{"model":"mk4","model_name":"MK4 Supra","vehicle":"Toyota Supra A80 (1993–2002, 2JZ-GE / 2JZ-GTE)","document":"Repair Manual","section":"TGE","section_name":"Troubleshooting 2JZ-GE","page":77,"pages_in_section":105,"title":"Dtc 78 Fuel Pump Control Circuit","section_header":"Engine — 2JZ-GE Engine Troubleshooting","ocr_text":"EG–457\nENGINE – 2JZ–GE ENGINE TROUBLESHOOTING\n\nDTC 78 Fuel Pump Control Circuit\nCIRCUIT DESCRIPTION\nThe fuel pump speed is controlled at 2 steps (high speed, low speed) by the condition of the engine (starting,\nlight load, heavy load), when the engine starts (STA ON), the engine control module sends a Hi signal (battery\npositive voltage) to the fuel pump ECU (FPC terminal).\nThe fuel pump ECU then outputs Hi voltage (battery positive voltage) to the fuel pump so that the fuel pump\noperates at high speed.\nAfter the engine starts, during idling or light loads, the engine control module outputs a Low signal (about 9 V)\nto the fuel pump ECU, the fuel pump ECU outputs Lo battery voltage (about 9 V) to the fuel pump and causes\nthe fuel pump to operate at low speed.\nIf the intake air volume increases (high engine load), the engine control module sends a Hi signal to the fuel\npump ECU and causes the fuel pump to operate at high speed.\n\nDTC No. | Diagnostic Trouble Code Detecting Condition | Trouble Area\n\n78\n(1) Open or short in fuel pump circuit for\n1 sec. Or more with engine speed\n1,000 rpm or less\n(2 trip detection logic)*\n2) Open in input circuit of fuel pump ECU\n(FPC) with engine speed 1,000 rpm or\nless\n(2 trip detection logic)*\n(3) Open or short in diagnostic signal line (DI)\nof fuel pump ECU with engine speed\n1,000 rpm or less\n(2 trip detection logic)*\n• Open or short in fuel pump ECU circuit\n• Fuel pump ECU\n• Engine control module power source circuit\n• Fuel pump\n• Engine control module\n\n*: See page EG–397.\n\nWIRING DIAGRAM\nEngine Control Module\nB+\nGR\nB-R\n5  B-R  10\nIB1       IC2\nGR  8   24\nEA1   E13   M-REL\nB-R\n3 EA3\nB-R\n4 Fuel Pump ECU\n+B\n5V\nB-R 12\n+B\nFP\nData Link\nConnector 1\nFPC  V-W  11   V-W  4    22\nIC2        IJ1   E10   FPC\nR/B\nNo.2\nL-R  8   L-R  7   L-R  FP\nIJ1       IC2\nB+\nDI  G  12   G   12  G   21  DI\n2   IC2     IJ1  E13\nE1\nB-Y\nR/B\nNo.2\nEFI No.1\nW-B\n2A\nB\nBattery\nSP1\nFuel Pump\nL  4\nE\nW-B\n2 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transcript of a scanned Toyota factory manual page; verify critical values (torque specs, part numbers) against the image."}