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Pinpoint Test A: The Speed Control Is Inoperative

WARNING: This page is about a different car, the 2009 Mercury Sable, 2009 Ford Taurus X, and 2009 Ford Taurus. 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. A1 VERIFY PCM CONFIGURATION 
    • Enter the following diagnostic mode on the diagnostic tool: Programmable Parameters
    • Verify that the speed control is enabled in the PCM.
    • Is the speed control enabled? 
    1. YES  : Go to  A2.
    2. NO  : ENABLE the speed control in the PCM using the scan tool programmable parameters menu. If no parameter exists, REFER to MODULE CONFIGURATION article to carry out programmable module installation (PMI). TEST the system for normal operation.
  2. A2 CHECK FOR DTCs 
    • Review the recorded DTCs from the PCM self-test.
    • Are any PCM DTCs recorded? 
    1. YES  : REFER to DTC Tables .
    2. NO  : Go to  A3.
  3. A3 CHECK THE SPEED CONTROL SWITCH 
    • Key in OFF position.
    • Disconnect: PCM C175b
    • Measure the resistance between the PCM C175b-56, circuit VES10 (WH), harness side and the PCM C175b-57, circuit RES08 (GN/BN), harness side while pressing the speed control switch buttons as follows:
      Speed Control Switch Resistance Value
      OFF Less than 5 ohms
      CANCEL 110 - 130 ohms
      SET- 276 - 324 ohms
      SET+ 552 - 648 ohms
      RESUME 1,021 - 1,199 ohms
      ON 1,941 - 2,278 ohms
      No switches pressed 3,965 - 4,655 ohms
      • Fig 1: Checking Speed Control Switch
      GF0004244Courtesy of FORD MOTOR CO.
    • Are the speed control switch resistance values OK? 
    1. YES  : Go to  A4.
    2. NO  : INSTALL a new speed control switch. REFER to Speed Control Switch . CLEAR the DTCs. REPEAT the self-test.
  4. A4 MONITOR THE TRANSMISSION RANGE (TR) PID 
    • Connect: PCM C175b
    • Key in ON position.
    • Enter the following diagnostic mode on the diagnostic tool: TCM DataLogger
    • Monitor the TCM TR PID.
    • Select DRIVE.
    • Does the PID value agree with the transmission range selector lever position? 
    1. YES  : Go to  A5.
    2. NO  : REFER to AUTOMATIC TRANSAXLE/TRANSMISSION - 6F50 article to continue diagnosis of the digital TR sensor.
  5. A5 CHECK THE PARKING BRAKE WARNING INDICATOR 
    • While observing the parking brake warning indicator, apply and release the parking brake.
    • Does the parking brake warning indicator operate correctly? 
    1. YES  : Go to  A6.
    2. NO  : REFER to INSTRUMENT CLUSTER (IC), MESSAGE CENTER, AND WARNING CHIMES article.
  6. A6 CHECK THE VEHICLE SPEED 
    NOTE: This step may require an assistant.
    • Enter the following diagnostic mode on the diagnostic tool: ABS DataLogger
    • Monitor and record the ABS module wheel speed (LF_WSPD) PID while driving the vehicle at 48 km/h (30 mph) as indicated on the speedometer.
    • Enter the following diagnostic mode on the diagnostic tool: PCM DataLogger
    • Monitor and record the PCM vehicle speed (VSS) PID while driving the vehicle at 48 km/h (30 mph) as indicated on the speedometer.
    • Does the speed indicated by the ABS module wheel speed PID match the PCM vehicle speed PID? 
    1. YES  : Go to Pinpoint Test B  to VERIFY the stoplamp switch circuits. If OK, go to  A7 .
    2. NO  : REFER to the Introduction - Gasoline Engines article to diagnose the output shaft (OSS) sensor signal.
  7. A7 CHECK FOR CORRECT PCM OPERATION 
    • Key in OFF position.
    • Disconnect all the PCM connectors.
    • Check for:
      • corrosion
      • damaged pins
      • pushed-out pins
    • Connect all the PCM connectors and make sure they are seated 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 article. CLEAR the DTCs. REPEAT the self-test.
    2. NO  : The system is operating correctly at this time. The concern may have been caused by a loose or corroded connector. CLEAR the DTCs. REPEAT the self-test.
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