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HOMESERVICE MANUALSCHEVROLET2001CHEVY EXPRESS G2500, VAN CARGO EXTENDED, 5.7 R, L31/KL8REPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT CARSECTION 124 (ENGINE CONTROL SYSTEM - TROUBLE SHOOTING - NO CODES)SYMPTOM DIAGNOSISHARD STARTSENSOR CHECKS
2001 Chevrolet Chevy Express G2500, Van Cargo Extended, 5.7 R, L31/KL8

Sensor Checks

2001 Chevrolet Chevy Express G2500, Van Cargo Extended, 5.7 R, L31/KL8SECTION Sensor Checks
WARNING: This page is about a different car, the 2003 Pontiac Vibe. However, it is still accessible from the selected car via links, so may be relevant.
  • Check the Engine Coolant Temperature (ECT) sensor using a scan tool to compare the engine coolant temperature with the ambient air temperature on a cold engine. If coolant temperature reading is more than 9°F (5°C) more or less than the ambient air temperature on a cold engine, check for high resistance in the coolant sensor circuit or in the sensor. See TEMPERATURE VS. RESISTANCE  table.
    TEMPERATURE VS. RESISTANCE

    °F °C Resistance - Ohms
    176 80 315
    158 70 435
    140 60 480
    122 50 810
    113 45 940
    104 40 1150
    95 35 1360
    86 30 1600
    77 25 2000
    68 20 2400
    59 15 3000
    50 10 3600
    41 5 4600
    32 0 5700
    23 -5 7400
    14 -10 9800
    5 -15 12700
    -4 -20 16000
  • Check the Throttle Position (TP) sensor. A sticking throttle shaft or a binding throttle linkage will causes a high TP sensor voltage. Under these conditions, PCM may not control the idle. Monitor the TP sensor angle with the scan tool. The indicated angle should be approximately 9-11 percent with throttle closed.
  • Inspect the Mass Air Flow (MAF) sensor operation. Run engine to normal operating temperature. Turn OFF all accessories and observe the MAF sensor at idle with a scan tool. If the MAF sensor reading is more than 3.5 g/s, see DTC P0101: MAF SENSOR PERFORMANCE under DIAGNOSTIC TESTS in SELF-DIAGNOSTICS - 1.8L VIBE article.
  • Check the Crankshaft Position (CKP) sensor engine reference signal with a scan tool. Observe ENGINE SPEED parameter while cranking the engine. The scan tool should indicate a steady 200-300 RPM while cranking. If erratic values, such as sudden spikes in the engine speed are displayed, the engine reference signal is not stable enough for the engine to start and run properly.
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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.