2006 grand vitara brake lights comes on when accelerating from stop

Question edited for clarity, add maker.
Question moved to make model category.

Check the fuses and relays.

Fuse Box Diagram Suzuki Grand Vitara (JT; 2005-2015)

https://fuse-box.info > suzuki > suzuki-grand-vitara-jt-2...

In this article, you will find fuse box diagrams of Suzuki Grand Vitara 2005, 2006, 2007, 2008, 2009, 2010, 2011, 2012, 2013, 2014 and 2015, get information ...

Correct. When you turn off the engine you lose the engine vacuum to the brake boost assist. No brakes. Can't accelerate with engine off.

http://www.fixya.com/cars/t26262849-07_grand_vitara_4x4_4x4_lights_come https://www.carbuyer.co.uk/reviews/suzuki/grand-vitara/sports-utility-vehicle/owner-reviews

Put seafoam for cleaning system go to auto zone they will tell you.

this is a complex car, and engines.
Just 1 code? and no pendings?
A DIESEL engine , and in USA , are ya> or in Canada?

the shop manual for all complex cars, is a must have.

P2 codes are factory codes, unique to only Suzuki ,
so use their books.
alldata dot com has it.

"Particulate Trap Efficiency Below Threshold Malfunction "
but cleaning it , is not the only way to fix it.
the manual covers this, and how the test works and what can make it fail, simple swaps or cleans dont always work.
RTM please.

what about bulbs

probably need to add a little brake fluid to the reservoir--it's in the engine compartment just in front of you. Brake fluid level decreases normally as front brakes wear. If it uses too much, check all wheels for a leak.

Some suggestions - performance air filter (free flow type), dual exhaust, low back pressure muffler(s), platinum spark plugs, better plug wires, synthetic oils and fluids.

If there is ABS on the car it is the ABS detecting the difference inthe wheel RPM that is triggering off the brake light.
so not to worry as this happens and specially if your brake fluids are full.
The other reason is the momentum is setting off the brake fluid sensor to switch on .

Obviously, in different markets, there will be different wiring set-ups. In Australia, both the brake lights and horn work when the ignition is off and they share a fuse. If your horn doesn't work, maybe your brake lights don't either.