:  Dec 17, 2007



Overview

For information on the description and operation of the system, refer to section 417-01 - Exterior Lighting of the workshop manual.

Prior to carrying out fault diagnosis of the trailer lamp system, verify the operation of the towing vehicle lighting system with the trailer lighting plug(s) disconnected from the vehicle socket(s).

Note that intermittent fault reports may be due to the cycling operation of the field effect transistors (FETs).

Inspection and Verification

. Verify the customer concern.

. Visually inspect for obvious electrical faults.

Mechanical Electrical
  • Trailer lamp(s) condition and installation
  • Bulbs and installation
  • Bulb holders and installation
  • Trailer socket(s), plug(s) and installation
  • Fuses Battery junction box (BJB) - link 18E BJB - link 11E Central junction box (CJB) - Fuse 22P (CJB) - Fuse 8P (CJB) - Fuse 6P (CJB) - Fuse 32P (CJB) - Fuse 14P Trailer fuse box - Fuse to trailer socket relay Trailer fuse box - Fuse to trailer socket battery feed Trailer fuse box - Fuse to trailer socket brake lamp Trailer fuse box - Fuse to trailer socket fog lamps Trailer fuse box - Fuse to trailer socket right hand tail lamp Trailer fuse box - Fuse to trailer socket number plate and left hand tail lamps
  • Relays Reverse lamp relay Side lamp relay trailer socket relay
  • Stop lamp switch
  • Wiring harness
  • Loose or corroded connector(s)
  • Trailer socket(s) ground circuit(s)
  • Battery junction box (BJB)
  • Central junction box (CJB)
  • Trailer fuse box
  • Trailer relay box
  • Instrument panel cluster (IPC)
  • Controller area network (CAN) circuits

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

. Use the approved diagnostic system or a scan tool to retrieve any diagnostic trouble codes (DTCs) before moving onto the symptom chart or DTC index.
  Because the DTCs are stored in more than one module, a complete vehicle read is recommended.
Because the DTCs are stored in more than one module, a complete vehicle read is recommended.
  Make sure that all DTCs are cleared following rectification
Make sure that all DTCs are cleared following rectification

