The 4-Wheel Anti-lock Brake System (ABS) used on 1995-96 Econoline models is an electronically operated, all wheel brake control system. Major components include the master cylinder, vacuum power brake booster, ABS Control Module, Hydraulic Control Unit (HCU) and various control sensors and switches.
The brake system is a three channel design. The front brakes are controlled individually and the rear brakes in tandem.
The system is designed to retard wheel lockup during periods of high wheel slip when braking. Retarding wheel lockup is accomplished by modulating fluid pressure to the wheel brake units.
- Hydraulic Control Unit (HCU) is located in the front left-hand frame inboard liner just under the driver's seat.
- Anti-lock brake control module is located on the fuel filter bracket which is mounted on the left-hand inboard frame in front of the fuel tank.
- Two front brake anti-lock sensors are located on the steering knuckles.
- Speed sensor indicator rings are pressed onto the backsides of the rotors.
- Rear axle speed sensor is integrated into the rear axle housing.
- Stoplight switch is attached to the brake pedal.
- ABS relay is located in the power distribution box.
- Pump motor relay is located in the power distribution box.
The ABS 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 ABS 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 or its equivalent, is required to retrieve the codes. Refer to the manufacturers instructions for operating the tool and retrieving the codes.