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Home >> Lincoln >> 2009 >> MKZ FWD >> Repair and Diagnosis (Single Page) >> Brakes >> Traction Control >> Anti-Lock Brake System - Vehicle Dynamic Systems >> Diagnosis & Testing >> Anti-Lock Control >> Pinpoint Tests >> Pinpoint Test F: Poor Vehicle Tracking During Anti-Lock Function >> Pinpoint Test F: Poor Vehicle Tracking During Anti-Lock Function

Pinpoint Test F: Poor Vehicle Tracking During Anti-Lock Function

  1. F1 BLEED THE BRAKE SYSTEM 
    1. YES  : Go to  F2.
    2. NO  : The brake system is operating correctly. The concern may have been caused by air in the hydraulic system or a sticky valve.
  2. F2 CHECK THE ABS INLET VALVE (CLOSED POSITION) 
    • With the vehicle in NEUTRAL, position it on a hoist. Refer to JACKING AND LIFTING article.
    • Rotate all the wheels to make sure they rotate freely (the transaxle must be in NEUTRAL).
    • Connect the diagnostic tool.
    • Key in ON position.
    • Enter the following diagnostic mode on the diagnostic tool: ABS DataLogger: Left Front Inlet Valve (LF_INLET) Output Command
    • Toggle the LF_INLET output command ON.
    • Apply moderate brake pedal effort.
    • Have an assistant attempt to rotate the LF wheel.
    • Does the LF wheel rotate? 
    1. YES  : TOGGLE the LF_INLET output command OFF. Go to  F3.
    2. NO  : TOGGLE the LF_INLET output command OFF. INSTALL a new HCU. REFER to Hydraulic Control Unit (HCU) . TEST the system for normal operation.
  3. F3 CHECK THE ABS INLET VALVE (OPEN POSITION) 
    • Apply moderate brake pedal effort.
    • Have an assistant attempt to rotate the LF wheel.
    • Does the LF wheel rotate? 
    1. YES  : INSTALL a new HCU. REFER to Hydraulic Control Unit (HCU) . TEST the system for normal operation.
    2. NO  : Go to  F4.
  4. F4 CHECK THE ABS OUTPUT VALVE (OPEN POSITION) 
    • Apply moderate brake pedal effort.
    • Enter the following diagnostic mode on the diagnostic tool: ABS DataLogger
    • Toggle the left front inlet valve (LF_INLET) output command ON.
      • NOTE: Each activation of the output command will run the pump for 2 seconds.
    • Toggle the hydraulic pump motor (PMP_MOTOR) output command ON for 6 seconds (the trigger must be pressed 3 times).
    • Toggle the left front inlet valve (LF_OUTLET) output command ON, then toggle the LF_OUTLET output command. Repeat 3 times.
    • Have an assistant attempt to rotate the LF wheel.
    • Does the LF wheel rotate? 
    1. YES  : TOGGLE all output commands OFF. Go to  F5.
    2. NO  : TOGGLE all output commands OFF. INSTALL a new HCU. REFER to Hydraulic Control Unit (HCU) . TEST the system for normal operation.
  5. F5 CHECK THE ABS INLET AND OUTLET VALVE (CLOSED POSITION) 
    • Apply moderate brake pedal effort.
    • Have an assistant attempt to rotate the LF wheel.
    • Does the LF wheel rotate? 
    1. YES  : INSTALL a new HCU. REFER to Hydraulic Control Unit (HCU) . TEST the system for normal operation.
    2. NO  : Beginning with Step F2, REPEAT this procedure for the RF, LR and RR wheels using the appropriate output commands. If no failure occurs the system is operating normally.
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