AM says if you replace the brake booster assembly you need to install new brake light stot switch which turn s on brake light when you apply the brake.

I had hissing high pitched noise in cold weather when I apply brake and release it for a while initially it was intermittent but then because more frequent over 2-3 years so finally decided to replace brake booster assembly. Found on eBay from 2016 db9 salvage part came with booster, master cylinder and brake fluid reservoir ( which mine had innumerable fine cracks)

swapping out booster is not tgat difficult but you do have to move coolant reservoir (held by 2 bolts) , disconnect 2 tubes on right of reservoir and one on left side then remove 2 bolts which holds large Reiner tube from bottom of reservoir going to front of car on side wall that will give you flexibility to just flip the reservoir bump about 90 degree , you also have to loose oil dip stick not have to remove completely but loosen it so it can be moved out of the way to creat space for booster to come out

you have to disconnect two brake liners with 11 mm ratchet from master cylinder, remove 2 bolts

you know I will just post a video on this



back to reusing the switch see this video

 

Good for you figuring out how to reset the switch, but for future reference, that is a bog standard Ford switch used on millions of Fords, Mazdas, and yes, Aston Martins! And as a result widely available in all parts stores and with tons of aftermarket copies. I had an issue with mine not activating the brake lights properly and replaced it with a Dorman 926-487 for all of $15 or so and it works perfectly.

 

yes that’s correct now s days with google photo search it’s easy to find parts from other manufacturing provider but it’s fun to fix things. I enjoy fixing