Diagnostics and testing of brake lights (Discovery 3)

Review

For a detailed description of the system design and operation, refer to Section 417-01 "Steering System" in the Workshop Manual. Note that the brake lights come on automatically under certain conditions when using the vehicle handling optimization function, refer to Section 204-06 "Vehicle Handling Optimization" in the Workshop Manual.

Inspection and verification

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

2. Visually inspect for obvious electrical problems.

Mechanical factors	Electrical factors
Condition and installation of brake lights Lamps and installation Lamp holders and installation Brake light switch condition and installation	Fuses Battery electrical junction box (BJB) - fuse 16E BJB - fuse 11E Central electrical junction box (CJB) - fuse 15P CJB - fuse 66P Wiring harness Loosening or corrosion of connector(s) Controlled descent system relay Battery Junction Box (BJB) Central Junction Box (CJB) ABS control module CAN electrical circuits (Control Area Network)

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.

Since DTCs are stored in more than one module, a full vehicle data read is recommended.

The material was taken from the specified website [LRman.ru]



Clear all DTCs after troubleshooting.

Table of signs of malfunction

Sign of malfunction	Possible reasons	Actions
Brake light(s) not working	Lamp failure LED malfunction The fuse(s) have blown Electrical circuit failure Brake light switch malfunction	Check the condition of the lamp, LED and fuse (see visual inspection table). Check the brake light circuits. Check the brake light switch for proper operation. Refer to the electrical manual. Check for DTCs indicating a brake light circuit malfunction.
Dim brake light(s)	Incorrect lamp power Electrical circuit failure	Check the condition and power of the lamp. Check the electrical circuits of the brake lights. Refer to the electrical equipment manual.
Brake light(s) are constantly on	Brake light switch malfunction Electrical circuit failure Controlled descent system relay electrical circuit malfunction	Check the operation of the brake light switch. Check the brake light circuits. Refer to the electrical manual. Check for DTCs indicating a malfunction in the brake light circuit.

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
C110501	Brake light control	General electrical fault Brake light control: short circuit to battery + Brake light control: short circuit to ground	Check the brake light control circuits. Refer to the electrical manual.
C110567	Brake light control	Incorrect signal after event	Check the brake light circuits. Refer to the electrical manual.
C1A9613	Brake light switch	Brake light switch electrical circuit: short circuit to battery +	Check the brake light switch and electrical circuits. Refer to the electrical manual.
C1A9624	Brake light switch	Brake Light Switch Circuit: Signal Stuck at High Voltage	Check the brake light switch and electrical circuits. Refer to the electrical manual.
C1A9662	Brake light switch	Signal comparison failure	Check the brake light switch and electrical circuits. Refer to the electrical manual.
C1A9664	Brake light switch	Lack of signal credibility	Check the brake light switch and electrical circuits. Refer to the electrical manual.
U1A1449	CAN initialization failure	Internal electronic malfunction	Check the electrical power and ground circuits of the unit. Refer to the electrical manual. Configure the module(s) using the approved diagnostic system. If a module is suspect, refer to the warranty policy and procedures manual.