Land Rover Discovery: Trailer Lamps

PRINCIPLES OF OPERATION

For a detailed description of the Trailer Lamps, refer to the relevant Description and Operation section in the workshop manual. REFER to: Exterior Lighting (417-01 Exterior Lighting, 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 that has the resolution ability to view 3 decimal places.

  For example, on the 2 volts range can measure 1mV or 2 K Ohm range can measure 1 Ohm. 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:

Trailer stop lamp(s) inoperative

POSSIBLE CAUSE:

• Body system fault
• Trailer stop lamp circuit short circuit to ground, short circuit to power, open circuit, high resistance

ACTION:

• Using the Jaguar Land Rover approved diagnostic equipment, check the central junction box for related DTCs and refer to the relevant DTC index
• Refer to the electrical circuit diagrams and check the trailer stop lamp circuit for short circuit to ground, short circuit to power, open circuit, high resistance. Repair the wiring harness as necessary

SYMPTOM:

Trailer stop lamp(s) dim

POSSIBLE CAUSE:

• Body system fault
• Trailer stop lamp circuit high resistance

ACTION:

• Using the Jaguar Land Rover approved diagnostic equipment, check the central junction box for related DTCs and refer to the relevant DTC index
• Refer to the electrical circuit diagrams and check the trailer stop lamp circuit for high resistance. Repair the wiring harness as necessary

SYMPTOM:

Trailer stop lamp(s) stuck on

POSSIBLE CAUSE:

• Body system fault
• Trailer stop lamp circuit short circuit to power

ACTION:

• Using the Jaguar Land Rover approved diagnostic equipment, check the central junction box for related DTCs and refer to the relevant DTC index
• Refer to the electrical circuit diagrams and check the trailer stop lamp circuit for short circuit to power. Repair the wiring harness as necessary

SYMPTOM:

Trailer fog lamp(s) inoperative

POSSIBLE CAUSE:

• Body system fault
• Trailer fog lamp circuit short circuit to ground, short circuit to power, open circuit, high resistance

ACTION:

• Using the Jaguar Land Rover approved diagnostic equipment, check the central junction box for related DTCs and refer to the relevant DTC index
• Refer to the electrical circuit diagrams and check the trailer fog lamp circuit for short circuit to ground, short circuit to power, open circuit, high resistance. Repair the wiring harness as necessary

SYMPTOM:

Trailer fog lamp(s) dim

POSSIBLE CAUSE:

• Body system fault
• Trailer fog lamp circuit high resistance

ACTION:

• Using the Jaguar Land Rover approved diagnostic equipment, check the central junction box for related DTCs and refer to the relevant DTC index
• Refer to the electrical circuit diagrams and check the trailer fog lamp circuit for high resistance. Repair the wiring harness as necessary

SYMPTOM:

Trailer fog lamp(s) stuck on

POSSIBLE CAUSE:

• Body system fault
• Trailer fog lamp circuit short circuit to power

ACTION:

• Using the Jaguar Land Rover approved diagnostic equipment, check the central junction box for related DTCs and refer to the relevant DTC index
• Refer to the electrical circuit diagrams and check the trailer fog lamp circuit for short circuit to power. Repair the wiring harness as necessary

SYMPTOM:

Trailer tail / license plate lamp(s) inoperative

POSSIBLE CAUSE:

• Body system fault
• Trailer tail / license plate lamp circuit short circuit to ground, short circuit to power, open circuit, high resistance

ACTION:

• Using the Jaguar Land Rover approved diagnostic equipment, check the central junction box for related DTCs and refer to the relevant DTC index
• Refer to the electrical circuit diagrams and check the trailer tail / license plate lamp circuit for short circuit to ground, short circuit to power, open circuit, high resistance.

  Repair the wiring harness as necessary

SYMPTOM:

Trailer tail / license plate lamp(s) dim

POSSIBLE CAUSE:

• Body system fault
• Trailer tail / license plate lamp circuit high resistance

ACTION:

• Using the Jaguar Land Rover approved diagnostic equipment, check the central junction box for related DTCs and refer to the relevant DTC index
• Refer to the electrical circuit diagrams and check the trailer tail / license plate lamp circuit for high resistance. Repair the wiring harness as necessary

SYMPTOM:

Trailer tail / license plate lamp(s) stuck on

POSSIBLE CAUSE:

• Body system fault
• Trailer tail / license plate lamp circuit short circuit to power

ACTION:

