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Home >> Ford >> 2018 >> Expedition MAX SSV, 4WD >> Repair and Diagnosis (Single Page) >> Transmission >> Transmission Control Systems >> Four-Wheel Drive Systems >> Description And Operation >> Four-Wheel Drive Systems - System Operation and Component Description >> System Operation >> IWE System >> IWE System Vacuum Diagram
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IWE System Vacuum Diagram

GFD293916Courtesy of FORD MOTOR COMPANY
Item Description
1 Air cleaner outlet pipe
2 Brake booster
3 Intake manifold
4 IWE vacuum reservoir
5 IWE solenoid
6 IWE vacuum actuator LH
7 IWE vacuum actuator RH
8 Vacuum solenoid valve
9 Filter
10 Venturi
11 Aspirator assembly

The IWE system consists of the following:

1 IWEs (spring-loaded vacuum hubs)
2 Vacuum hoses
3 IWE solenoid
4 Vacuum reservoir
GFD293917Courtesy of FORD MOTOR COMPANY

The IWE system uses a vacuum solenoid and vacuum actuated hubs to engage or disengage the front wheel hubs from the front half shafts.

When the 4WD system is in 2WD (2H) mode, the TCCM supplies a ground path to the IWE solenoid to apply engine vacuum to the IWEs thus disengaging the front hubs from the front half shafts. To maintain vacuum during all modes of engine operation, a one way vacuum check valve and a vacuum reservoir are positioned between the vacuum source and the IWE solenoid.

When operating in any 4WD mode, the TCCM does not supply the ground path to the IWE solenoid. Vacuum is not applied to the IWE. An internal spring keeps the IWE clutch ring engaging the front hub and the front half shaft.