Leave the sensors alone, For that matter leave the relays alone. Leave everything as it is. Now install your own 70 amp relay, whose one side of the coil goes to the ignition +12 volt buss, the other side of the coil goes to a momentary push button that goes to ground, With the ignition key on, press and hold the button for 15 seconds, release it, start engine, and post glow by pressing the button for about 10 seconds after the engine runs. release button. Obviously the contacts of the relay go to the battery and the glow plug buss. It doesn't get any simpler than this. Obviously remove and store the original leads going to the glow plug buss. You don't care what the ECU is doing, what the sensors are doing or even what the original relays are doing.
Yupp...
When I was working at the car dealer workshop, we had a man who could repair the ECUs or injection computers of old cars at low cost.
Even if Kubota does the work? Ouch. We had a lot of machines at the newspaper that had proprietary boards. If we bought them, and it didn't resolve the issue, or we fried them, no returns. If we called a service tech in, and they fried them, no charge....
ECU price $6000
ECU Not returnable and no guarantee it will fix glow plugs.
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Understood, but if you cut the wire going to the glow plugs and splice-in an alternate source like you suggest, doesn’t the ECU detect a fault and derate?
Yes the older boards are easy with just transistors and capacitors. Once you get into Integrate Circuits it gets tricky fast.
