A4WD question
Postmaster
Joined: Jan 2009
Posts: 4,584
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From: Chesapeake, Va.
Send me a PM with your email and i'll e some pages from my manual. I think you are on the right track.
SECTION 205-03: Front Drive Axle/Differential 1998 Expedition/Navigator Workshop Manual
IN-VEHICLE REPAIR
Vacuum Reservoir —Auxiliary
Removal
Remove the front fender splash shield (16103) ; refer to Section 414-01 .
Disconnect the vacuum harness from the auxiliary vacuum reservoir and the A/C vacuum reservoir.

Slide the vacuum reservoir assembly out of the battery tray.

Separate the A/C vacuum reservoir from the auxiliary vacuum reservoir.

Installation
Follow the removal procedure in reverse order.
SECTION 205-03: Front Drive Axle/Differential 1998 Expedition/Navigator Workshop Manual
IN-VEHICLE REPAIR
Vacuum Reservoir —Auxiliary
Removal
Remove the front fender splash shield (16103) ; refer to Section 414-01 .
Disconnect the vacuum harness from the auxiliary vacuum reservoir and the A/C vacuum reservoir.

Slide the vacuum reservoir assembly out of the battery tray.

Separate the A/C vacuum reservoir from the auxiliary vacuum reservoir.

Installation
Follow the removal procedure in reverse order.
Temporarily Deactivated
Joined: Aug 2009
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If the 4H works then it is unlikely the vacuum system is at fault because it must be working to engage 4H.
If you have a flashing warning, no 4wd engagement in A4WD, I would be checking the speed sensors on the t-case. If one is bad it will not know when to operate the 4wd shift motor. That is probably the cause of the flashing light.
If you have a flashing warning, no 4wd engagement in A4WD, I would be checking the speed sensors on the t-case. If one is bad it will not know when to operate the 4wd shift motor. That is probably the cause of the flashing light.
Senior User
Joined: Jan 2008
Posts: 420
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From: New Hampshire
If the 4H works then it is unlikely the vacuum system is at fault because it must be working to engage 4H.
If you have a flashing warning, no 4wd engagement in A4WD, I would be checking the speed sensors on the t-case. If one is bad it will not know when to operate the 4wd shift motor. That is probably the cause of the flashing light.
If you have a flashing warning, no 4wd engagement in A4WD, I would be checking the speed sensors on the t-case. If one is bad it will not know when to operate the 4wd shift motor. That is probably the cause of the flashing light.
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Postmaster
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Junior User
Joined: Dec 2010
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From: Michigan
If the 4H works then it is unlikely the vacuum system is at fault because it must be working to engage 4H.
If you have a flashing warning, no 4wd engagement in A4WD, I would be checking the speed sensors on the t-case. If one is bad it will not know when to operate the 4wd shift motor. That is probably the cause of the flashing light.
If you have a flashing warning, no 4wd engagement in A4WD, I would be checking the speed sensors on the t-case. If one is bad it will not know when to operate the 4wd shift motor. That is probably the cause of the flashing light.
My question is this: Are the wires I swapped into the new t/c motor the "speed sensors" you speek of? And if so, which set operates the A4WD? (View from the t/c motor) The 3 to the left, three to the right, or the single tan wire on the upper right? Also, are they easy to replace and if so how are they attached to the t/c?
Or is the A4WD speed sensor on the rear axle, and if so, where? Thanks guys.
Postmaster
Joined: Jan 2009
Posts: 4,584
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From: Chesapeake, Va.
I have always (8 years) had the same blinking A4WD issue with my 98' Expedition EB. This year I had a vacuum leak which prevented 4x4HI engagement. My first thought was the t/c motor so I replaced it. Obviously it did nothing until I repaired the vacuum leak. My 4x4 works again, but I still have the blinks in A4WD
My question is this: Are the wires I swapped into the new t/c motor the "speed sensors" you speek of? And if so, which set operates the A4WD? (View from the t/c motor) The 3 to the left, three to the right, or the single tan wire on the upper right? Also, are they easy to replace and if so how are they attached to the t/c?
Or is the A4WD speed sensor on the rear axle, and if so, where? Thanks guys.
My question is this: Are the wires I swapped into the new t/c motor the "speed sensors" you speek of? And if so, which set operates the A4WD? (View from the t/c motor) The 3 to the left, three to the right, or the single tan wire on the upper right? Also, are they easy to replace and if so how are they attached to the t/c?
Or is the A4WD speed sensor on the rear axle, and if so, where? Thanks guys.
Junior User
Joined: Dec 2010
Posts: 62
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From: Michigan
Thank you Moto Mel and Alwaysford...............I'm sorry I may not have been too clear. I do want to know "where on the truck" the speed sensors are located. Is the sensor the wires that come out of, or are they connected to, the t/c? Or are they on the rear axle as some have suggested?
Also, any idea on price and where to get them?
Also, any idea on price and where to get them?
Postmaster
Joined: Jan 2009
Posts: 4,584
Likes: 3
From: Chesapeake, Va.
Thank you Moto Mel and Alwaysford...............I'm sorry I may not have been too clear. I do want to know "where on the truck" the speed sensors are located. Is the sensor the wires that come out of, or are they connected to, the t/c? Or are they on the rear axle as some have suggested?
Also, any idea on price and where to get them?
Also, any idea on price and where to get them?
Junior User
Joined: Dec 2010
Posts: 62
Likes: 0
From: Michigan
That's not too bad. My question remains, where are they located on the vehicle?
Fleet Owner
Joined: Apr 2008
Posts: 24,316
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From: 0,0,1
There's one at each of the front wheels and one at the top center of the rear differential.