JD1435 series 1 glow plug wiring diagram and component locations

[TheEquineFencer]

I'm trying to help a good friend out. He has a JD1435 I think it's what he calls a series 1. The GPs do not work, no power to them. He's been throwing parts at it. New timer, I think that's what it is. Right side of mower beside three relays. If You unplug it, the GP light on the dash will not work. The wires to it are to small to carry enough current for the GPs, so I'm guessing there a power relay that it controls somewhere. I did notice there's an open relay base under the seat hanging loose, but nothing has been plugged in it for a while.

A wiring diagram would be helpful as we (ME) does not want to cut the woven harness apart to trace out the circuit.

 

[Roadworthy]

I know absolutely nothing about a JD 1435 or any other John Deere. I do not know the age of the unit so consider any information general. Generally glow plugs are wired in parallel. If you have power to one you'll have power to all. Glow plugs generally need 10.5 volts, not 12. Older tractors use a nichrome resistance wire in series with them to drop the voltage. They are wound in a coil and glow to indicate they have power, though frequently the glow cannot be seen - it's not bright. Over time the contacts corrode and current can no longer pass. Newer units may have a controller which may limit the current. You may need to find a manual for your particular model. You can measure the resistance of the glow plugs from the tip of each to ground. Since they're in parallel each one must be disconnected to accurately measure it. They should be a VERY low resistance from tip to ground - not a short but only perhaps half an ohm.