1, 2 Shift Solenoid, Timing Solenoid, and Lock-Up Solenoid Inspection

Fig 1: Inspecting Resistance Of Each Shift Solenoid To Ground

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Inspect the resistance of each shift solenoid between the terminal and the ground.

Fig 2: Identifying Minimum And Maximum Resistance Plot Lines (Shift, Timing And Lock-Up Solenoid)

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IMPORTANT: The resistance of the solenoid can become infinity ohm when the resistance measurement is made at high temperatures.

If the resistance value is not between the minimum and maximum resistance plot lines, then measure the solenoid resistance at 20°C (68°F).

Fig 3: Testing The Operation Of Shift Solenoid

Courtesy of GENERAL MOTORS CORP.

Test the operation of the shift solenoid. The shift solenoid is a normally open solenoid. Air will only pass through the solenoid when it is not energized.
Apply compressed air to the solenoid inlet.
If the solenoid does not allow air to pass thought the solenoid, replace the solenoid.
Apply B+ and Ground to the solenoid.
If the solenoid allows air to pass through the solenoid, then replace the solenoid (1).

Fig 4: Testing The Operation Of Timing Solenoid

Courtesy of GENERAL MOTORS CORP.

Test the operation of the timing solenoid. The timing solenoid is a normally closed solenoid (2). Air will only pass through the solenoid when the solenoid is energized.
Apply compressed air to the solenoid inlet.
If the solenoid allows air to pass through the solenoid, then replace the solenoid.
Apply B+ and Ground to the solenoid.
If the solenoid does not allow air to pass thought the solenoid, replace the solenoid.