Pinpoint Test F: Testing

WARNING: This page is about a different car, the 2007 Ford Pickup, 2007 Ford F550 Super Duty, 2007 Ford F450 Super Duty, and 2007 Ford Cab & Chassis. However, it is still accessible from the selected car via links, so may be relevant.

F1 CHECK THE BASE BRAKE COMPONENTS
- Visually inspect the brake lines from hydraulic control unit (HCU) to brake calipers.
- Visually inspect the calipers and brake components.
- Are any of these components damaged?
1. YES : REPAIR or INSTALL new components as necessary. TEST the system for normal operation.
2. NO : Go to F2.
F2 CHECK FOR A LEAKING DUMP VALVE
- Key in OFF position.
- Remove the rubber boots from the 2 HCU low pressure accumulators (LPA).
  
  Fig 1: Locating Rubber Boots (1 Of 2)
  Courtesy of FORD MOTOR CO.
- Insert a clean steel implement (paper clip or small screwdriver) into each LPA.
  
  Fig 2: Locating Rubber Boots (2 Of 2)
  Courtesy of FORD MOTOR CO.
- Key in START position.
  NOTE: A leaking dump valve is similar to the master cylinder bypass condition. It is important that the pedal be quickly and forcefully applied to rule out master cylinder bypass as a cause. Typically, master cylinder bypass occurs only at low pedal pressure rates.
- Have an assistant press hard on the brake pedal while observing the steel implements.
- Do any of the implements move out 6.35 mm (0.25 in) or more?
1. YES : INSTALL a new HCU. REFER to Hydraulic Control Unit (HCU) in this article.
2. NO : REMOVE the steel implements. INSTALL the rubber boots on each LPA. REFER to BRAKE SYSTEM - GENERAL INFORMATION article for diagnosis of the base brake system.