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Is the resistance greater than 10,000 ohms?
Yes
REPLACE the GEM; REFER to
Section 419-10
. CLEAR the DTCs. TEST the system for
normal operation.
No
REPAIR circuit 605 (R). CLEAR the DTCs. TEST the system for normal operation.
C23
CHECK THE VACUUM AT THE 4WD AND 2WD VACUUM SOLENOIDS
Verify the vacuum (with the engine running) at the feed lines on the 2WD and 4WD vacuum
solenoids.
Is approximately 10 in Hg (25A cm Hg) of vacuum present?
Yes
GO to
C24
.
No
REPAIR the vacuum feed line in question. CLEAR the DTCs. TEST the system for normal
operation.
C24
CHECK THE 4WD AND 2WD VACUUM SOLENOIDS — CLOSED
Connect Vacuum Pump to the feed line of the vacuum solenoid being tested.
Monitor the GEM PIDs 2WDSOL and 4WDSOL while triggering the GEM active commands
AXLE ENGG and AXLE DSCN to OFF.
Apply vacuum and verify the vacuum solenoids are closed.
Are the solenoids closed?
Yes
RELEASE the applied vacuum. GO to
C25
.
No
REPLACE the vacuum solenoid in question. CLEAR the DTCs. TEST the system for normal
operation.
C25
CHECK THE 4WD AND 2WD VACUUM SOLENOIDS — OPEN
Page 58 of 74
1998 F-150/250 Workshop Manual
1/11/2011
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