hi. my car is proton waja campro with ecu700 siemens. I have been trying to solve this cel forever. Dtc is P0703 which means brake light switch not plausible. I have check with scanner and used the live data function to check if it is registering the brake pedal and it does but i checked it through the abs module as the ecu do not offer such live data. Ive checked the outputs from the brake switch and there is 4 wires where 2 wires will open circuit and 2 wire will close circuit when pressing and depressing the switch and it checks out. I have changed the brake switch not once but twice. the weird thing is the check engine light did go out randomly before but after a few weeks returned back with the same code, not light bulb loose as cel did light up during first few seconds of starting. i have adjusted the brake switch properly many times. NON of the light bulbs are blown and even changed them all out.

so please electrical geniuses help me out as this has been going on after mco where the car sat for 2-3 years and i do not know the condition it was before that.

mods: non (very stock)

i have been thinking if there are any ecu workshops or ecu tuning workshops where they can hide this code so that the cel will still light if got problem but will not light when got this code.

pls give suggestions thank you

I suppose you cleaned the connector to the brake switch

During the fault did the brake light turn on off?

Checked all fuses and relay?

https://www.youtube.com/watch?v=xsZ965K-hu0
he reset once bulb are replaced. have u did reset clear code?

Are you using LED brake lights all round? I mean both left and right P21W/5W and 3rd brake light 1156 (I think) are all LED?

During the fault did the brake light turn on off?

[/quote]when pressing brake it turns on and releasing turn off.


yup everything is good.


i have tried resetting using obd2 and removing battery terminal for the whole day.


no led except license plate lights which are just t10.