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 P0370: TIMING REFERENCE HIGH RESOLUTIONDIAGNOSTIC 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.
- Turn ignition off. Disconnect fuel temperature/optical camshaft sensor harness connector (located on fuel injection pump). Turn ignition on. Measure voltage between ground and optical fuel/temperature sensor harness connector terminal "A" (Gray wire). See Figure. If voltage is 4.8-5.2 volts, go to next step. If voltage is not 4.8-5.2 volts, go to step 6.
- Leave fuel temperature/optical camshaft sensor harness connector disconnected. Using test light connected to battery positive, probe fuel temperature/optical camshaft sensor harness connector terminal "F" (Pink/Black wire). If test light illuminates, go to next step. If test light does not illuminate, go to step 7.
- Reconnect fuel temperature/optical camshaft sensor harness connector. Start and operate engine as close to conditions indicated on FREEZE FRAME/FAILURE RECORDS. Using scan tool, select DTC, SPECIFIC, and then enter DTC P0370. If scan tool displays "LAST TEST FAILED" message, go to next step. If "LAST TEST FAILED" message is not displayed, see DIAGNOSTIC AIDS .
- Maintain engine speed at point of failure as indicated in step 4) . Using DVOM set to Hz scale, backprobe PCM harness connector C2 terminal A2 (Orange wire). See HIGH RESOLUTION SIGNAL SPECIFICATIONS table. If DVOM reading is within 100 Hz of specified value relating to RPM, go to step 16. If DVOM reading is not within 100 Hz of specified value relating to RPM, go to step 9.
- Turn ignition off. Disconnect PCM harness connectors. Check for open, short to ground or short to sensor ground circuit in Gray wire between fuel temperature/optical camshaft harness connector terminal "A" and PCM harness connector C1 terminal D14. Repair as necessary. After repairs, go to step 19. If circuit is okay, go to step 8.
- Turn ignition off. Check for open in Pink/Black wire to PCM harness connector C1 terminal D9 or check poor connection at PCM harness connector. Repair as necessary. After repairs, go to step 19. If circuit and connection are okay, go to step 18.
- Check Gray wire for poor connection at PCM harness connector C1 terminal D14. Repair as necessary. After repairs, go to step 19. If connection is okay, go to step 18.
- Turn ignition off. Disconnect fuel temperature/optical camshaft sensor harness connector. Turn ignition on. Using DVOM connected to ground, probe fuel temperature/optical camshaft sensor harness connector terminal "C" (Orange wire). If voltage is 4.8-5.2 volts, go to step 13. If voltage is not 4.8-5.2 volts, go to next step.
- If voltage range is greater than 4.8-5.2 volts, go to next step. If voltage range is not greater than 4.8-5.2 volts, go to step 12.
- Turn ignition off. Repair short to battery/ignition voltage in Orange wire. After repairs, go to step 17.
- Turn ignition off. Disconnect PCM harness connectors. Check for open, short to ground or short to sensor ground circuit in Orange wire to PCM harness connector C2 terminal A2. Repair as necessary. After repairs, go to step 19. If circuit is okay, go to step 16.
- Using DVOM set to milliamp (mA) scale, measure current between fuel temperature/optical camshaft sensor harness connector terminals "C" (Orange wire) and "F" (Pink/Black wire). If reading is less than 25 mA, go to step 15. If reading is not less than 25 mA, go to next step.
- Turn ignition off. Repair short between Orange and Pink/Black wires in fuel temperature/optical camshaft harness. After repairs, go to step 19.
- Turn ignition off. Check high resolution signal circuit (Orange wire) for poor connection at injection pump. Repair as necessary. After repairs, go to step 19. If connection is okay, go to step 17.
- Turn ignition off. Disconnect PCM harness connectors. Check for poor connection at PCM harness connector C2 terminal A2 (Orange wire). Repair as necessary. After repairs, go to step 19. If connection is okay, go to step 18.
- Replace injection pump. After replacement, new pump must be timed. See appropriate ON-VEHICLE ADJUSTMENTS article. After repairs, go to step 19.
- 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 P0370. 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.
HIGH RESOLUTION SIGNAL SPECIFICATIONS
| RPM | Hertz (Hz) |
|---|---|
| 700 | 2987 |
| 800 | 3413 |
| 900 | 3840 |
| 1000 | 4267 |
| 1100 | 4693 |
| 1200 | 5120 |
| 1300 | 5547 |
| 1400 | 5973 |
| 1500 | 6400 |
| 1600 | 6827 |
| 1700 | 7253 |
| 1800 | 7680 |
| 1900 | 8170 |
| 2000 | 8533 |
| 2100 | 8960 |
| 2200 | 9387 |
| 2300 | 9813 |
| 2400 | 10,240 |
| 2500 | 10,667 |
| 2600 | 11,093 |
| 2700 | 11,520 |
| 2800 | 11,947 |
| 2900 | 12,373 |
| 3000 | 12,800 |
| 3100 | 13,227 |
| 3200 | 13,653 |
| 3300 | 14,080 |
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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.