• Using the Jaguar Land Rover approved diagnostic equipment, check the central junction box for related DTCs and refer to the relevant DTC index
• Refer to the electrical circuit diagrams and check the trailer tail / license plate lamp circuit for short circuit to power. Repair the wiring harness as necessary

SYMPTOM:

Trailer turn signal indicator lamp(s) inoperative

POSSIBLE CAUSE:

• Body system fault
• Trailer turn signal indicator lamp circuit short circuit to ground, short circuit to power, open circuit, high resistance

ACTION:

• Using the Jaguar Land Rover approved diagnostic equipment, check the central junction box for related DTCs and refer to the relevant DTC index
• Refer to the electrical circuit diagrams and check the trailer turn signal indicator lamp circuit for short circuit to ground, short circuit to power, open circuit, high resistance.

  Repair the wiring harness as necessary

SYMPTOM:

Trailer turn signal indicator lamp(s) dim

POSSIBLE CAUSE:

• Body system fault
• Trailer turn signal indicator lamp circuit high resistance

ACTION:

• Using the Jaguar Land Rover approved diagnostic equipment, check the central junction box for related DTCs and refer to the relevant DTC index
• Refer to the electrical circuit diagrams and check the trailer turn signal indicator lamp circuit for high resistance. Repair the wiring harness as necessary

SYMPTOM:

Trailer turn signal indicator lamps stuck on

POSSIBLE CAUSE:

• Body system fault
• Trailer turn signal indicator lamp circuit short circuit to power

ACTION:

• Using the Jaguar Land Rover approved diagnostic equipment, check the central junction box for related DTCs and refer to the relevant DTC index
• Refer to the electrical circuit diagrams and check the trailer turn signal indicator lamp circuit for short circuit to power. Repair the wiring harness as necessary

SYMPTOM:

Trailer reverse lamp(s) inoperative

POSSIBLE CAUSE:

• Body system fault
• Trailer reverse lamp circuit short circuit to ground, short circuit to power, open circuit, high resistance

ACTION:

• Using the Jaguar Land Rover approved diagnostic equipment, check the central junction box for related DTCs and refer to the relevant DTC index
• Refer to the electrical circuit diagrams and check the trailer reverse lamp circuit for short circuit to ground, short circuit to power, open circuit, high resistance. Repair the wiring harness as necessary

SYMPTOM:

Trailer reverse lamp(s) dim

POSSIBLE CAUSE:

• Body system fault
• Trailer reverse lamp circuit high resistance

ACTION:

• Using the Jaguar Land Rover approved diagnostic equipment, check the central junction box for related DTCs and refer to the relevant DTC index
• Refer to the electrical circuit diagrams and check the trailer reverse lamp circuit for high resistance. Repair the wiring harness as necessary

SYMPTOM:

Trailer reverse lamp(s) stuck on

POSSIBLE CAUSE:

• Body system fault
• Trailer reverse lamp circuit short circuit to power

ACTION:

• Using the Jaguar Land Rover approved diagnostic equipment, check the central junction box for related DTCs and refer to the relevant DTC index
• Refer to the electrical circuit diagrams and check the trailer reverse lamp circuit for short circuit to power. Repair the wiring harness as necessary

SYMPTOM:

Warning indicator(s) inoperative

POSSIBLE CAUSE:

• Body system fault
• Instrument cluster fault

ACTION:

• Using the Jaguar Land Rover approved diagnostic equipment, check the central junction box for related DTCs and refer to the relevant DTC index
• Using the Jaguar Land Rover approved diagnostic equipment, check the instrument cluster for related DTCs and refer to the relevant DTC index

SYMPTOM:

Trailer connector power (battery) circuit inoperative

POSSIBLE CAUSE:

• Trailer connector power (battery) circuit short circuit to ground, open circuit, high resistance

ACTION:

• Refer to the electrical circuit diagrams and check the trailer connector power (battery) circuit for short circuit to ground, open circuit, high resistance. Repair the wiring harness as necessary

SYMPTOM:

Trailer connector power (ignition) circuit inoperative

POSSIBLE CAUSE:

• Trailer connector power (ignition) circuit short circuit to ground, open circuit, high resistance

ACTION:

• Refer to the electrical circuit diagrams and check the trailer connector power (ignition) circuit for short circuit to ground, open circuit, high resistance. Repair the wiring harness as necessary

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 Index - DTC: Central Junction Box (CJB) (100-00 General Information, Description and Operation).

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