GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Chevrolet 🢒 1997 🢒 Venture 🢒 Engine 🢒 Engine Cooling 🢒 Coolant Concentration Testing

Tools Required
    • J 23688
    • J 26568

Caution: This vehicle is equipped with a Supplemental Inflatable Restraint (SIR) System. Failure to follow the correct procedure could cause the following conditions:

   • Air bag deployment
   • Personal injury
   • Unnecessary SIR system repairs
In order to avoid the above conditions, observe the following guidelines:
   • Refer to SIR Component Views in order to determine if you are performing service on or near the SIR components or the SIR wiring.
   • If you are performing service on or near the SIR components or the SIR wiring, disable the SIR system. Refer to Disabling the SIR System.


    Object Number: 1392 Size: SH

    Important: Both J 23688 and J 26568

  1. Make sure that the eyepiece of the J 23688 or the J 26568
    2. 1.1. Before each use, swing the plastic cover at the slanted end of the J 23688 J 26568 .
    1.2. Use a tissue or clean soft cloth to wipe dry both the prism and the bottom of the sample cover.
    1.3. Close the plastic cover.
  2. Release the tip of the pump from the J 23688 or the J 26568 .

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

  3. Remove the radiator cap.

    4. Object Number: 1393 Size: SH
  4. Insert the tube into the coolant recovery reservoir.

    5. Make sure that the tube is below the level of the coolant.

  5. Press and release the bulb in order to get a sample of the coolant.
  6. Bend the tube around the J 23688 or the J 26568 .

    7. Important: Do not open the plastic cover when taking readings. 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
  8. Point the J 23688 or the J 26568 .
    9. • The coolant protection reading is at the point where the dividing line between light and dark crosses the scale on the right.
    • The temperature scale is reversed from a standard thermometer scale.
    • (Below zero readings are on the upper half of the scale.)
    • If readings are unclear, the measuring prism was not dried, or there was not enough fluid on the measuring prism.

Calibrating The Testers

J 23688 and J 26568 are factory calibrated and should not require adjustment. If adjustment is required, follow the directions below.

  1. Make sure that the J 23688 or the J 26568 is between 21 and 29°C (70 and 85°F).
  2. Take a reading using distilled water.

    3. If the reading is not 0°C (32°F), correct the coolant tester by adjusting the screw on the bottom.

    Important: Do not remove the screw from the J 23688 or the J 26568 .

  3. Remove the sealant covering the screw.
  4. Turn the screw in the direction necessary in order to adjust the reading to the 0°C (32°F) line.
  5. Use a silicone sealant in order to reseal the screw.