, repair as necessary and go to step 14.
- Check MAP sensor reference voltage circuit (Gray wire) for open, high resistance or poor connection at PCM. If problem does not exist, go to step 9. If problem exists, repair as necessary and go to step 14.
- Turn ignition off. Disconnect PCM harness connectors. Check MAP sensor signal circuit (Light Green wire) for open, high resistance, short to ground or short to sensor. If problem does not exist, go to next step. If problem exists, repair as necessary and go to step 14.
- Check MAP sensor signal circuit (Light Green wire) for poor connection at PCM. If problem does not exist, go to step 13. If problem exists, repair as necessary and go to step 14.
- Check for poor connection at MAP sensor. If problem does not exist, go to next step. If problem exists, repair as necessary and go to step 14.
- Replace MAP sensor. After repairs, go to step 14.
- Turn ignition off. Disconnect PCM harness connector. Turn ignition on. Check MAP sensor signal circuit (Light Green) for a short to voltage or short to MAP sensor reference voltage circuit (Gray wire). If problem does not exist, go to next step. If problem exists, repair as necessary and go to step 14.
- Replace PCM. Program PCM. Perform VTD password relearn procedure and crankshaft variation learn procedure. See COMPUTER RELEARN PROCEDURES article in GENERAL INFORMATION. After repairs, go to next step.
- Start engine and let idle. While observing MAP sensor parameter on scan tool, increase engine RPM. If MAP sensor value changes, system is okay. If MAP sensor value does not change, go to step 2.
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.