I Dont know if its faulty compressor, i dont have any test gear.The symtoms are when the air tank is full if you press the brake pedal 4 or 5 times whilst the lorry is ticking over the air decreases rapidly and the stop light comes on. The lorry is about 10 years old, the only thing i noticed is that i didnt hear the air pressure valve blow off when the tank is full

kev, November 2008

Just to update everyone i found the fault, it was a bad earth showing little air in tanks on gauge. Found more faulty gauges as time went on, eventually the whole dash then lit up like a christmas tree at times so checked the earths and luckily enough that solved it

kev, December 2008

Hi berty b thanks for reply. i have tried the tanks and they are fine but i havent tried the air drier filter canister didnt realize there was one on it, what does it look like

kev, November 2008

are your air tanks full of water or sludge ?.this can reduce air tank capacity greatly. have you changed the air drier filter canister yearly.

berty b, November 2008

Hi thanks for reply forgot to mention that there,s no air leaks

kev, November 2008

check flexible pipe from comp outlet to chassis for leaks

k, November 2008