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Home >> Suzuki >> 1999 >> Grand Vitara JS, Automatic >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - Self-Diagnostics >> Diagnostic Tests >> DTC P0451: Evaporative (EVAP) Control System Pressure Sensor Performance >> Diagnosis & Repair Procedure
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Diagnosis & Repair Procedure

  1. If not using scan tool, go to next step. If using scan tool, turn ignition off. Connect scan tool to Data Link Connector (DLC). Remove fuel filler cap. Turn ignition on. Observe FUEL TANK PRESS reading on scan tool. If fuel tank pressure does not measure approximately zero kPa, go to step  3 . If fuel tank pressure measures approximately zero kPa, problem exists with fuel tank pressure control system. Test fuel tank pressure control system. See FUEL EVAPORATION in SYSTEM & COMPONENT TESTING article. If fuel tank pressure control system checks okay, replace PCM. See REMOVAL, OVERHAUL & INSTALLATION article. Retest system.
  2. If diagnosing without scan tool, remove fuel filler cap. Remove PCM cover, located below right side of instrument panel. Connect DVOM (backprobe) between PCM 35-pin connector "A" terminals No. 20 (Brown/Red wire) and No. 32 (Gray/Yellow wire). Turn ignition on. If 2.0-2.5 volts does not exist, go to next step. If 2.0-2.5 volts exists, test fuel tank pressure control system. See FUEL EVAPORATION in SYSTEM & COMPONENT TESTING article. If fuel tank pressure control system checks okay, replace PCM. See REMOVAL, OVERHAUL & INSTALLATION article. Retest system.
  3. Disconnect 12-pin fuel tank pressure sensor harness connector, located in left rear corner of vehicle. Connect DVOM between 12-pin fuel tank pressure sensor harness connector terminals No. 7 (Gray/Yellow wire) and No. 8 (Gray/Red wire). Turn ignition on. If 4.5-5.5 volts exists, go to next step. If 4.5-5.5 volts does not exist, go to step  6 .
  4. Check for open or short in Brown/Red wire between 12-pin fuel tank pressure sensor harness connector terminal No. 6 and PCM 35-pin connector "A" terminal No. 20. See WIRING DIAGRAMS article. Repair as necessary. If Brown/Red wire is okay, check for open in wiring between 12-pin fuel tank pressure sensor harness connector (located in left rear corner of vehicle) and 3-pin fuel tank pressure sensor harness connector, located at fuel tank. If wiring between 12-pin fuel tank pressure sensor harness connector and 3-pin fuel tank pressure sensor harness connector is okay, go to next step.
  5. Test fuel tank pressure control system. See FUEL EVAPORATION in SYSTEM & COMPONENT TESTING article. If fuel tank pressure control system checks okay, replace PCM. See REMOVAL, OVERHAUL & INSTALLATION article. Retest system.
  6. Check for open or short in Gray/Red wire or Gray/Yellow wire between 12-pin fuel tank pressure sensor harness connector and PCM 35-pin connector "A". Repair as necessary. If Gray/Red wire and Gray/Yellow wire are okay, replace PCM. See REMOVAL, OVERHAUL & INSTALLATION article. Retest system.
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