Automatic Disconnecting Differential (ADD)

NOTE: First judge that the malfunction is found in the Automatic Differential Disengagement (ADD) control system or in the 2 - 4 selector system.

Automatic Disconnecting Differential (ADD) Control System:

1. Inspect the clutch hub and the clutch sleeve, performing the following.
a. Check the wear and damage of the clutch hub and clutch sleeve.If necessary, replace them.





b. Check that clutch sleeve slides smoothly on the clutch hub.





2. Using a feeler gauge, measure the clearance between the sleeve fork and clutch sleeve. The maximum clearance is 0.35 mm (0.0138 inch). If the clearance exceeds the maximum, replace the fork or sleeve.
3. Inspect the A.D.D. actuator, doing these steps.





a. Check that the sleeve fork moves to the actuator side when a vacuum of 66.7 kPa (19.69 inch Hg) is applied to port A. Also check that the vacuum remains constant, if it not, replace the actuator.





b. Check that the sleeve fork moves away from the actuator when a vacuum of 66.7 kPa (19.69 inch Hg) is applied to port B. Also check that the vacuum remains constant, if not, replace the actuator.

4. Inspect the A.D.D. solenoids by doing these procedures.





a. Using an ohmmeter, measure the resistance of the solenoids. The resistance should be 37 - 44 OHM.





b. Connect the battery to the solenoid. Check that air flows from the port E to port F. Check that air does not flow from the port E to the air filter.





c. Disconnect the battery positive voltage from the solenoid. Check that air flows from the port E to the air filter. Check that air does not flow from the port E to port.








5. Inspect the A.D.D. relay continuity
6. Inspect the A.D.D. switch.





a. Using an ohmmeter, check that there is continuity between terminals when the switch is pushed (differential connected position).
b. Using an ohmmeter, check that there is no continuity when the switch is free (differential disconnected position).

7. Inspect the transfer four wheel drive switch.