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HOMESERVICE MANUALSCHEVROLET1999CHEVY EXPRESS G1500, VAN CARGO, 5.7 RREPAIR AND DIAGNOSIS (SINGLE PAGE)ENGINE PERFORMANCESYSTEMENGINE CONTROL SYSTEM - TESTS W/CODES - DTC P0352-P0452DTC P0442DTC P0442: EVAP SYSTEM-SMALL LEAK DETECTED (5.7L "F" & "Y" BODIES)CIRCUIT DESCRIPTION
1999 Chevrolet Chevy Express G1500, Van Cargo, 5.7 R

Circuit Description

1999 Chevrolet Chevy Express G1500, Van Cargo, 5.7 RSECTION Circuit Description

PCM will test EVAP system for the following conditions:

  • Large and small leaks.
  • Excess vacuum.
  • Purge flow during non-commanded conditions.
  • Fuel pressure and fuel level sensor faults.
  • EVAP purge and vent valve faults.

PCM monitors the amount of vacuum in EVAP system by monitoring the fuel tank pressure sensor. For this DTC, PCM turns on both the EVAP purge and vent valves when conditions for setting this DTC are met. Engine vacuum is applied to closed EVAP system, checking whether vacuum can develop in EVAP system. Failure to develop vacuum may result from a large leak or from restriction. DTC will set after 2 consecutive failures during test.

Conditions for setting this DTC:

  • DTCs P0107, P0108, P0112, P0113, P0117, P0118, P0121, P0122, P0123, P0420, P0430, P0500, P0502, P0503, P0562, P0563, P1111, P1112, P1114, P1115, P1120, P1121, and HO2S related DTCs.
  • BARO pressure greater than 75 kPa.
  • Fuel level 15-85 percent of full capacity.
  • ECT and IAT is 39-86°F (4-30°C).
  • Start-up ECT and IAT within 16°F (9°C) of each other.
  • Vacuum in EVAP system decays (leaks) at too fast a rate.

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