Land Rover Discovery Owners & Service Manuals

Land Rover Discovery: Speed Control Speed Control / Diagnosis and Testing

PRINCIPLES OF OPERATION

For a detailed description of the Speed Control system, refer to the relevant Description and Operation section in the workshop manual. REFER to: Speed Control (310-03 Speed Control, Description and Operation).

INSPECTION AND VERIFICATION

CAUTION:

Diagnosis by substitution from a donor vehicle is NOT acceptable.

Substitution of control modules does not guarantee confirmation of a fault, and may also cause additional faults in the vehicle being tested and/or the donor vehicle.

NOTES:

  • If a control module or a component is suspect and the vehicle remains under manufacturer warranty, refer to the Warranty Policy and Procedures manual, or determine if any prior approval programme is in operation, prior to the installation of a new module/component.
  • When performing voltage or resistance tests, always use a digital multimeter accurate to three decimal places, and with an up-todate calibration certificate. When testing resistance always take the resistance of the digital multimeter leads into account.
  • Check and rectify basic faults before beginning diagnostic routines involving pinpoint tests.
  1. Verify the customer concern
  2. Visually inspect for obvious signs of damage and system integrity

Visual Inspection

Visual Inspection

  1. If an obvious cause for an observed or reported concern is found, correct the cause (if possible) before proceeding to the next step
  2. If the cause is not visually evident, verify the symptom and refer to the Symptom Chart, alternatively check for Diagnostic Trouble Codes (DTCs) and refer to the DTC Index
  3. Check DDW for open campaigns. Refer to the corresponding bulletins and SSMs which may be valid for the specific customer complaint and carry out the recommendations as required

SYMPTOM CHART

SYMPTOM CHART

SYMPTOM:

Speed control inhibited/disabled

POSSIBLE CAUSES:

  • Steering wheel switchpack fault
  • Engine system fault
  • Anti-lock brake system fault

ACTION:

  • Check the operation of the speed control switches. Using the Jaguar Land Rover approved diagnostic equipment, check the body control module for related DTCs and refer to the relevant DTC index
  • Using the Jaguar Land Rover approved diagnostic equipment, check the powertrain control module for related DTCs and refer to the relevant DTC index
  • Using the Jaguar Land Rover approved diagnostic equipment, check the anti-lock brake system control module for related DTCs and refer to the relevant DTC index

SYMPTOM:

Unable to regulate/adjust vehicle speed

POSSIBLE CAUSES:

  • Steering wheel switchpack fault

ACTION:

  • Check the operation of the speed control switches. Using the Jaguar Land Rover approved diagnostic equipment, check the body control module for related DTCs and refer to the relevant DTC index

SYMPTOM:

Unable to cancel speed control from steering wheel

POSSIBLE CAUSES:

  • Steering wheel switchpack fault

ACTION:

  • Check the operation of the speed control switches. Using the Jaguar Land Rover approved diagnostic equipment, check the body control module for related DTCs and refer to the relevant DTC index

SYMPTOM:

Unable to cancel speed control from brake pedal

POSSIBLE CAUSES:

  • Brake pedal switch fault

ACTION:

  • Using the Jaguar Land Rover approved diagnostic equipment, check the anti-lock brake system control module for related DTCs and refer to the relevant DTC index

DTC INDEX

For a list of Diagnostic Trouble Codes (DTCs) that could be logged on this vehicle, please refer to Section 100-00. REFER to: (100-00 General Information)

Diagnostic Trouble Code Index - INGENIUM I4 2.0L Diesel, DTC: Engine Control Module (ECM) B10A2-07 to P034B-76 (Description and Operation), Diagnostic Trouble Code Index - GTDi 2.0L Petrol/GTDi 2.0L Petrol - SULEV, DTC: Engine Control Module (ECM) (Description and Operation), Diagnostic Trouble Code Index - INGENIUM I4 2.0L Diesel, DTC: Engine Control Module (ECM) B10A2-07 to P034B-76 (Description and Operation), Diagnostic Trouble Code Index - DTC: Central Junction Box (CJB) (Description and Operation), Diagnostic Trouble Code Index - DTC: Anti-lock Braking System Control Module (ABS) (Description and Operation).

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