GM Service Manual Online
For 1990-2009 cars only

Coolant testers J 26568 Centigrade Scale or J 23688 Fahrenheit Scale can be used to check the antifreeze protection of the coolant. Make sure the refractometer markings are correct. Unless J 26568 or J 23688 has a provision for temperature correction, test the temperature at which testers are calibrated. If the coolant is warmer or cooler the reading may be incorrect. Follow the manufacturer's directions on the tester being used.

    • Before each use, lift up the plastic cover at the slanted end of J 26568 or J 23688 exposing the measuring window and the bottom of the plastic cover.
    • Wipe the window with a tissue or a clean soft cloth.
    • Close the plastic cover.

Testing

Tools Required

J 26568 or J 23688 Coolant Tester

Do not remove the clear plastic pump from the tester.

  1. Release the tip of the pump from the coolant tester housing.

  2. Object Number: 13709  Size: SH
  3. Insert the tip of the pump into the surge tank/radiator. The tip of the pump must be below the level of the coolant.
  4. Press the bulb. Release the pump bulb in order to obtain a sample of the coolant.
  5. Bend the tube around the J 26568 or the J 23688 . Insert the tip of the pump into the cover plate opening.
  6. Press the pump bulb. Allow a few drops to fall onto the measuring surface. Do not open the plastic cover when taking readings because any water evaporation will change the reading.

  7. Object Number: 13713  Size: SH
  8. Point the coolant tester toward any light source. Look into the eyepiece.
  9. 6.1. The coolant protection reading is at the point where the dividing line between light and dark crosses the scale. Antifreeze protection is the scale on the right.
    6.2. The temperature scale is reversed from a standard thermometer scale.
    6.3. Below zero readings are on the upper half of the scale.
    6.4. If the readings are not clear, properly clean and dry the measuring surface. Conduct a new test. Make sure there is enough fluid on the measuring surface.