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Last weekend it was below freezing for a couple of days. The tractor almost started after a 20 second glow plug cycle. A second cycle and it fired right up. My diesel truck wouldn’t start after a 10 hour plug in of the heater block. Temps will be single digits tomorrow, so I am curious as to what it will do.
I ran a 10 awg in addition to the original glow plug wire. The voltage stayed about 11.2v with plugs engaged. I welded the bolt to the frame for the battery ground connection—no change in voltage. I put jump box on battery—no change in voltage. Maybe a brand new battery might get the voltage at the plugs to 12v.
Sort of, I pulled the hot wire from the starter and triggered the relay from the key switch. But, I only used #12 wire for +12v. I may have to resize both wires.
I put in a glow plug relay, but did not change the wire to the plugs. I ran a fused 12 awg to the relay. That is an easy fix.
I went ahead and put the glow plug in the tractor. I marked the position of the tractor amp meter before replacement. The current draw went down with the new one installed which indicates it now has a slightly higher overall resistance. Since the plugs are parallel, they have to have lower total resistance than any individual one. If the newest one is 1.2 ohms and at 12 volts means a 10 amp draw. It could go up to 18 amps if the other two were 0.3 ohms. I did find it curious that the voltage at the cross bar drops to 10.7 volts when the plugs are engaged. Maybe a ground problem or weak battery?
I probably didn’t state that right. I rigged it up and before I attached the + lead to the glow plug, the readout was 0v/50a. The display was powered by the same 12v that’s supplied to the plug. When I triggered the glow plug I hoped the readout would change, but it stayed at 0v/50a. The yellow and black wires were measuring the voltage across the shunt and the red wire was attached to the +12v supply. I found the schematic online and it may not be for this display, but the wiring scheme appeared to be the same.
First, the new glow plug is 1.2 ohms and my Fluke has been pretty reliable. As for the amp meter, Argh! I wired it up exactly like the diagram and it showed 0 volts and 50 amps without powering the new glow plug and the same when the glow plug glowed. Back to the drawing board…
You would think it would read the voltage just like a multimeter, but it also says it’s range can be used on 4.5 to 30 Volts DC. It reads a voltage across the shunt and converts that to the corresponding current through the shunt. So, maybe it needs to know the source voltage for the calculation? It’s already more complicated than I was expecting. It’s going to be rainy tomorrow so I should have time to test it.
I am going to try and wire it up using 2 jump boxes first, just to see if I can get it to work. The diagrams show a voltage adjust so I hope I don’t have to do any tweaking.
