1991 1999 ford explorer chilton User Manual

							
4-WHEEL ANTI-LOCK BRAKE SYSTEM (4WABS)
Introduction
This system is used on the Mountaineer and 1993-99 Explorer, it was optional on all 1995-99 4-wheel drive
Ranger models.
The 4WABS system consists of the following components: The anti-lock Hydraulic Control Unit (HCU)-mounted to a bracket which is bolted to the left-hand
inner fender.
1. 
The Explorer/Mountaineer 4WABS module-located on the outboard side of the left-hand inner
fender, behind the plastic fender liner.
2. 
The Ranger 4WABS module-located in front and to the right of the battery, on the radiator support.
3. 
The front wheel sensors - bolted to the steering knuckles (4x2) or, on Explorer/Mountaineer (4x4)
they are part of the wheel bearing assembly and on Ranger (4x4) they are part of the front axle
assembly.
4. 
The rear speed sensor-located on the rear axle housing.
5. 
The front speed sensor indicator rings-located on the front rotor assemblies (4x2) or, on Ranger they
are pressed into the front wheel hub and spindle and on Explorer/Mountaineer (4x4) are integral in the
front wheel bearing assemblies.
6. 
The rear speed sensor indicator rings-located on the ring gear inside the rear axle housing.
7. 
The Explorer/Mountaineer G-switch-located on the left-hand frame rail aft of the No. 2
crossmember.
8. 
The Ranger G-switch-located on the left-hand frame rail forward of the No. 3 crossmember.
9. 
The Explorer/Mountaineer main and pump motor relay-located in a four relay box mounted near the
battery on the left fender wall.
10. 
The Ranger main and pump motor relay-located in a two relay box mounted near the master cylinder
on the left cowl side.
11. 
System Self-Test
The 4WABS module performs system tests and self-tests during startup and normal operation. The valve,
sensor and fluid level circuits are monitored for proper operation. If a fault is found, the 4WABS will be
deactivated and the amber ANTI LOCK light will be lit until the ignition is turned OFF. When the light is lit,
the Diagnostic Trouble Code (DTC) may be obtained. Under normal operation, the light will stay on for about
2 seconds while the ignition switch is in the ON position and will go out shortly after.
The Diagnostic Trouble Codes (DTC) are an alphanumeric code and a scan tool, such as Rotunda NGS Tester
007-00500, is required to retrieve the codes. The DTC code chart has been included.
4-WHEEL ANTI-LOCK BRAKE SYSTEM (4WABS) 1063 
						

							4-Wheel Anti-lock Brake System (4WABS) diagnostic trouble code chart
Click to enlarge
Hydraulic Control Unit (HCU)
PUMP TESTING Disconnect the HCU pump motor electrical plug.
1. 
Connect a Digital Volt/Ohm Meter (DVOM) across the two pump terminals and record the reading.
2. 
The reading should be between 52-68 Ohms
3. 
If not, replace the pump motor.
4.  HOW TO USE THIS BOOK
1064 System Self-Test 
						

							
REMOVAL & INSTALLATION
Front end of the 4-wheel ABS systemClick to enlarge
Disconnect the battery ground cable.
1. 
Unplug the 8-pin connector from the unit, and the 4-pin connector from the pump motor.
2. 
Disconnect the 5 inlet and outlet tubes from the unit. Immediately plug the ports.
3. 
Remove the 3 unit attaching nuts and lift out the unit.
4. 
Installation is the reverse of removal. Torque the mounting nuts to 12-18 ft. lbs. and the tube fittings
to 10-18 ft. lbs.
5. 
After reconnecting the battery, it may take 10 miles or more of driving for the Powertrain Control
Module to relearn its driveability codes.
Bleed the brakes.
6. 
Electronic Control Unit
REMOVAL & INSTALLATION Disconnect the battery ground cable.
1. 
Unplug the wiring from the ECU.
2. 
Remove the mounting bolts, slide the ECU off its bracket.
3.  HOW TO USE THIS BOOK
REMOVAL & INSTALLATION 1065 
						

