Hi guy's , how do you get around having to use the "volvo test diode" to ck. for ignition ecu code's; can you use a voltmter instead ,or make your own; I,m having a prob. w/serious spark knock[reduced timing to avoid damage], all of a sudden,i think it's either the k/sensor or system wiring/ecu connection's or failure. I have a Lab o/scope i borrowed from work to watch the knock signature wave tommorrow[sun.] , but i would like some input+ opinion's on this prob. e-m me w/ any suggestion's tommorow, thanx, g.b.