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HOMESERVICE MANUALSGMC1999FORWARD CONTROL 5.7 R, AUTOMATICREPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT CARSECTION 66 (AUTOMATIC TRANSMISSION SERVICING)LUBRICATIONCHECKING FLUID LEVEL & CONDITION (4L60-E)CHECKING FLUID CONDITION
1999 GMC Forward Control 5.7 R, Automatic

Checking Fluid Condition

1999 GMC Forward Control 5.7 R, AutomaticSECTION Checking Fluid Condition
WARNING: This page does not describe the selected car, but rather 6 other vehicles, including the 2002 GMC Savana Special, 2002 GMC Savana Camper Special, 2002 GMC Savana, 2002 Chevrolet RV Cutaway, and 2002 Chevrolet Cutaway. However, it is still accessible from the selected car via links, so may be relevant.
  1. Check the fluid color. Is the fluid Red in color? If so, go to step  5 . If not, go to next step.
  2. Is the fluid a non-transparent Pink in color? If so, go to step  14 . If not, go to next step.
    3. NOTE: Fluid may turn a Dark Brown in color from normal use. This does not always indicate an oxidation or a contamination issue.
  3. Is the fluid a Light Brown in color? If so, go to step  5 . If not, go to next step.
  4. Is the fluid Black in color and or have a burnt smell? If so, go to step  14 . If not, go to next step.
  5. Does the fluid appear as a solid liquid and not foamy or full of bubbles on level indicator? If so, go to next step. If not, go to step  7 .
  6. Check the fluid level. Proper level should be in middle of the "X" pattern, on level indicator. Is the level okay? If so, go to step  19 . If not, go to next step.
  7. Is the fluid level high on indicator? If so, go to step  12 . If not, go to next step.
  8. Is the fluid level low on indicator? If so, go to step  9 . If not, go to next step.
  9. Check for any external leak or leaks. Did you find an external leak or leaks? If so, go to next step. If not, go to step  11 .
  10. Correct leak or leaks as needed. Are any leak or leaks still present? If so, go to step  9 . If not, go to next step.
  11. Add fluid until level is in middle of "X" pattern on the level indicator. Is the level okay? If so, go to step  19 . If not, go to step  6 .
  12. Drain fluid until level is in middle of "X" pattern on the level indicator. Is level okay? If so, go to step  19 . If not, go to step  6 .
  13. Replace oil cooler and flush lines. See AUXILIARY OIL COOLER  under REMOVAL & INSTALLATION. Is the replacement complete? If so, go to step  15 .
    14. NOTE: A small amount of friction material in pan bottom is a normal condition, but large pieces and or metal particles will require complete transmission overhaul.
  14. Drain fluid and remove oil pan to inspect. Is there sign or signs of internal component damage noted in bottom of transmission oil pan? If so, go to step  16 . If not go to step  13 .
  15. Replace the filter and fluid. See DRAINING & REFILLING  . Is the replacement complete? If so, go to step  6 .
  16. Flush oil cooler and lines and check flow. See OIL COOLER FLUSHING  and TRANSMISSION & OIL COOLER FLOW CHECK  . Is the oil cooler flushing and flow test complete? If so, go to step  17 .
  17. Overhaul transmission. See appropriate OVERHAUL article in AUTOMATIC TRANSMISSIONS. Is the overhaul procedure complete? If so, go to next step.
  18. Add new fluid. Is the procedure complete? If so, go to step  6 .
  19. Check the fluid level and correct as necessary. Is the fluid level satisfactory? If so, system is okay. If not, go to step  1 .
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When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

  • • You smell fuel, burning insulation, or see smoke.
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  • • The engine overheats, stalls repeatedly, or misfires under load.
  • • You are missing required tools, torque specs, or safe lifting equipment.
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