I have a TC40DA I am trying to sell for an elderly relative. The tractor will only start by jumping the starter ‘trigger’ wire off of the main starter power. All tractor functions work fine otherwise. I haven’t dug too deep but all the safety switches seem fine. PTO disengaged, in neutral, parking brake on, sitting in seat. I can hear a slight click behind the dash but don’t know where to start to look next. Anything common on these tractors that causes this problem? Fuses are also fine behind the instrument cluster. I’m thinking a bad relay or bad wire from the relay to the starter solenoid. I have reasonable automotive repair experience but know little about tractors and I’m a bit reluctant to start tearing it apart. Any suggestions are much appreciated.
New Holland TC40DA starting issue
- Thread starter Willjayc
- Start date
dlctcg
Platinum Member
The very first thing is I would check to see if you are getting any voltage at the Starter Solenoid when you turn the key to START... If you see voltage when you turn the key you the START position but it is less than 12V this will definitely cause an no-start / inconsistent starting issue.
Then:
- I would test the starter switch - voltage passes through it for all the above safety switches prior to getting to the starter solenoid lug..
If you are getting 12V at the starter solenoid then I would test you battery cables - These were a common problem on older NH machines where they would corrode internally even if they look fine. The corrosion would cause resistance in the cable so you will have voltage (like the 12.8V you are seeing) but they will not supply the required Amperage.
Then:
- I would test the starter switch - voltage passes through it for all the above safety switches prior to getting to the starter solenoid lug..
If you are getting 12V at the starter solenoid then I would test you battery cables - These were a common problem on older NH machines where they would corrode internally even if they look fine. The corrosion would cause resistance in the cable so you will have voltage (like the 12.8V you are seeing) but they will not supply the required Amperage.
No power at starter solenoid when ignition in start position. Main starter power is 12.8v. Jumping the starter main power to starter solenoid starts tractor and it runs fine (used for several hours yesterday) I’ve just checked the ignition switch. Seems to function properly. Left most red wire and 3rd red wire from left has 12v incoming, power to orange when key in on position, power to white when in start position. (Pic below). I will start chasing the white wire to see where it goes next….
Relay is good. Also if anyone is ever wondering, relays are on the lower left side of steering column. The 2nd relay from the back is the starter relay and white wire closest to the back is the power from the key (where I am pointing in the picture).
the old grind
Super Member
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- Jul 21, 2012
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- 5,067
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- Mid-Michigan
- Tractor
- NH T-1520 HST, NH TC33DA HST, Case DX26 HST, .Terramite T5C, . NH L785
I've downloaded as many digital as payed >$150 for printed factory service manuals. Kept on a pen drive I print pages as I need 'em. Instant access & has bailed my butt the day of a breakdown. Here's an example of a complete pkg similar to the last two I bought. Many are ~$25-40 for CUTs. It's a few bucks but you get a lot.
Thanks T.O.G. I’m hoping not to have to buy a manual as it isn’t my tractor, I’m fixing it for free (for a relative) and it is being sold.
It looks like something is going on with the wires coming to the relay mentioned above. Power from the key comes into pin 85. This makes me think pin 86 should be the ground to trigger the relay and make a connection from pin 30 to 87. But pin 85 wire goes to another relay, (relay #7 I think in illustration below) and is not grounded when I test using ohm meter. The other two wires join a main harness and head towards the back of the tractor (or into the abyss as I think I will henceforth call it). I’ll dig deeper another evening. Starting to wonder if it is related to the PTO safety switch…. I’m so glad NH has decided to make all these wires white with no stripes or identifiers whatsoever, it makes them so fun to follow!
It looks like something is going on with the wires coming to the relay mentioned above. Power from the key comes into pin 85. This makes me think pin 86 should be the ground to trigger the relay and make a connection from pin 30 to 87. But pin 85 wire goes to another relay, (relay #7 I think in illustration below) and is not grounded when I test using ohm meter. The other two wires join a main harness and head towards the back of the tractor (or into the abyss as I think I will henceforth call it). I’ll dig deeper another evening. Starting to wonder if it is related to the PTO safety switch…. I’m so glad NH has decided to make all these wires white with no stripes or identifiers whatsoever, it makes them so fun to follow!
the old grind
Super Member
- Joined
- Jul 21, 2012
- Messages
- 5,067
- Location
- Mid-Michigan
- Tractor
- NH T-1520 HST, NH TC33DA HST, Case DX26 HST, .Terramite T5C, . NH L785
I had a recent similar starting issue and when checking the switches IIRC it was the PTO or brake switch, under the left fender and not accessed easily from front or rear. There are plenty of 'em. Anyway, the switch seemed stuck and I gave it a shot of Blaster and worked it a little. Tractor is an '04 & has spent a fair bit of its life parked out in the elements. Good luck and keep us up on what you find .. or don't. 
Checked the seat, PTO and brake switch tonight. All are working properly according to the multi meter and dash lights. Charged the battery and still no power to the starter solenoid. Every other electrical component on the tractor seems to work fine. And jumping the starter via the solenoid and main power will start the tractor and continue to operate normally. I’ve traced the wire everywhere I can see it to inspect but can’t see any issues. Does anyone know where the wire from the solenoid comes from? I Can’t trace it everywhere as it is in a casing.