Symptom Chart - Brake System

2009 Mercury Milan Premier, 3.0 1, AWDSECTION Symptom Chart - Brake System
WARNING: This page is about a different car, the 2008 Mercury Mariner and 2008 Ford Escape. However, it is still accessible from the selected car via links, so may be relevant.
Symptom Chart - Brake System

Condition Possible Sources Action
  • The red brake warning indicator and the yellow ABS warning indicator are illuminated
  • DTCs in the ABS module
  • The red brake warning indicator is illuminated and the yellow ABS warning indicator is not illuminated
  • Brake fluid level and/or brake fluid leaks
  • INSPECT the system for leaks, REPAIR as necessary. FILL the brake master cylinder reservoir to the MAX line.
 
  • Parking brake
  • MAKE SURE the parking brake is fully released. If it is fully released, go to Pinpoint Test A .
 
  • Wiring, terminals and connectors
  • Controller area network (CAN) communication system
  • Instrument cluster
  • Smart junction box (SJB)
  • The red brake warning indicator is inoperative
  • Wiring, terminals and connectors
  • Instrument cluster
  • Missing CAN communication
  • The brakes pull or drift
  • Tires
  • INSPECT the tires for uneven or excessive wear, and correct inflation. REFER to WHEELS AND TIRES article to diagnose the tires.
 
  • Brake pads
  • INSPECT the brake pads for contamination, uneven taper or excessive wear, REFER to Brake Pads .
 
  • Brake discs
 
  • Brake calipers and/or guide pins
 
  • Suspension component and/or wheel alignment
  • Brake pedal goes down fast
  • Brake fluid leaks and/or air in the system
  • INSPECT the system for leaks. REPAIR as necessary. FILL the brake master cylinder reservoir. BLEED the system. REFER to Brake System Bleeding .
 
  • Brake master cylinder
  • CARRY OUT the Brake Master Cylinder Component Test in this article.
 
  • Hydraulic control unit (HCU)
  • The brake pedal eases down slowly
  • Air in the system
 
  • Brake master cylinder
  • CARRY OUT the Brake Master Cylinder Component Test in this article.
 
  • HCU
  • Brakes lock up under light brake pedal force
  • Brake pads
  • INSPECT the brake pads for uneven taper or excessive wear, REFER to Brake Pads .
 
  • Brake shoes
  • INSPECT the brake shoes for excessive wear, REFER to Brake Shoes .
 
  • Brake calipers and/or guide pins
 
  • Brake shoes out of adjustment
  • REFER to DRUM BRAKE article for the brake shoe adjustment procedure.
 
  • Anti-lock brake control system
  • Excessive/erratic brake pedal travel
  • Brake fluid leaks and/or air in the system
  • INSPECT the system for leaks. REPAIR as necessary. FILL the brake master cylinder reservoir. BLEED the system. REFER to Brake System Bleeding .
 
  • Brake calipers and/or guide pins
 
  • Brake flexible hose
  • INSPECT the brake flexible hoses for swelling and damage. INSTALL new as necessary. REFER to DRUM BRAKE article for rear drum brakes, FRONT DISC BRAKE article for front disc brakes and REAR DISC BRAKE article for rear disc brakes.
 
  • Brake master cylinder
  • CARRY OUT the Brake Master Cylinder Component Test in this article.
 
  • Brake pads
  • INSPECT the brake pads for taper wear, REFER to Brake Pads .
 
  • Brake pedal
  • INSPECT the brake pedal for binding, obstructions and correct installation. REPAIR as necessary. CHECK the brake pedal fasteners for correct torque. REFER to Specifications in HYDRAULIC BRAKE ACTUATION article.
 
  • Anti-lock brake control system
  • Brakes drag
  • Parking brake component
 
  • Brake shoes out of adjustment
  • REFER to DRUM BRAKE article for the brake shoe adjustment procedure.
 
  • Brake caliper guide pins
  • INSPECT the caliper guide pins for correct operation. INSTALL new components as necessary. REFER to Brake Caliper Guide Pins .
 
  • Brake caliper(s)
  • REPAIR or INSTALL new brake calipers as necessary. REFER to FRONT DISC BRAKE article for front disc brakes or REAR DISC BRAKE article for rear disc brakes.
 
  • Wheel cylinder(s)
  • REPAIR or INSTALL new wheel cylinders as necessary. REFER to DRUM BRAKE article.
 
  • Brake booster
  • CARRY OUT the Brake Booster Component Test in this article.
 
  • Brake master cylinder
  • CARRY OUT the Brake Master Cylinder Component Test in this article.
 
  • Stoplamp switch
  • INSPECT the switch for correct installation. REINSTALL or INSTALL new as necessary. REFER to EXTERIOR LIGHTING article.
 
  • Speed control deactivator switch
  • INSPECT the switch for correct installation. REINSTALL or INSTALL new as necessary. REFER to SPEED CONTROL article.
  • Excessive brake pedal effort
  • Insufficient engine vacuum for brake booster operation
 
  • Brake booster manifold vacuum hose
  • VERIFY engine vacuum at the booster. REROUTE, REPAIR or INSTALL new components as necessary.
 
  • Brake booster
  • VERIFY engine vacuum at the booster. CARRY OUT the Brake Booster Component Test in this article.
 
  • Brake booster check valve
  • VERIFY engine vacuum at the booster. CARRY OUT the Check Valve Component Test in this article.
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:

  • You smell fuel, burning insulation, or see smoke.
  • Brakes feel soft, pull hard to one side, or make grinding noises.
  • The engine overheats, stalls repeatedly, or misfires under load.
  • You are missing required tools, torque specs, or safe lifting equipment.
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