Diagnostics and testing of interior lighting (Discovery 3)

Inspection and verification

1. Ensure that the customer's complaint is justified.

2. Visually inspect for obvious electrical problems.

Mechanical factors

Electrical factors

Main interior light - condition and correct installation Condition and installation of reading lamp(s) Condition and installation of the lamp(s) for illumination of cosmetic mirrors Glove Compartment Light Status and Installation Condition and installation of footwell lighting lamp(s) Ignition Switch Bezel Lighting Condition and Installation Condition and installation of additional side lights Condition and installation of the backlight lamp(s) in one Condition and installation of luggage compartment light

Lamps Fuses Battery Junction Box (BJB) - 15E fuse link BJB - 11E fuse link Central Junction Box (CJB) - 1P fuse BJB CJB Battery charge retention relay Wiring harness Loosening or corrosion of connector(s) Main interior light switch Reading Light Switches Vanity Mirror Light Switches Glove Compartment Lamp Switch LED Flowing Light Tailgate Light Switch

3. If an obvious cause for the problem you identified or the customer described is found, resolve it before moving on to further action. (if possible).

4. Use the approved diagnostic system or scan tool to retrieve all diagnostic trouble codes (DTCs) before referring to the symptom chart or DTC index.

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Clear all DTCs after troubleshooting.

Table of signs of malfunction

Sign of malfunction	Possible reasons	Actions
The main interior light does not work	The lamp(s) is faulty The fuse(s) have blown Electrical circuit failure Switch malfunction	Check the condition of the lamp(s). Check the fuse(s). (see visual inspection). Check the electrical circuits of the lamps. Check the operation of the switch. Refer to the electrical equipment manual.
The LED flowing light does not work	The LED is faulty The fuse(s) have blown Electrical circuit failure	Check LED status. Check LED connector. Check fuse(s) (see visual inspection). Check the electrical circuits of the lamps. Refer to the electrical equipment manual.
Reading lamp(s) not working	The lamp(s) is faulty The fuse(s) have blown Electrical circuit failure Switch malfunction	Check the condition of the lamp(s). Check the fuse(s). (see visual inspection). Check the electrical circuits of the lamps. Check the operation of the switch. Refer to the electrical equipment manual.
The light(s) for the vanity mirrors do not work	Lamp failure The fuse(s) have blown Electrical circuit failure Switch malfunction	Check the lamp condition. Check the fuse(s) (see visual inspection). Check the electrical circuits of the lamps. Check the operation of the switch. Refer to the electrical equipment manual.
The glove compartment light does not work	Lamp failure The fuse(s) have blown Electrical circuit failure Switch malfunction	Check the lamp condition. Check the fuse(s) (see visual inspection). Check the electrical circuits of the lamps. Check the operation of the switch. Refer to the electrical equipment manual.
Footwell light(s) not working	Lamp failure The fuse(s) have blown Electrical circuit failure	Check the lamp condition. Check the fuse(s) (see visual inspection). Check the electrical circuits of the lamps. Refer to the electrical equipment manual.
Ignition switch bezel illumination does not work	Lamp/bezel faulty The fuse(s) have blown Electrical circuit failure	Check the condition of the lamp/bezel. Check the fuse(s) (see visual inspection). Check the electrical circuits of the lamps. Refer to the electrical equipment manual.
The side light(s) built into the outside mirror does not work	Lamp failure The fuse(s) have blown Electrical circuit failure	Check the lamp condition. Check the fuse(s) (see visual inspection). Check the electrical circuits of the lamps. Refer to the electrical equipment manual.
The entrance light(s) do not work	Lamp failure The fuse(s) have blown Electrical circuit failure	Check the lamp condition. Check the fuse(s) (see visual inspection). Check the electrical circuits of the lamps. Refer to the electrical equipment manual.
The luggage compartment light does not work	Lamp failure The fuse(s) have blown Electrical circuit failure Switch malfunction	Check the lamp condition. Check the fuse(s) (see visual inspection). Check the electrical circuits of the lamps. Check the operation of the switch. Refer to the electrical equipment manual.

DTC Index

NOTE: Generic scan tools cannot read the codes listed or can only read 5-digit codes. Match the 5 digits from the scan tool with the first 5 digits of the listed 7-digit code to identify the fault. (the last 2 digits provide additional information readable by a manufacturer approved diagnostic system).

DTC codes	Description	Possible reasons	Actions
B1C4323	Main interior light switch	Signal stuck Switch pressed Interior Light Circuit Short to Ground The interior light switch is faulty	Refer to the guided diagnostic routine for this code on the approved diagnostic system. Refer to the electrical manual and check the interior lamp circuit. Check the switch operation and replace if necessary.
B1C9511	Electrical circuit of additional side lights	Additional side light electrical circuit: short circuit to ground	Refer to the guided diagnostic program for this code on the approved diagnostic system. Refer to the electrical guides and check the auxiliary parking lamp circuit. (if available). Replace/repair if necessary. If no such device is present, check the vehicle configuration. Clear/ignore DTC.
B1C9515	Electrical circuit of additional side lights	Additional side light electrical circuit: short circuit to battery +	Refer to the guided diagnostic program for this code on the approved diagnostic system. Refer to the electrical guides and check the auxiliary parking lamp circuit. (if available). Replace/repair if necessary. If no such device is present, check the vehicle configuration. Clear/ignore DTC.
B1D1311	Interior Lighting Circuit "A"	Interior Light Circuit A: Short to Ground	Refer to the guided diagnostic program for this code on the approved diagnostic system. Refer to the electrical guides and check the circuit. Repair as necessary.
B1D1315	Interior Lighting Circuit "A"	Interior Light Circuit A: Short to Battery +	Refer to the guided diagnostic routine for this code on the approved diagnostic system. If there is no customer complaint regarding interior light operation, no action is required, clear/ignore the DTC. If interior light operation is not normal, refer to the electrical guides and check the circuit. Repair as necessary.
B1D1411	Interior lighting electrical circuit "B"	Interior Light Circuit B: Short to Ground	Refer to the guided diagnostic program for this code on the approved diagnostic system. Refer to the electrical guides and check the circuit. Repair as necessary.
B1D1415	Interior lighting electrical circuit "B"	Footwell/entry lights not installed Lamp failure The fuse(s) have blown Electrical circuit failure	Check the installation of the footwell/entry lights. If the lights are NOT installed, ignore this DTC. If the lights are installed, refer to the guided diagnostic routine for this code on the approved diagnostic system. Check the condition of the bulbs/fuses. Refer to the electrical diagrams and check the lamp circuits for shorts, open circuits.