JoJoMac
Guest
kpr, The fact that you had less voltage with the switch on than off is normal. There's a big current load in that circuit and the batteries won't supply when the engine isn't running, or more to the point the alternator isn't supplying current. But you should have had more than 3VDC, and your lights still oughta light with the engine off. So...lemme give you a couple things to check. First verify your battery condition. Yep, they can, sometimes, start the engine with less than 12VDC. Check voltage at the batteries, between each post and the ground point on the engine frame. The positive cable is notorious for corrosion inside the insulation. Next verify your alternator output. You should be within a half volt of 14. If it's the same as the batteries you just checked there's the problem. If you're okay there look at the engine compartment relay panel. On that panel there is a fifty amp circuit breaker that is also prone to failure. There are different configurations of that panel for different serial numbers, your owners manual will tell you which one you want.While you're bent over looking at that, check the voltage at the relay that powers the power distribution board. Once again your owners manual will identify the proper one. Next check the power distribution board for the proper relays and breakers in the lighting circuit. If your combine is a late enough model it will have fuses. (Not a likely culprit in your scenario.) Remember, a cicuit breaker may test alright for continuity but still be unable to carry a load. While you're in the main electronics box, take a couple of minutes to blow the dust out of it. That will prolong the life of those printed circuits. There are many other places to look, but I think you'll find the problem in one of these areas, most likely the engine compartment. And be careful. Joe