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Home >> GMC >> 1998 >> Forward Control 6.5 F >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - System & Component Testing - 6.5L Turbo Diesel >> Fuel System >> Fuel Heater Diagnosis
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Fuel Heater Diagnosis

  1. If water in fuel light is operating properly, go to next step. If water in fuel light is not operating properly, repair water in fuel light as necessary. See WATER IN FUEL LIGHT DIAGNOSIS .
  2. Disconnect fuel heater harness connector and remove heater from filter housing. With fuel heater temperature greater than 50°F (10°C), apply battery voltage between fuel heater terminals. Observe heater element. If heat does not exist, go to next step. If heat exists, go to step 4).
  3. Cool fuel heater to less than 46°F (8°C). Connect fuel heater to battery voltage as in step 2). Observe heater element. If heat does not exist, go to next step. If heat exists, go to step 5).
  4. Replace fuel heater and go to next step.
  5. Check fuel heater power circuit (Pink wire) for open or short, between ENG 1 fuse and fuel heater. If open or short does not exist, go to next step. If open or short exists, repair as necessary.
  6. Check ground circuit (Black wire) for open. If open exists, repair as necessary. If open does not exist, system is okay at this time.
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