Hi All,can anyone help with my brake problem????????

I have just bought a 95 model 300tdi classic which has developed a brake problem. The pump was running all the time ,I drove it abouit 1/2 mile when the brakes started to grab occasionally,1/4 mile later the brakes locked on. Luckily i stopped right outside a garage who cracked the bleed nipples and released the pressure enough to drive back where I came from. I can seem to find any info as to what the cause maybe. Suggestions gratefully received!!!!!!!!!!!.

I could be wrong but it sounds like the pressure switch is faulty. keeps the pump running. Either that or a major short in the wiring.

Thanks for the info I will link out the switch to see if it makes any difference