ok,please bear in mind that this comes from a mechanical incompetent but when i turn ignition on there is a repeated loud clunking noise coming from what i think is the glow plug relay, the voltmeter gos from about 10v to 13v at the same time.Truck starts ok but is it time for a new relay? One other thing,got a cd manual thru the site but have just found out that i can't access the electrics chapter sign comes up saying file corrupted any way to exchange/replace disc?(not only mechanical incompetent but computer illiterate as well)