NH TC40A Starting problem

[Bencaruthers]

My TC40A will crank but wont start. Need some help troubleshooting. This is how far I’ve got:

Checked the fuel lines, changed the fuel filter, manually bled the the system at the injector pump bleed valve. Did not fix the prob.

Unplugged connector at Fuel Shutoff Solenoid, jumped from battery direct to solenoid, cranked right up. Checked volts to the light blue line going to the solenoid, no volts. So narrowing it down at this point.

Traced connecting line back to the #4 relay, checked for continuity with ohmmeter, good there ( surprising since mice had made a nice home in there).

Thought maybe a bad relay, so switched #4 relay with #1 relay, but no change.

Got on here, read a ton of good info. Saw where it could be the seat switch or bypass wiring.

Unplugged the seat switch and tried jumping connection with a piece of copper wire. No change, and still no power to connector at solenoid.

Heading back to the farm today to continue working on it. Any help would be greatly appreciated!

Could it be the 8amp circuit breaker on the buss bar? Possibly a problem with the ignition sending power?

Thanks in advance.
Ben

 

[dlctcg]

So, the seat switch and the parking brake switch are the ones that control the fuel solenoid to shut off. Being you already jumpered seat switch for testing... did you make sure the parking brake was set & the Dash Light was on? The lever needs to be pulled up to engage the switch...

These two switches will not stop the engine from turning over which the tractor seems to be doing...

The #4 Relay is a latching relay & sounds like to tested & even swapped it with a known good one... not sure your model is the same config as ours but check for the Neutral Start Relay & make sure its good & wires are not chewed... Relay #9 in this PDF... but this is for a TC40D so just confirm for your tractor...





If the any of the follow 3 were the issue, 8amp breaker, the neutral safety or PTO safety switch the tractor will not turn over / crank. So I think the breaker is good...

Definitely double check the wiring for chewed wires... mice are known for building nests there & messing things up... so look really good...

 

[Bencaruthers]

Thanks for the quick reply! Good info! Yes, that’s the same diagram in my owners manual.
Yes i switched the relay with one that I confirmed good.

Haven’t checked the #9 neutral start relay yet. Does that send a signal directly to the solenoid, or to the #4relay which in turns send signal to solenoid?

Ill check the #9 relay, the parking break switch, and look for chewed wires again and let you know.

thanks again!

 

[Bencaruthers]

Ok, so parking brake set and dash light is on. Assuming that means the safety switch is ok. Seat switch still jumped, and still no power to solenoid. Checked and cleaned #9 relay and wires. All looked ok. Swapped #8 and #9 relays as a check, still no power to solenoid.

Could it be the Operator Safety Module? I traced the light blue line to the #4relay with ohmmeter, looked fine. Traced the white wire to the seat switch, looked fine. Could it be a bad circuit board in that module(assuming that’s a circuit board in there)?

 

[Bencaruthers]

Alright, figured out the problem!! It is in fact the Operator Safety Module. Either the connectors, or the actual board inside. Jumped across the safety’s from the blue wire connection(to solenoid) directly to black wire connection(ground) in the module itself....turned the key and and got power to solenoid!!
Feels good to get that fixed! Thanks for the helpful tips dlctcg! That definitely helped with figuring it out.

 

[dlctcg]

Glad you could trace it down...

 

[thclimer]

And thanks for letting us know what you found so that others in the future can possibly benefit.

 

[Bencaruthers]

No problem. This forum is a great source of info!
I don’t really want to leave the Operator Safety Module jumped since it bypasses the seat safety and the parking break safety features full time(wouldn’t recommend jumping safety’s). So my only other question now is, do I buy a new OEM Operator Safety Module for $65 plus shipping....., or is there a reason I couldn’t just use a cheap Bosch relay that could basically perform the same function?

 

[DieselMonk]

There is another safety switch at the PTO lever. That’s what my old TC55DA’s problem was.

 

[greg0145]

I'm going to tag on to this thread...
My TC40D starter does not engage. When I turn the key to the start position the PTO On indicator is also illuminated. I've only had the tractor for 15 or 20 years so I don't recall if that light is supposed to be on at any time other than when the PTO is engaged. I jiggled the PTO handle and checked the parking brake and the range selector. Has anyone had a problem with the PTO switch and how do I find it? Or is there a bundle of wires under the instrument panel or behind cowling below the steering wheel that I should be checking first?

 

[showcattle]

I'm going to tag on to this thread...
My TC40D starter does not engage. When I turn the key to the start position the PTO On indicator is also illuminated. I've only had the tractor for 15 or 20 years so I don't recall if that light is supposed to be on at any time other than when the PTO is engaged. I jiggled the PTO handle and checked the parking brake and the range selector. Has anyone had a problem with the PTO switch and how do I find it? Or is there a bundle of wires under the instrument panel or behind cowling below the steering wheel that I should be checking first?

I don't know if the TC40 is the same, but on ours, there is some connectors in the left rear wheel well. Hauling firewood, one of ours got pulled loose and PTO light was on, causing a no start situation.

 

[thclimer]

I'm going to tag on to this thread...
My TC40D starter does not engage. When I turn the key to the start position the PTO On indicator is also illuminated. I've only had the tractor for 15 or 20 years so I don't recall if that light is supposed to be on at any time other than when the PTO is engaged. I jiggled the PTO handle and checked the parking brake and the range selector. Has anyone had a problem with the PTO switch and how do I find it? Or is there a bundle of wires under the instrument panel or behind cowling below the steering wheel that I should be checking first?

The following post may help with your issue if you have not already read it:

My New to Me TC40D- Dilemma, fuel solenoid

I'm also attaching some pages from the manual which should help you locate and test you PTO switch, do you also have a MID PTO?

 

[dlctcg]

@greg0145 First thing to do is Check your #2 Fuse... If Fuse #2 is blown tractor will not crank & PTO Light WILL be illuminated.... Check that first... very common problem on the TC's

 

[dlctcg]

Here is a pic of the Fuse Block....

 

[greg0145]

Problem solved! Fuse #2 was burned out. I put in a new one and everything is working fine. Unfortunately it wasn't the first thing I checked because I was impatient to solve the problem before everyone offered excellent suggestions. Thank you showcattle, thclimer, and dlctcg for the links, references and guidance!

 

[dlctcg]

@greg0145 - Glad you found it... If it continues to act up, which is known to happen on the TC's as they get older do to resistance in the wiring & connectors. You can either get a auto-resetting circuit breaker.... or the better option in my opinion is.... to modify the starting circuit by adding a simple relay so the starter solenoid get direct voltage every time. Did it to ours... works great..

Pic of where I mounted the one on our TC40D


Not my design... Was posted on TBN & is a great guide on what needs to be done...

 

[thclimer]

@greg0145 - Glad you found it... If it continues to act up, which is known to happen on the TC's as they get older do to resistance in the wiring & connectors. You can either get a auto-resetting circuit breaker.... or the better option in my opinion is.... to modify the starting circuit by adding a simple relay so the starter solenoid get direct voltage every time. Did it to ours... works great..

Pic of where I mounted the one on our TC40D
View attachment 707524

Not my design... Was posted on TBN & is a great guide on what needs to be done...

I also modified the starting circuit to my TC33D by adding the relay because on numerous unsuccessful start attempts. After the modification it has started every time.

 

[DieselMonk]

Don’t jiggle the leaver, use force and bang that thing up and down. Anyway… thats how I fixed mine when it acted up like once a year. Usually after 3-4 times smacking the leaver in and out hard, it worked for the rest of the year.