Blowing 10A Fuse- TC33DA

[Ramstack]

Recently I had an issue where I tried to start the tractor (after I just had been using it without any issues at all) and it wouldn't start. I checked the battery and it was good. Fortunately the next thing I checked was the fuses and found that the 10A fuse that is wired into I believe the engine start safety equipment as well as the alternator.

I thought it was kind of just a fluke the first time. However, it happened again this last weekend. I replaced the fuse like I did the first time and it blew right away as I tried to start the tractor. The tractor doesn't even turn over before the fuse blows. As soon as you turn the key to the start position the fuse pops. I replaced that fuse and the tractor then started up for me.

I am assuming that there is a short somewhere that is causing me to blow this fuse but I am hoping someone out there might be able to point me in the right direction before I try going through everything on that specific circuit hoping to find something obvious.

I did recently (well might be a month or more ago now) have the tractor in for service where they were required to split the tractor into three pieces, not sure if something might have been partially damaged during that work or not.

Any assistance you can provide would be greatly appreciated.

Thanks!

 

[thclimer]

I can tell you for sure the ignition switch on my TC33D was a very poor design, mostly plastic pieces with a few contacts. Mine melted and I replaced it with one from a NAPA auto parts store like another TBN member had done.

Take a look at the following post:

http://www.tractorbynet.com/forums/nh-owning-operating/109372-tc33d-glow-plug-problem-fixed.html

 

[SteveInMD]

I think there are two likely suspects here. The ignition switch or the "insufficient voltage at the starter solenoid" problem.

Here's a post of mine from another thread...


I believe many of our tractors suffer from a problem with the circuit that sends power from the key to the starter solenoid. The circuit has many safety interlock switches. It seems that as the tractor ages a dirt or corrosion at these switches creates a little resistance at each one. Eventually you end up with insufficient voltage at the starter solenoid to trigger it. You may first notice it after the tractor sits for a bit and the battery is not at 100% charge. A battery boost will increase the voltage enough to get it started. The lower voltage will increase the current draw on this circuit and can blow the fuse. However I've blown fuses even with a full charge.

There is an elusive service bulletin on the subject that I have yet to get a copy of. Basically the fix is to add another circuit that sends power directly to the solenoid. You just use a relay at the end of the safety interlock circuit that controls the new circuit. This fix does not eliminate any of the safety interlocks. It only takes a few volts and very little current to trigger the relay so the low voltage and current in that circuit no longer matter.

I believe if you are having any starting problems you need to complete this fix before trying to diagnose the problem.

 

[moonstruck]

I had the same problem with mine. Called the dealer and they said to go to a NAPA dealer and get a 10 amp circuit breaker to replace the fuse. They are about $6.00 as I recall. Slides right in the fuse slot and it solved the problem.

 

[SteveInMD]

The circuit breaker is a good temporary work around since you don't have to replace so many fuses, but it doesn't actually resolve the problem permanently.

 

[RickB]

The circuit breaker is the New Holland recommended solution for this concern. It can absorb the instantaneous amp surge sometimes occurring at startup without tripping. A properly sized fuse doesn't do that. An oversized fuse has other drawbacks. Install the CB and be happy. If there is some other problem creating a large amp draw, the CB will trip. I have yet to experience that.

It should also be noted that the starter solenoid coil voltage does not pass through the various safety switches. The switches complete a ground path for the starter relay coil.

 

[SteveInMD]

I'm confused here. Please help. NH issued a service bulletin with the fix I described. As far as I know the starter solenoid coil is the same things as the starter relay coil, right? Weather the the safety switches are in the ground path or positive side, it's all the same circuit so it really doesn't matter which way the current flows. If you don't have a good ground path you can end up with low voltage in the circuit.

 

[RickB]

I'm confused here. Please help. NH issued a service bulletin with the fix I described. As far as I know the starter solenoid coil is the same things as the starter relay coil, right? Weather the the safety switches are in the ground path or positive side, it's all the same circuit so it really doesn't matter which way the current flows. If you don't have a good ground path you can end up with low voltage in the circuit.

The added relay you are referring to applies to tractors built prior to the relay becoming a production change IIRC.
My post concerning the NSS(s) providing a grounding path for the start relay is not anecdotal; it is in response to your comment that the NSS(s) pass the current that energises the starter solenoid. That is NOT the case in tractors equipped with the start relay at or after production. The addition of the start relay has not eliminated the need to replace the fuse in questiion with a CB.

 

[SteveInMD]

So that means he already has the relay. Good to know. I didn't realize you still needed a CB with the relay fix in place. I think there are lots of people out there without the relay that have start circuit problems. A CB wont be a long term answer for them.

 

[RickB]

I'm confused here. As far as I know the starter solenoid coil is the same things as the starter relay coil, right?

No, the starter solenoid coil is integrated into the starter solenoid, bolted to the starter. The start relay coil is integrated into the start relay fastened under the cowling. The respective current draw of these coils are quite different, which is at least part of the core of this topic. There are many tractors out there that start fine with or without the relay, and with or without a circuit breaker. To say installing a circuit breaker is not a permanent solution is inaccurate, in my experience.