Definately the brake switches and clutch switches have to wired in
especially the brake switch had a ba/bf cant remember which one the other day exact same thing fang it in 1st goes well,
get it into second and then only 3 psi boost,
checked all the fault codes and found brake switch, installed a new one cleared fault codes straight up to 6-7 psi
any ways the guy that posted this never came back with the answer or the fix to his vehicle, we would love to hear if you got it fixed???