TC35D cuts out or won't start after getting hot

[srodster]

Recently the last couple months, my '03 TC35D (1400 hrs) when driving along sometimes cuts out (but never shuts off) and most recently when after mowing for 2 hours or so, and I shut it off, it won't start. I did some digging and trace back on the wires. When I run a hot jumper to the starter solenoid (white wire), it starts every time. So, I pulled the "spade" off the solenoid and checked the voltage when I turned the key to start it. It would fluctuate at 7, 5, 8, 3 volts..., very erratic. So, I traced the white wire that attaches to the solenoid on the starter and it goes to a 12v timer apparatus that has multiple functions, one of which is the glow plug activation, as well as the wire to the starter. If I don't have the 12 volts on the white wire when I try to start the tractor, guessing I need a new "timer apparatus", or is there something upstream that I should look at. I took the back off of the timer and saw a small computer board with capacitors, rheostats, transistors, and lots of solder joints. I couldn't tell the any joints had cracked, but since it occurs when it warms, guessing something may "open" when it shouldn't. Does that make sense, and logical trouble shooting? I'll contact the dealer to see if that is the appropriate part I should be looking at..... any thoughts appreciated.

 

[Harry in Ky]

The dealer will be happy to sell you a new one, no doubt. Will that solve the problem? Possibly, but who knows?

Depending on the price of that little jewel you might want to consider adding another power source to the wire going to the starter. Something like a simple push button supplying full battery voltage to engage the starter when the little black box won't do it.

 

[WM75Guy]

Could be the starter switch is getting hot causing voltage fluctuations. Probably the cheapest part to start with.

 

[srodster]

I did order the glow plug timer, since it has multiple functions and is one device responsible for getting the voltage to the starter solenoid. The part number for it is SBA385870301. Randy, curious if you know the "starter switch" part number you referenced? (In case the glow plug timer doesn't solve the issue.)

 

[WM75Guy]

Looks like it has been discontinued. Might call Messick's and see if there is an alternative.

 

[WM75Guy]

The NH Parts website says this is the substitute.

 

[nyone]

I believe that's just the glow plug timer. Type the NGK model number into amazon. I got one shipped for $14. There is a starter relay mod you can do I believe to help the amps flowing through that circuit.

 

[dlctcg]

@srodster - So before you put the new Glow Pug Timer in I would check a few things... (I personally hate throwing parts at something to see if it works... rabbit holing gets expensive with tractor parts...)

If I don't have the 12 volts on the white wire when I try to start the tractor, guessing I need a new "timer apparatus", or is there something upstream that I should look at.

First thing:
When you turn the key to the run position (not start / crank) does the glow plug light come on & then go off after a 4-6 secs? If so the timer is probably working correctly

So, I pulled the "spade" off the solenoid and checked the voltage when I turned the key to start it. It would fluctuate at 7, 5, 8, 3 volts..., very erratic

You are correct that it is very erratic & I can tell you that the tractor will not turn over unless it is getting 12V. This is not that uncommon on the NH TC series & kind of a known issue... (more on this in a min)

You already troubleshot part of it but proving it will crank & start when you put 12V directly to it; which means all safety switches are most likely working, so I would look at 2 different things prior to replacing the glow plug timer.

1st: I would test your battery cables, even if they look great, they are known to corrode internally on these NH's & cause a lot of resistance on electrical circuit, This may be one of the issues in regards to your statement:

Recently the last couple months, my '03 TC35D (1400 hrs) when driving along sometimes cuts out (but never shuts off)

2nd: As nyone said... I would definitely look at doing the Starter Relay Modification. That starter circuit is known for causing that exact "erratic" voltage problem overtime on the TC's. There is no downside to doing the mod; only positive results & very well could completely resolve your issue. (I would do the Mod either way).

Both the Battery Cable Testing & the Starter Mod procedures are well documented on TBN (I know I (& others) have posted them both multiple times... but if you need them let me know. (this is already a long post... lol)

Hope this Helps

Here is a pic of where I installed ours on the TC40D:

 

[tmeric7]

So, I traced the white wire that attaches to the solenoid on the starter and it goes to a 12v timer apparatus that has multiple functions

I believe that the timer/relay has one function: to energize the glow plugs. But it does this under two circumstances: (1) When the key is turned to the "run" position for a certain amount of time (about 5 - 10 seconds, depending on tractor model), and (2) whenever the key is turned to start. So the timer/relay is energized when you are starting the tractor, but the signal the starter solenoid receives from the key switch does not pass "though" the timer relay. There are multiple pathways. I don't think replacing this unit will affect your voltage at the starter solenoid spade.

There is a starter relay mod you can do I believe to help the amps flowing through that circuit.

I would definitely look at doing the Starter Relay Modification

I typically agree with these comments. Classic issue... several of us have dealt with it. Many recourses on TBN if you search around. Won't hurt anything, can only help. But I think possibly it may be a short instead.

I think this because the problem began while hot. You also said it would "cut out" without shutting off. I guess you mean the engine is missing occasionally? The starter relay mod won't address that. And a short is the one thing I can think of that addresses the missing and the no-start, especially while hot. Along those lines, it could certainly be a shorted or malfunctioning key switch (as noted above). Others threads have said that the OEM switches aren't great. I already replaced mine with a NAPA part.

 

[nyone]

A short would typicaly blow a fuse and wouldnt only be a short when hot. High resistance can how ever and theres alot of contacts involved in the start/run circuit.

You checked all your safety switches I assume? Some times the easiest way to diag is to jump around them temporary until the problem is found.

 

[dlctcg]

High resistance can how ever and theres alot of contacts involved in the start/run circuit.

^^^ Completely agree - I think he should definitely look at doing the starter relay mod... No down side.
Also this is why I suggested test the battery cable above - when they corrode they can have a lot of resistance that cause all sorts of issues like the OP is having when the tractor is running hot.

 

[srodster]

Thanks to everyone for their comments. I believe the issue has been solved w/ the new glow plug timer apparatus, since it has multiple functions besides the glow plugs. The white wire in my original message on the glow plug timer goes directly to the starter. So, I received the new timer, and put it on. I measured the voltage on the white wire where it clips onto the starter and I get 10 to 11 volts, much more consistent than with the old part. I realize I should have a solid 12v and maybe I do, but the resistance in my alligator clip connections to my meter could be why it's not a sold 12v.

I'll attach a couple photos of the timer, and you can see it has a few capacitors and some resistors, and a whole lot of solder joints at the board. So, since this only occurs when it gets hot, I'm guessing one of the solder joints opens up or has a crack preventing it from starting.

I have run the tractor now for about 3 days, and a couple hours each day. Weather has been in upper 90's, and heat index over 100F, so I know it's getting hot enough. Thus far, it has started up each time after being shut off. We'll see how she goes with more time.

 

[MRTOES]

Erratic running sounds like what used to be a condenser. Sometimes now called igniter sometimes hidden anywhere on a mower, on the coil or maybe on that board. Nothing should be going on at the starter other than the power is initially picked up there off the large terminal and usually sent to the fuse box/switch which then sends start back to the solenoid to start but the engine should run with all that disconnected as long as the fuse box and switch gets power.

 

[nyone]

Erratic running sounds like what used to be a condenser. Sometimes now called igniter sometimes hidden anywhere on a mower, on the coil or maybe on that board. Nothing should be going on at the starter other than the power is initially picked up there off the large terminal and usually sent to the fuse box/switch which then sends start back to the solenoid to start but the engine should run with all that disconnected as long as the fuse box and switch gets power.

Its diesel so dosnt have a coil, condenser or high voltage ignition system.