Land Rover Discovery: Fog Lamps

PRINCIPLES OF OPERATION

For a detailed description of the Fog Lamps, refer to the relevant Description and Operation section in the workshop manual. REFER to: Exterior Lighting (417-01, 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

3. If an obvious cause for an observed or reported concern is found, correct the cause (if possible) before proceeding to the next step
4. 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
5. 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:

Front fog lamp(s) inoperative

POSSIBLE CAUSE:

• Body system fault
• Lighting control switch fault
• Front fog lamp circuit short circuit to ground, short circuit to power, open circuit, high resistance
• Front fog lamp LED failed

ACTION:

• Using the manufacturer approved diagnostic system, check the central junction box for related DTCs and refer to the relevant DTC index
• Install a new lighting control switch
• Refer to the electrical circuit diagrams and check the front fog lamp circuit for short circuit to ground, short circuit to power, open circuit, high resistance
• Install a new front fog lamp

SYMPTOM:

Rear fog lamp(s) inoperative

POSSIBLE CAUSE:

• Body system fault
• Lighting control switch fault
• Rear fog lamp circuit short circuit to ground, short circuit to power, open circuit, high resistance
• Rear fog lamp LED failed

ACTION:

• Using the manufacturer approved diagnostic system, check the central junction box for related DTCs and refer to the relevant DTC index
• Install a new lighting control switch
• Refer to the electrical circuit diagrams and check the rear fog lamp circuit for short circuit to ground, short circuit to power, open circuit, high resistance
• Install a new rear fog lamp

SYMPTOM:

Front fog lamp(s) dim

POSSIBLE CAUSE:

• Body system fault
• Lighting control switch fault
• Rear fog lamp circuit short circuit to ground, short circuit to power, open circuit, high resistance
• Rear fog lamp LED failed

ACTION:

• Using the manufacturer approved diagnostic system, check the central junction box for related DTCs and refer to the relevant DTC index
• Install a new lighting control switch
• Refer to the electrical circuit diagrams and check the rear fog lamp circuit for short circuit to ground, short circuit to power, open circuit, high resistance
• Install a new rear fog lamp

SYMPTOM:

Front fog lamp(s) dim

POSSIBLE CAUSE:

• Body system fault
• Front fog lamp circuit high resistance
• Front fog lamp LED failed

ACTION:

• Using the manufacturer approved diagnostic system, check the central junction box for related DTCs and refer to the relevant DTC index
• Refer to the electrical circuit diagrams and check the front fog lamp circuit for high resistance
• Install a new front fog lamp

SYMPTOM:

Rear fog lamp(s) dim

POSSIBLE CAUSE:

• Body system fault
• Rear fog lamp circuit high resistance
• Rear fog lamp bulb incorrect specification
• Rear fog lamp LED failed

ACTION:

• Using the manufacturer approved diagnostic system, check the central junction box for related DTCs and refer to the relevant DTC index
• Refer to the electrical circuit diagrams and check the rear fog lamp circuit for high resistance
• Install a new rear fog lamp bulb
• Install a new rear fog lamp

SYMPTOM:

Warning indicator(s) inoperative

POSSIBLE CAUSE:

• Body system fault
• Instrument cluster fault
• Lighting control switch fault

ACTION:

• Using the manufacturer approved diagnostic system, check the central junction box for related DTCs and refer to the relevant DTC index
• Using the manufacturer approved diagnostic system, check the instrument cluster for related DTCs and refer to the relevant DTC index
• Install a new lighting control switch

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: Diagnostic Trouble Code (DTC) Index - DTC: Central Junction Box (CJB) (100-00, Description and Operation).

• Exterior Lighting Front Fog Lamp Adjustment
• Front Fog Lamp (G1785314) Removal and Installation

Interior Lighting / Diagnosis and TestingExterior Lighting Front Fog Lamp Adjustment

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