hi guys n gals

posted up a few days ago about my rev counter giving out half readngs, some decent fella sent me a piccy, so i got the diodes

they were 1N4004

i wired em in to the car today and it just seemed to short out the car

had to go back to hoe it was

are these diodes 'on way current' jobbies? is there a correct way round to have them? there is a white band on the end of the diode, which end should i connect this to? coming from the coil,,or the other end?

help would really be appreciated guys, i got stuck in soton for 45 mins cos of this lmao, though it would be a 5 min job!