GM Service Manual Online
For 1990-2009 cars only

Tools Required

    • J 23688 Coolant Tester (Fahrenheit Scale)
    • J 26568 Coolant Tester (Centigrade Scale)

Do not remove the clear plastic pump from J 23688 or J 26568 .


    Object Number: 201982  Size: SH
  1. Release the tip of the pump from the coolant tester housing.
  2. Insert the tip of the pump into the surge tank.
  3. Ensure the tip of the of the pump is below the level of coolant.

  4. Press and release the bulb in order to get a sample.
  5. Insert the tip of the pump into the cover plate opening.
  6. Important: Do not open the plastic cover when taking readings because water evaporation can change the readings.

  7. Press the bulb and allow a few drops to fall onto the measuring surface.

  8. Object Number: 13713  Size: SH
  9. Point J 23688 or J 26568 toward any light and look into the eyepiece.
  10. • Coolant protection reading is at the point where the dividing line between light and dark crosses the scale.
    • The temperature scale is reversed from a standard thermometer scale.
    • Below zero readings are on the upper half of the scale.

    Object Number: 13712  Size: SH
  11. If the readings are not clear, the measuring surface was not cleaned and dried properly.
  12. Wipe the tester dry and repeat the test.