Symptom Chart

Symptom Possible causes Action
Trailer brake lamp(s) inoperative
  • Bulb failure
  • Fuse(s) blown
  • Circuit fault
  • Brake lamp switch fault
Check the bulb and fuse condition (see visual inspection). Check the trailer brake lamp circuit. Check the brake lamp switch function. Refer to the electrical guides.
Trailer brake lamp(s) dim
  • Incorrect bulb rating
  • Circuit fault
  • Brake lamp switch fault
Check the bulb condition and rating. Check the trailer brake lamp circuit. Check the brake lamp switch function. Refer to the electrical guides.
Trailer brake lamp(s) stuck on
  • Circuit fault
  • Brake lamp switch fault
Check the trailer brake lamp circuits. Check the brake lamp switch function. Refer to the electrical guides.
Trailer fog lamp(s) inoperative
  • Bulb failure
  • Fuse(s) blown
  • Circuit fault
Check the bulb and fuse condition (see visual inspection). Check the trailer fog lamp circuit. Refer to the electrical guides.
Trailer fog lamp(s) dim
  • Incorrect bulb rating
  • Circuit fault
Check the bulb condition and rating. Check the trailer fog lamp circuit. Refer to the electrical guides.
Trailer fog lamp(s) stuck on
  • Circuit fault
Check the trailer fog lamp circuit. Refer to the electrical guides.
Trailer tail and number plate lamp(s) inoperative
  • Bulb failure
  • Fuse(s) blown
  • Circuit fault
  • Trailer side lamp relay fault
Check the bulb and fuse condition (see visual inspection). Check the trailer tail and number plate lamp circuit. Check the trailer tail and number plate lamp relay function. Refer to the electrical guides.
Trailer tail and number plate lamp(s) dim
  • Incorrect bulb rating
  • Circuit fault
  • Trailer side lamp relay fault
Check the bulb condition and rating. Check the trailer tail and number plate lamp circuit. Check the trailer side lamp relay function. Refer to the electrical guides.
Trailer tail and number plate lamp(s) stuck on
  • Circuit fault
  • Trailer tail and number plate lamp relay fault
Check the trailer tail and number plate lamp circuit. Check the trailer tail and number plate lamp relay function. Refer to the electrical guides.
Trailer turn signal lamp(s) inoperative
  • Bulb failure
  • Fuse(s) blown
  • Circuit fault
Check the bulb and fuse condition (see visual inspection). Check the trailer turn signal lamp circuit. Refer to the electrical guides.
Trailer turn signal lamp(s) dim
  • Incorrect bulb rating
  • Circuit fault
Check the bulb condition and rating. Check the trailer turn signal lamp circuits. Refer to the electrical guides.
Trailer turn signal lamp(s) stuck on
  • Circuit fault
Check the bulb and fuse condition (see visual inspection). Check the trailer turn signal lamp circuit. Refer to the electrical guides.
Trailer reverse lamp(s) inoperative
  • Bulb failure
  • Fuse(s) blown
  • Circuit fault
  • Trailer reverse lamp relay fault
Check the bulb and fuse condition (see visual inspection). Check the trailer reverse lamp circuit. Check the trailer reverse lamp relay function. Refer to the electrical guides.
Trailer reverse lamp(s) dim
  • Circuit fault
  • Trailer reverse lamp relay fault
Check the bulb condition and rating. Check the trailer reverse lamp circuit. Check the trailer reverse lamp relay function. Refer to the electrical guides.
Trailer reverse lamp(s) stuck on
  • Circuit fault
  • Trailer reverse lamp relay fault
Check the trailer reverse lamp circuit. Check the trailer reverse lamp relay function. Refer to the electrical guides.
Warning lamp(s) inoperative
  • Fuse(s) blown
  • Circuit fault
  • Instrument cluster fault
Check the fuse(s) (see visual inspection). Check the warning lamp circuit. Refer to the electrical guides. Check for DTCs indicating an instrument cluster or CAN system fault.
Trailer socket battery feed missing
  • Fuse(s) blown
  • Circuit fault
Check the fuse condition (see visual inspection). Check the trailer battery feed circuit. Refer to the electrical guides.
Trailer socket ignition feed missing
  • Fuse(s) blown
  • Circuit fault
  • Trailer socket relay faulty
Check the fuse condition (see visual inspection). Check the trailer ignition feed circuit. Check the trailer ignition feed relay operation. Refer to the electrical guides.

DTC index

:
  Generic scan tools may not read the codes listed, or may read only 5-digit codes. Match the 5 digits from the scan tool to the first 5 digits of the 7-digit code listed to identify the fault (the last 2 digits give extra information read by the manufacturer-approved diagnostic system).

DTC Description Possible causes Action
B1D0811 Lefthand Trailer Direction Indicator Circuit
  • Left trailer turn signal short circuit to ground
Refer to the guided diagnostic routine for this code on the approved diagnostic system.
B1D0815 Lefthand Trailer Direction Indicator Circuit
  • Left trailer turn signal short circuit to power
  • Left trailer turn signal: high resistance
Refer to the guided diagnostic routine for this code on the approved diagnostic system.
B1D0911 Righthand Trailer Direction Indicator Circuit
  • Right trailer turn signal short circuit to ground
Refer to the guided diagnostic routine for this code on the approved diagnostic system.
B1D0915 Righthand Trailer Direction Indicator Circuit
  • Right trailer turn signal short circuit to power
  • Right trailer turn signal high resistance
Refer to the guided diagnostic routine for this code on the approved diagnostic system.
U1A1449 CAN Initialization Failure
  • Internal electronic failure
Check the power and ground circuits to the component. Refer to the electrical guides. Configure the module(s) using the approved diagnostic system. Refer to the warranty policy and procedures manual if a module is suspect.