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Home >> Cadillac >> 1991 >> Seville Base >> Repair and Diagnosis >> Accessories & Equipment >> Gauges & Instrument Panels >> Instrument Panel - Electronic >> Testing >> Fuel Tank Sending Unit Test

Fuel Tank Sending Unit Test

  1. Disconnect fuel tank sending unit connector. Turn ignition switch to RUN position. Using a voltmeter, measure voltage between connector terminal "C" (Pink/Black wire) and ground. If battery voltage is present, go to next step. If battery voltage is not present, check Pink/Black wire for an open circuit.
  2. Using a voltmeter, measure voltage between connector terminals "C" (Pink/Black wire) and "E" (Black/White wire). If battery voltage is present, go to next step. If battery voltage is not present, check Black/White wire for an open circuit.
  3. Using a voltmeter, measure voltage between connector terminals "C" (Pink/Black wire) and "F" (Purple wire). If battery voltage is present, check Purple wire for a short to ground. If wire is okay, go to next step. If battery voltage is not present, check Purple wire for an open circuit or short to battery. If wire is okay, go to next step.
  4. Connect a fused jumper wire between fuel tank sending unit connector terminals "C" (Pink/Black wire) and "F" (Purple wire). Enter diagnostics, and select BCM data test BD40.
  5. To enter BCM diagnosis, turn ignition switch to ON position. Simultaneously depress OFF and WARM buttons on CCDIC.
  6. Continue to depress OFF and WARM buttons until all segments and bulbs of instrument cluster and CCDIC illuminate. When all segments are lit, system has entered self-diagnostic mode. Release OFF and WARM buttons. Trouble code display can be by-passed at any time by depressing FAN DOWN button.
  7. After trouble codes have been by-passed, SERVICE MODE system can be directed to perform specific system diagnostic tests. Display desired system (BCM) by depressing FAN DOWN button. Select desired system (BCM) by depressing FAN UP button.
  8. After diagnostic system has been selected for testing, select DATA? test. To advance display, depress FAN DOWN button. When desired test type is displayed (BD40), depress FAN UP button. After test type selection, depress FAN DOWN or FAN UP button as necessary to access appropriate test.
  9. If BCM displays approximately 25 and fuel display indicates a full tank, replace fuel tank sending unit. If BCM does not display correctly and fuel display does not indicate a full tank, check Purple wire for a short to ground. If Purple wire is okay, replace BCM.
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