Test R: Rear Axle Hydraulic System Malfunction

1996 Ford Explorer 4D Utility, 4.0 X, 4WD, AutomaticSECTION Test R: Rear Axle Hydraulic System Malfunction

  1. Check Brakelines

    - Visually inspect brakelines from valve block to rear wheels for damage and correct installation. Repair or replace as necessary. If brakeline is okay, go to next step.
  2. Check Rear Axle Outlet Valve

    - Turn ignition off. Install Breakout Box (014-00322) with proper overlay. Using a jumper wire, connect breakout box test pins No. 1, 19, 27 and 33. Raise rear of vehicle. Using an assistant, press hard on brake pedal while attempting to turn either rear axle wheel. If wheel turns, or brake pedal drops slowly, replace Hydraulic Control Unit (HCU). Bleed hydraulic system. If wheel does not turn and brake pedal does not drop slowly, go to next step.
  3. Check Valve Operation

    - Continue applying pressure on brake pedal. Turn ignition on while attempting to turn either rear wheel. DO NOT leave ignition on for more than 30 seconds. If wheel now turns, outlet valve is okay and test is complete. If wheel does not turn, replace HCU.
RENDER: 1.0x

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When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

  • β€’ You smell fuel, burning insulation, or see smoke.
  • β€’ Brakes feel soft, pull hard to one side, or make grinding noises.
  • β€’ The engine overheats, stalls repeatedly, or misfires under load.
  • β€’ You are missing required tools, torque specs, or safe lifting equipment.
  • β€’ You are not confident in the next step or safety outcome.