Brake lights via bus message (substitute function)
This function replaces the lead between the brake light switch (29) and REC (701) in the event of a break along the lead. The function is only active when the ignition switch is in the ON or START position.
Depressing the brake pedal will affect the brake light switch (29). The brake light switch (29) is supplied with +30 on pin 1, when the switch closes B+ will be applied to pin 2. From the brake light switch pin 2, voltage is supplied to the engine control module and to REC (701) pin 5 (B2-D). When the brake light switch (29) is activated, voltage is fed to an input on the ECM. The engine management system uses this input for its own functions, e.g. cruise control, but also sends the input status on the bus as a bus message "Brake pedal switch, active" ON. This bus message is used by REC only when the ignition is in ON or START position as a substitute for the input on REC. REC feeds B+ (PWM 100%) from pin 2 (R-D) to the light cluster (30/418RL) pin 2 for the left-hand brake light and from pin 4 (R-D) to the light cluster (30/418RR) pin 2 for the right-hand brake light plus from pin 15 (H-2) to the high level brake light (30RC) pin 2. The light cluster (418RL/RR) pin 3 is grounded to grounding point G3 (left) and G29 (right) respectively. The high level brake light (30RC) pin 3 is grounded to grounding point G3.