TC45D won't start and is winning

[Su7]

I've been fighting with my TC45D now for a few days more than I care to admit. It all started with not starting. I immediately searched these forums and found several items to check. First I replaced #2 fuse which had been blown. I replaced it with the recommended 10A NAPA CB version and still no luck. I then flipped it with #1 fuse, also 7.5A, since I didn't know if it was tripping since the NAPA item resets itself. The fuse does not blow so I know I don't have a direct short. I then tested the starter jumper test and it turns over just fine.

I also double checked my seat jumper that I installed many months ago and it is still functioning just fine. The tractor is in neutral, PTO not engaged and the parking brake is engaged. What am I missing? What other safety circuits could come into play? Do I now have to jumper or open all the safety switches to track down the culprit? What would you do since I'm running out of options and patience?

Thx,

Stan...

 

[jinman]

Stan, as you found out, the starter will work fine if you jumper 12 vdc to the solenoid. I'd bet that if you measure that solenoid voltage from the starter switch, you'll find the voltage is probably 10.5 - 11 vdc instead of 12 vdc. That's because the start relay contacts are getting dirty with age and dropping too much voltage due to excessive contact resistance. There are only two things between the power from #2 fuse/breaker to the starter solenoid:

1. The neutral sensing switch - It's contacts are in series with the power.

2. The neutral start relay - This relay's coil works off the ignition switch. When the coil energizes, the power from the neutral sensing switch goes through the relay's contacts and directly to the solenoid.

If your seat switch is faulty, the engine will still turn over, but not start. The only things that can stop the engine from turning over are the neutral switch and the PTO safety switch. The PTO safety switch just keeps the start relay listed above from energizing. It is NOT in the power path to the solenoid.

Just to make a swag, I'd guess the Neutral Start Relay (K1) is your culprit. It's the relay pointed to by ref #9 in the attached diagram. To get to that relay, you have to remove the left side black cowling under the steering wheel. I believe the relay no. is 86529089 and is about $20 from New Holland.

Here is why fuse #2 sometimes blows. The solenoid has two coils inside. One is high-current and the other is low current. The high-current one is supposed to energize for only a short time to pull-in the solenoid. When the solenoid pulls in, it switches over to low current. If the power to the solenoid is not enough to fully pull-in the solenoid, it stays in high current mode and blows fuse #2. That's why a resetting circuit breaker works so well. I have never replaced the start relay on my tractor and it acts up from time-to-time, but after about 8 or 10 attempts to start, the solenoid fully engages and the tractor starts. One of these days I'll have to replace the start relay I'm sure.