316(Onan) No power to coil.

Could be a partial problem, but that ignition circuit also involves the safety switches (seat, neutral, and later serial numbers the brake switch). Have you check those operational for opening/closing, wiring to the switches for for breaks, cuts, broken insulation allowing shorts to metal? Also check the PTO switch, one side is to actually power the PTO clutch, the other side is used in the safety circuit too. Do you have the TM for the tractor?

I do have the TM1590 manual. Wouldn't the safety switches not let it crank over? I could be wrong. It cranks over it's just that it wont light off. The seat switch is jumped, and neutral switch works. It was running and it shut off while driving it. I have a good feeling a wire came loose. I'll look into it deeper tomorrow.

If you get to section 240 group 15 page 4 explains the ignition, in short (power for the coil/electronic ignition module comes off pin 2 of the large molex connector which has 10 wires on it). Have you checked for a voltage on the + of the coil going from 12 volts. See section 240 group 20 pages 14-18. Check the molex connector (3 wire) there may be a problem that carries power for the coil/ignition module there (molex pins/barrels). If no voltage the TDCM is saying that it is not safe to operate, caused by the conditions listed. Now if you can be be assured that the switches and their wiring is intact and operating then there is most likely a fault in the TDCM area. You will need to pull the two connectors apart. Clean the pins and barrels in the connectors, apply dielectric grease and reassemble. Then you can test the TDCM according to instructions in section 240 group 20 pages 23-25 (items 4e-4n)

The P218 ignition is solid state and this consists fo 2 pieces, both under the flywheel - these two pieces are a known failure point if you still have the OEM ignition module and associated timing ring. The test for this ignition system is contained in the Onan P218 engine repair manual that can be easily downloaded. I would test this as well as the coil (the coil is also a common failure point, especially if it was treated improperly), and then if it passed the tests, I would wire the engine directly to the battery (bypassing the TDCM) and attempt starting the engine - it should start if the ignition module,timing ring, and coil are good. To do this, you need to supply 12 volts to the engine through the engine-to-tractor connector. There's one wire to the oil pressure sensor, 1 wire to the voltage regulator, and one to the ignition system - this is the only one you need to have connected for this test. To stop the engine, just disconnect the connection to the battery. In addition, you'll need to wire up the starter directly from the battery, but only until it starts. If you need a schematic for this, I'll be glad to draw one and post it here.

JD316Fan said:

I do have the TM1590 manual. Wouldn't the safety switches not let it crank over? I could be wrong. It cranks over it's just that it wont light off. The seat switch is jumped, and neutral switch works. It was running and it shut off while driving it. I have a good feeling a wire came loose. I'll look into it deeper tomorrow.

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One of my 318's had this problem and for a while I could restart it after it cooled down. All my problems went away once I replaced the ignition control module and associated timing ring. This replaces the mechanical ignition points and can fail temporarily from heat or completely from stress. The coil and condensor for this is different from the one used for mechanical points and it's also wired differently, so for your testing and operation, make sure you follow the wiring diagram, otherwise the coil won't last long.