Chapter 2- The Plug That Would Not Fit

The socket Katie was looking for was not under the dash of the tractor, because tractors do not have a dash in that sense, and when she finally found something that looked like a diagnostic port it was round and it had nine pins in it and her adapter would not have gone into it with a hammer.

She sat in the cab with the door open and a torch in her teeth and felt, for the first time in several years, completely out of her depth on something she had assumed she understood.

Two Different Standards

What she worked out over the following two evenings, from manufacturer documentation, two forums and rather more videos than were strictly necessary, is that road vehicles and agricultural machines took different paths and never converged.

Passenger cars and light trucks run a standard called OBD2, mandated in the United States from the 1996 model year, delivered through a sixteen pin flat connector, with fault codes written as a letter and four digits. Everything about it was designed to be universal, because the point of the mandate was that any technician anywhere could read any vehicle.

Heavy machinery went a different way. Agricultural tractors, combines, and heavy trucks communicate on a standard called SAE J1939, which is a network specification rather than a socket specification, and it is usually reached through a round nine pin connector of the type the industry calls a Deutsch connector. Faults are not written as a single code. They are written as a pair of numbers.

The socket on the pickup and the socket on the tractor. Neither one accepts the other's tool.

There is a second standard sitting alongside it, called ISOBUS, which is what lets an implement and a tractor talk to each other and share a screen. That matters enormously for a planter or a sprayer and it is not what this book is about, but a reader should know the word, because it explains why a tractor cab has more than one connector in it and why not all of them are for diagnostics.

A Pair of Numbers Instead of One

The part that took Katie longest to accept was the code format, because it is genuinely a better system and it looks at first like a worse one.

On the pickup, a fault is one code. Four digits with a letter. That code means one specific thing, and once you have looked it up you know what the truck is complaining about.

On the tractor, a fault is two numbers. The first identifies the component or the measurement the machine is unhappy about. The second identifies the way in which it is unhappy.

The same idea expressed two ways. The tractor's version carries more information.

So the same component can appear with several different second numbers, and each combination means something different. A sensor reading higher than it should is a different fault from the same sensor reading erratically, which is different again from that sensor having no electrical connection at all. On the pickup those would often be three separate four digit codes to look up. On the tractor they are one part number with three different failure modes, which is more informative once you stop expecting it to behave like a car.

It also means the numbers look intimidating and are not. Katie's advice to her father, once she understood it herself, was to read the pair out loud as a sentence. Part three thousand two hundred and fifty one, failing in mode zero. Then look up what part three thousand two hundred and fifty one is, which takes about four seconds on a phone, and what mode zero means, which is the same answer every time on every machine.

What the Tractor Actually Has On It

The other thing those two evenings produced was a proper understanding of what her father's tractor actually is, which he had never needed to know and which turns out to determine everything.

It is a 2015 machine, which puts it in the emissions category the industry calls Tier 4 Final. That is not a marketing term. It describes what has to be fitted to the exhaust, and on this machine it means three separate things in series: an oxidation catalyst, a particulate filter that traps soot and periodically burns it off, and a selective catalytic reduction system that meters a fluid into the exhaust to reduce oxides of nitrogen.

Every one of those has sensors on it. Every one of those reports to the engine control unit. And every one of those is capable of putting the machine into reduced power if it decides something is wrong, which is exactly the behaviour Vern had been describing since October.

For contrast, the other tractor on the place is a 1979 International 1086 that Vern's father bought new. It has a mechanical injection pump, a cable throttle and no computer of any kind. There is nothing on it to plug into and nothing for it to say. Chapter seven is about what that means for a buyer, and it is not entirely bad news.

The Question She Could Not Answer Yet

By the Wednesday, Katie knew what the socket was, what the protocol was called, how faults are written and what the machine had on its exhaust.

What she did not know was which tool to buy, and she wants readers to understand that this is where most people stop. It is not the concept that defeats people. It is that a search for a heavy duty diagnostic tool returns a forty dollar cable, a two hundred and fifty dollar handheld unit, a six hundred dollar Bluetooth kit with an annual subscription, and a five thousand dollar professional rig, all of which claim to do the same job, and there is no obvious way to tell which one will actually read a 2015 tractor of this brand.

It took her a day to work it out. It is the next chapter, and it is the most practically useful chapter in this book.

What She Got Wrong First

Two of those two evenings were spent going down a road that turned out to be wrong, and it is worth recording because a reader searching the same terms will go down it too.

Katie's first assumption was that there must be an adapter that would let her existing car dongle read the tractor, because that is how the internet presents the problem. There are a great many listings for a cable with a nine pin plug on one end and a sixteen pin socket on the other, at prices that suggest the whole thing is a twenty dollar issue.

Those cables are real and they work. What they do is route the network wiring from a tractor into a sixteen pin socket. What they do not do is change what is plugged into that socket. Her car dongle listens for the passenger vehicle protocol on specific pins. It hears nothing on a tractor because nothing is speaking that language, and the adapter cannot translate.

The second wrong road was assuming the tool had to be brand specific. Several sellers...

This curated preview is provided for personal reading. Copyright remains with Nobo Astoria.