I have a 2013 prius with the brake light coming on and off, sometimes stays on, if you disconnect the brake light switch, the light still stays on. We put a new battery in - 12v - but the issue remains. Can anyone advise me what the issue may be on this issue, and also if anyone else has had this issue? Thank you very much.
The wiring diagram is quite simple. Check if all brake lights are constantly on? Stop by MAX2 posted Sep 5, 2024 at 12:32 PM
Indeed, deceptively so. Toyota has this way of splitting the Electrical Wiring Diagram into sections, with each section showing only the portion of something that pertains to that section. The diagram above makes the "stop light control ECU assembly" look like it only has four connections (at pins 1, 5, 6, and 8, which might make you suspicious you're not being shown everything). There are other sections in the full Electrical Wiring Diagram that show other connections to the same unit. For example, it has an ACC input (yellow, pin 9) the skid control ECU can use to flash the brake lights even when you're not pressing the pedal) and also an ESSI or ESS1 connection (beige, pin 4). Elektroingenieur offered some more information on those in this post.
Valuable remark. Indeed, in Toyota electrical diagrams I have encountered situations where only part of the wiring that goes to the electronic unit was shown. The other part of the wiring was in other sections.
