Symptom Chart - Brake System

WARNING: This page is about a different car, the 2014 Lincoln MKX and 2014 Ford Edge. However, it is still accessible from the selected car via links, so may be relevant.

SYMPTOM DESCRIPTION - BRAKE SYSTEM

Condition	Possible Sources	Action
The red brake warning indicator and the yellow ABS warning indicator are illuminated	DTCs in the ABS module	REFER to ANTI-LOCK BRAKE SYSTEM (ABS) AND STABILITY CONTROL to diagnose the ABS.
The red brake warning indicator is always/never on	Brake fluid level switch Parking brake switch Wiring, terminals or connectors Instrument Cluster (IC) Smart Junction Box (SJB)	REFER to INSTRUMENTATION, MESSAGE CENTER, AND WARNING CHIMES to diagnose the red brake warning indicator.
Vehicle pulls or drifts during braking	Brake calipers and/or guide pins Brake flexible hose Brake pads Brake discs	INSPECT the brake system components. REFER to BRAKE SYSTEM INSPECTION .
	Tires	REFER to WHEELS AND TIRES to diagnose tire concerns.
	Suspension component(s) and/or wheel alignment	REFER to SUSPENSION SYSTEM - GENERAL INFORMATION to diagnose suspension system.
Brake pedal goes down fast or eases down slowly	Brake fluid leaks and/or air in the system	INSPECT the system for leaks. REPAIR as necessary. BLEED the system. REFER to BRAKE SYSTEM BLEEDING .
	Brake master cylinder	CARRY OUT the BRAKE MASTER CYLINDER - BYPASS CONDITION .
	Hydraulic Control Unit (HCU)	REFER to ANTI-LOCK BRAKE SYSTEM (ABS) AND STABILITY CONTROL to diagnose the HCU .
Brakes lock up under light brake pedal force	Brake pads Brake flexible hose Brake disc Brake calipers and/or guide pins	INSPECT the brake system components. REFER to BRAKE SYSTEM INSPECTION .
Brakes lock up under light brake pedal force	ABS	REFER to ANTI-LOCK BRAKE SYSTEM (ABS) AND STABILITY CONTROL to diagnose the ABS.
Excessive brake pedal travel (low/spongy pedal)	Brake fluid leaks and/or air in the system	INSPECT the system for leaks. REPAIR as necessary. BLEED the system. REFER to BRAKE SYSTEM BLEEDING .
	Brake master cylinder	CARRY OUT the BRAKE MASTER CYLINDER - BYPASS CONDITION .
	Brake calipers and/or guide pins	INSPECT the brake calipers and guide pins. REFER to BRAKE SYSTEM INSPECTION .
	Brake flexible hose	INSPECT the brake flexible hoses during brake application. REFER to BRAKE SYSTEM INSPECTION .
Erratic brake pedal travel	Brake pedal	INSPECT the brake pedal for binding, obstructions and correct connection to booster rod. REPAIR as necessary. CHECK the brake pedal fasteners for correct torque. REFER to SPECIFICATIONS .
Erratic brake pedal travel	ABS	REFER to ANTI-LOCK BRAKE SYSTEM (ABS) AND STABILITY CONTROL to diagnose the ABS.
Brake drag	Parking brake component	REFER to PARKING BRAKE AND ACTUATION to diagnose the parking brake system.
	Brake caliper and/or guide pins Brake flexible hose	INSPECT the brake system components. REFER to BRAKE SYSTEM INSPECTION .
	Brake booster Brake master cylinder	CARRY OUT the BRAKE MASTER CYLINDER - COMPENSATOR PORT .
	HCU	REFER to ANTI-LOCK BRAKE SYSTEM (ABS) AND STABILITY CONTROL to diagnose the HCU .
	Stoplamp switch	VERIFY correct installation of the stoplamp switch. REFER to EXTERIOR LIGHTING .
Excessive brake pedal effort	Insufficient vacuum for brake booster operation Brake booster manifold vacuum hose Brake booster Brake booster check valve	CARRY OUT the BRAKE BOOSTER .
Excessive brake pedal effort	Brake pads	INSPECT the brake pads. REFER to BRAKE SYSTEM INSPECTION .