							Installation is the reverse of removal. Torque the mounting screw to 5-6 ft. lbs. and the connector bolt
to 4-5 ft. lbs.
4. 
After reconnecting the battery, it may take 10 miles or more of driving for the Powertrain Control
Module to relearn its driveability codes.
Front Wheel Speed Sensor
TESTING Disconnect the speed sensor wire harness plug from the sensor or sensor pigtail.
1. 
Connect a Digital Volt/Ohm Meter (DVOM) across the two sensor terminals and record the reading.
2. 
The reading should be within the following ranges for the appropiate model and sensor.
3. 
Ranger Front right sensor-1.0-1.4 k Ohms
· 
Front left sensor-1.0-1.4 k Ohms
· 
Explorer/Mountaineer-4x4 models only Front right sensor-0.270-0.330 k Ohms
· 
Front left sensor-0.270-0.330 k Ohms
· 
REMOVAL & INSTALLATION Inside the engine compartment, disconnect the sensor from the harness.
1. 
Unclip the sensor cable from the brake hose clips.
2. 
Remove the retaining bolt from the spindle and slide the sensor from its hole.
3. 
Installation is the reverse of removal. Torque the retaining bolt to 40-60 inch lbs.
4. 
Rear Speed Sensor
TESTING Remove the rear wheel speed sensor from the axle housing.
1. 
Connect a Digital Volt/Ohm Meter (DVOM) across the two sensor terminals and record the reading.
2. 
The reading should be between 0.8 and 1.4 k Ohms.
3. 
If not, replace the sensor.
4. 
REMOVAL & INSTALLATION HOW TO USE THIS BOOK
1066 REMOVAL & INSTALLATION 
						

							Rear wheel speed sensor-4-wheel ABS
Click to enlarge
Disconnect the wiring from the harness.
1. 
Remove the sensor hold-down bolt and remove the sensor from the axle.
2. 
To install: Thoroughly clean the mounting surfaces. Make sure no dirt falls into the axle. Clean the magnetized
sensor pole piece. Metal particles can cause sensor problems. Replace the O-ring.
3. 
Coat the new O-ring with clean engine oil.
4. 
Position the new sensor on the axle. It should slide into place easily. Correct installation will allow a
gap of 0.005-0.045 in.
5. 
Torque the hold-down bolt to 25-30 ft. lbs.
6. 
Connect the wiring.
7. 
Front Speed Sensor Ring HOW TO USE THIS BOOK
REMOVAL & INSTALLATION 1067 
						

							
REMOVAL & INSTALLATION
Front wheel sensor ring-4-wheel ABSClick to enlarge
Raise and support the front end on jackstands.
1. 
Remove the wheels.
2. 
Remove the caliper, rotor and hub.
3. 
Using a 3-jawed puller, remove the ring from the hub. The ring cannot be reused; it must be replaced.
4. 
To install: Support the hub in a press so that the lug studs do not rest on the work surface.
5. 
Position the newsensor ring on the hub. Using a cylindrical adapter 98mm ID X 106mm OD, press
the ring into place. The ring mustbe fully seated!
6. 
The remainder of installation is the reverse of removal.
7. 
Rear Speed Sensor Ring
REMOVAL & INSTALLATION
The ring is located on the differential case inside the axle housing. Once it is pressed off the case it cannot be
reused. This job should be left to a qualified service technician as it requires the rear differential to be
disassembled.
Chilton® Automotive Information Systems. © 2004 Thomson Delmar Learning. HOW TO USE THIS BOOK
1068 REMOVAL & INSTALLATION 
						

							
SPECIFICATION CHARTS
4-Wheel Anti-lock Brake System (4WABS) diagnostic trouble code chart Click to enlarge
Chilton® Automotive Information Systems. © 2004 Thomson Delmar Learning.
SPECIFICATION CHARTS 1069 
						

							
EXTERIOR
Doors
REMOVAL & INSTALLATION
Exploded view of the Ranger front door hinge assemblyClick to enlarge
EXTERIOR 1071 
						

							Exploded view of the Explorer/Mountaineer front door hinge assembly
Click to enlarge
HOW TO USE THIS BOOK
1072 REMOVAL & INSTALLATION 
						

							Exploded view of the Explorer/Mountaineer rear door hinge assembly
Click to enlarge
If replacing the door with a stripped unit, remove all usable components from the old door.
1. 
If removing the rear door (Explorer), remove the scuff plate and center panel trim panel. Remove the
upper and lower hinge access cover plate if equipped, and matchmark the hinge-to-body and
hinge-to-door location. Support the door either on jackstands or have somebody hold it for you.
2. 
Remove the lower hinge-to-door bolts.
3. 
Remove the upper hinge-to-door bolts and lift the door off the hinges.
4. 
If the hinges are being replaced, remove them from the door pillar.
5. 
To install: If they were removed, install the hinges in the same position as before removal. Tighten the bolts
finger tight.
6.  HOW TO USE THIS BOOK
REMOVAL & INSTALLATION 1073