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HOMESERVICE MANUALSMERCURY2010MARINER HYBRID, AWDREPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT CARSECTION 1074 (CRUISE CONTROL SYSTEM)DIAGNOSTIC TESTSSPEED CONTROLPINPOINT TESTSPINPOINT TEST B: THE SET SPEED FLUCTUATESPINPOINT TEST B: THE SET SPEED FLUCTUATES
2010 Mercury Mariner Hybrid, AWD

Pinpoint Test B: The Set Speed Fluctuates

2010 Mercury Mariner Hybrid, AWDSECTION Pinpoint Test B: The Set Speed Fluctuates
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.
CAUTION: Use the correct probe adapter(s) when making measurements. Failure to use the correct probe adapter(s) may damage the connector.
  1. B1 CHECK THE SPEED CONTROL CABLE/THROTTLE BODY LINKAGE 
    • Key in OFF position.
    • Visually inspect the speed control cable connections, the throttle body linkage, and the speed control actuator pulley cover.
    • Are the speed control cable connections, the throttle body linkage, and the speed control actuator pulley cover OK?  
    1. YES  : Go to  B2.
    2. NO  : INSTALL a new speed control cable or REPAIR the throttle body linkage. To install a new speed control cable, REFER to Speed Control Cable . TEST the system for normal operation. For repair of the throttle body linkage, REFER to ACCELERATION CONTROL article. TEST the system for normal operation. For repair of the speed control actuator pulley cover, INSTALL the cover correctly. TEST the system for normal operation.
  2. B2 CHECK THE SPEEDOMETER OPERATION 
    • Drive the vehicle and observe the speedometer operation.
    • Does the speedometer needle fluctuate? 
    1. YES  : REFER to INSTRUMENT CLUSTER (IC), MESSAGE CENTER, AND WARNING CHIMES article.
    2. NO  : Go to  B3.
  3. B3 CHECK FOR A BASE ENGINE CONCERN 
    • Drive the vehicle and determine if there is a base engine concern.
    • Is a base engine concern present? 
    1. YES  : REFER to the Introduction - Gasoline Engines article.
    2. NO  : Go to  B4.
  4. B4 CHECK THE VEHICLE SPEED SIGNAL VOLTAGE 
    CAUTION: Make sure the vehicle is secured correctly before attempting to place the transmission range selector lever in DRIVE (D) or in 1st gear if equipped with a manual transaxle.
    • Disconnect: Speed Control Actuator C122
    • Disconnect: Active Torque Coupling C3254 (if equipped)
    • Raise the vehicle on a hoist. REFER to JACKING AND LIFTING article.
      • NOTE: For vehicles with a manual transaxle, place the transaxle into 1st gear.
    • Start the vehicle, place the transaxle in DRIVE (D) and with the engine at idle allow all of the drive wheels to spin.
    • Measure and record the AC voltage between the speed control actuator C122-3, circuit VMC05 (VT/OG), harness side and ground with the vehicle drive wheels spinning a minimum of 8 km/h (5 mph).
      • Fig 1: Checking Vehicle Speed Signal Voltage
      GF0010779Courtesy of FORD MOTOR CO.
    • Apply the brakes until the drive wheels come to a stop. Place the transaxle in PARK (P), fully engage the parking brake and turn the engine off.
    • Is the AC voltage greater than 4.5 volts? 
    1. YES  : Go to  B5.
    2. NO  : Go to  B6.
  5. B5 CHECK THE VEHICLE SPEED SIGNAL FREQUENCY 
    CAUTION: Make sure the vehicle is secured correctly before attempting to place the transmission range selector lever in DRIVE (D) or in 1st gear if equipped with a manual transaxle.
      NOTE: For vehicles with a manual transaxle, place the transaxle into 1st gear.
    • Start the vehicle, place the transaxle in DRIVE (D) and with the engine at idle allow all of the drive wheels to spin.
    • Measure and record the frequency between the speed control actuator C122-3, circuit VMC05 (VT/OG), harness side and ground with the vehicle drive wheels spinning a minimum of 8 km/h (5 mph). Record the speedometer reading.
      • Fig 2: Checking Vehicle Speed Signal Frequency
      GF0025547Courtesy of FORD MOTOR CO.
    • Apply the brakes until the drive wheels come to a stop. Place the transaxle in PARK (P), fully engage the parking brake and turn the engine off.
    • Divide the frequency reading by 2.2 to get a mph result and compare this to the reading of the speedometer (example: 10 mph = 22 Hz).
    • Does the frequency reading result match the speedometer reading? 
    1. YES  : INSTALL a new speed control actuator. REFER to Speed Control Actuator . TEST the system for normal operation.
    2. NO  : Go to  B6.
  6. B6 CHECK FOR CORRECT PCM OPERATION 
    • Disconnect the PCM connector.
    • Check for:
      • corrosion
      • damaged pins
      • pushed-out pins
    • Connect the PCM connector and make sure it seats correctly.
    • Operate the system and verify the concern is still present.
    • Is the concern still present? 
    1. YES  : INSTALL a new PCM. REFER to ELECTRONIC ENGINE CONTROLS - 2.3L article or ELECTRONIC ENGINE CONTROLS - 3.0L (4V) article. TEST the system for normal operation.
    2. NO  : The system is operating correctly at this time. The concern may have been caused by a loose or corroded connector.
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.
  • • You are not confident in the next step or safety outcome.