hst cruise control works/doesn't work

[bluecrop]

we have a tc 45 d, 2 years old with 120 hours.
the cruise control is intermittent. there seems to be no set sequence that causes it to quit working.
wag (wild ***** guess) is that there is an electrical connection gone bad.
anyone have this problem before and have found a cure?

 

[LarryD]

Take a look at this thread- http://www.tractorbynet.com/forums/nh-owning-operating/111625-tc45d-cruise-control-problem.html

 

[jinman]

I would suggest that either the CC switch, CC relay, or brake pedal switch is the cause of your problem if the wire to the CC magnet is not rubbing a bare spot to ground. The relay is under the cowling at the front of the operator's platform. If you want to tackle that, I'll describe how to remove the cowling to check the relay. Let us know if you want to try this yourself. Follow the link that LarryD gave you and let me know if you need more help.

 

[RickB]

I would suggest that either the CC switch, CC relay, or brake pedal switch is the cause of your problem if the wire to the CC magnet is not rubbing a bare spot to ground. The relay is under the cowling at the front of the operator's platform. If you want to tackle that, I'll describe how to remove the cowling to check the relay. Let us know if you want to try this yourself. Follow the link that LarryD gave you and let me know if you need more help.

Could also be a faulty magnet (not uncommon), or an air gap too wide.

 

[jinman]

Could also be a faulty magnet (not uncommon), or an air gap too wide.

Yeah, I agree. The fact that it works sometimes and doesn't work at others is what I find most interesting. Most of the time with magnet problems, they fail completely, or with misadjustment they won't hold. It could be adjustment or it could be an internal magnet winding broken and making intermittent contact. This could be tough to isolate. If it were mine and I could not find an obvious problem, I think I'd replace the relay. But, that would be "Easter-egging" to some degree.

 

[RickB]

Yeah, I agree. The fact that it works sometimes and doesn't work at others is what I find most interesting. Most of the time with magnet problems, they fail completely, or with misadjustment they won't hold. It could be adjustment or it could be an internal magnet winding broken and making intermittent contact. This could be tough to isolate. If it were mine and I could not find an obvious problem, I think I'd replace the relay. But, that would be "Easter-egging" to some degree.

If had to start swapping parts without knowing for sure, I'd change the magnet without hesitation. But I would also adjust it closer to the plate first. I think an intermittent fault in a relay would be unusual. But it's all speculation.

 

[bluecrop]

thanks all.
will be checking it this weekend.

 

[h10doc]

THis is a common problem with the HST the brake switch needs to be adjusted two small screws under the left hand foot board the swith will slip out of adjustment and intermittly work. I'll try to get some pics for you are you can pm me and i'll give you my cell numder and walk you thru the adjustment.

 

[jinman]

thanks all.
will be checking it this weekend.

Just one more tip. . .

You don't have to have the tractor running to check the cruise control. First, release the parking brake (if it is ON), turn the key ON, press down on the HST pedal, and select cruise with the switch. You should hear a click and cruise should engage to hold the HST pedals where they are. Next, walk around the tractor and press both brake pedals at the same time. Cruise should cancel and the HST pedals return to neutral. Now, release the brake pedals and flip the tab up so the brake pedals can be depressed individually. Set cruise as before and then press one brake pedal at a time. Cruise should hold until you press both pedals at once.

If this all works, there is nothing malfunctioning with cruise except maybe magnet air gap. While doing this test, you can check how firmly the HST pedals are held while cruise is engaged. If they move easily, the magnet is weak or out of adjustment. If they hold firm, no adjustment is needed.

I have seen many relays over the years with intermittent contact problems, especially in inductive circuits like the electromagnet in the cruise control where arcing may occur. If you wish to replace the most expensive component first (The magnet as RickB suggests.) then you certainly may, but if I had an intermittent problem, I'd go for the relay possibly sticking or having dirty contacts. It's the lowest cost part of the two and most likely to have an intermittent problem in my opinion.

 

[RickB]

If you wish to replace the most expensive component first (The magnet as RickB suggests.) then you certainly may, but if I had an intermittent problem, I'd go for the relay possibly sticking or having dirty contacts. It's the lowest cost part of the two and most likely to have an intermittent problem in my opinion.

The real value of this thread lies in the troubleshooting suggestions. Poor or no troubleshooting leads to needless parts cost. The most expensive parts are the unneeded ones. My suggestion that the magnet may be at fault here is the result of the experiences of myself and the guys I work with. If I had to travel to troubleshoot this problem, I would not leave without a magnet in hand. Power relay failure in TC's is virtually unheard of. Without getting our hands on the tractor in question as I said in a previous post, it is all speculation.