The symptom almost never names the system.
A harvester is an engine, a hydraulic circuit, an electrical network and a set of mechanical drives, all wrapped in one shell and all capable of producing the same complaint. Work out which one owns the fault, and the repair becomes obvious. Skip that, and you buy parts.
- Open 24 hours, seven days
- No hourly minimum
- Findings written down
- Measured, not guessed
One complaint, four possible owners
Take the most common thing anybody says on the phone: the machine has lost power. On a car that sentence has a fairly short list behind it. On a self-propelled harvester it could be the engine genuinely down on output, a hydrostatic drive slipping internally, a hydraulic circuit unable to hold pressure while the engine stays strong, an electrical fault that has quietly derated the machine to protect itself, or a mechanical drive so loaded by a seized bearing that everything upstream is working harder than it should.
Five different repairs. Five different price tags. And from the seat, all five feel close enough to identical that a reasonable person describes them the same way. This is what separates agricultural diagnostic work from most vehicle work, and it is why the first job is never fixing anything. It is deciding which system the fault belongs to.
Once that is settled, the rest usually follows quickly. Most of the expensive mistakes in this trade happen in the gap before it is settled, when somebody starts replacing the component the symptom seemed to point at and the machine goes on doing exactly what it was doing.
Good reasons to callA fault nobody can pin down, a second opinion before a large part goes on order, something intermittent, or a machine that quit with no warning at all.
The costWhat the job runs gets agreed before the truck moves, trip and diagnosis in one figure, and a fault found in ten minutes is billed as ten minutes.
Ground coveredNapa and Solano first, then Yolo, Sonoma and the Delta edge as the call warrants. See the areas we cover.
Isolation is what makes the answer cheap
The method is not complicated, but it has to be done in order. Each system on the machine gets a test that only it can pass, and the ones that pass get set aside. What is left is where the fault lives.
Say a header will not lift with any authority. Engine first: does it hold its revs under the load, and does the controller show a derate? If yes to the first and no to the second, the engine is exonerated and that whole branch closes. Hydraulics next: put a gauge on the test port and see what the circuit is actually making against what it should make. If the pressure is right, the pump and relief are fine and the problem is downstream at a cylinder or a valve. If the pressure is low, the question becomes whether the pump cannot produce it or something is bleeding it away, which is another short test rather than a guess.
Four or five measurements, each one narrowing the field. At the end there is a figure behind the conclusion instead of an opinion, and the difference matters most when the recommendation is an expensive component. Nobody should spend that kind of money on somebody’s hunch, including ours.
What gets tested
Which of these come off the truck depends entirely on what the machine is doing, which is why the phone call at the start does real work.
Controller fault histories
Stored, pending and active codes from engine and machine controllers, read with the conditions that were logged when each one set.
Hydraulic pressure and flow
Gauges into the test ports, because a worn pump, a bypassing valve and a leaking cylinder are indistinguishable from outside the circuit.
Electrical measurement
Voltage drop across suspect circuits, ground integrity and live signal values, which is where intermittent faults are eventually cornered.
Engine output checks
Fuel supply, boost, air restriction and exhaust back pressure, to establish whether the engine is genuinely weak or merely being asked for too much.
Mechanical drives
Belts, chains, sprockets, bearings and gearboxes checked for the drag and play that make every other system look like it is failing.
Heat and noise
Temperature at bearings, housings and coolers, plus where a noise originates and whether it follows engine or ground speed.
Hydraulic repair
When the isolation lands on the hydraulic side, the repair usually happens on the same visit with hose built on site.
Electrical repair
Grounds, connectors, harness damage and charging faults, which is where a surprising share of mixed-system symptoms finish.
What you saw is evidence nobody else has
Machine data is good at recording what a controller noticed. It is poor at recording the twenty seconds before that, and those twenty seconds are often the whole answer. The person who was in the seat is the only source for them, which makes that conversation the most productive part of many visits.
- What the machine was doingWorking hard, turning at a headland, idling, or starting cold. The condition it failed under narrows the list more than the failure itself does.
- Whether it built up or arrivedSomething that has been getting worse for two weeks is a different class of fault than something that stopped mid-row without warning.
- What was on the displayEven a partial reading helps, and a photograph of the screen is better than a description of it.
- What changed recentlyA service, a new implement, a fuel delivery, a repair. New faults following recent work are related far more often than coincidence would suggest.
- Whether anything still worksWhich functions are unaffected eliminates whole systems before anybody arrives, and it is the question most people are never asked.
Sometimes the finding is that nothing is broken
A fair number of these visits end without a repair. A machine feeling slow on a hot afternoon with a full load may be doing precisely what it was built to do. A derate that cuts power is frequently the machine defending itself against a condition it detected correctly, and the honest answer is to deal with the condition rather than defeat the protection. Saying that out loud is a worse sale and a better outcome.
If your machine is fine, I would rather tell you that and charge you for the trip than find you something expensive to buy.
Patrick Freeman, owner
Before you book a diagnostic visit
Anything below is quicker settled on the phone, and the line is open at every hour.
Two shops have already looked at it. Why would this go differently?
Because most repeat failures come from treating the symptom as if it named the system. If a machine has had a pump and then an alternator fitted and still behaves the same, the useful question is not which part to try next, it is which system was ever proven to be at fault. Starting again from measurement, with no attachment to the earlier theory, is often the shortest route left. Sometimes it confirms the earlier work and finds a second fault sitting behind it.
Do I have to have you do the repair afterward?
No. The findings are yours with the measurements behind them, and plenty of operations take the report and schedule the work themselves or through a dealer. Some ask us to continue on the same visit simply because the machine is already open and the tooling is there. Either is fine, and what you pay for the diagnosis does not change based on which one you choose.
Can anything be worked out over the phone before you come?
Frequently a useful amount. A clear description of what the machine was doing, what still functions and anything showing on the display can rule out whole branches before the truck leaves. Occasionally the call ends with a suggestion to check a level or a connection, which costs nothing and sometimes solves it. When the description points somewhere that needs a gauge or a meter, you hear that plainly along with the number.
The fault only shows up sometimes. Is it worth calling now?
Yes, and earlier is better than waiting for it to become permanent. Controllers log the operating conditions present when a fault set, so there is evidence to work from even while the machine behaves. Intermittent problems on equipment are heavily weighted toward connectors, grounds and harness sections that flex or heat, and those can be found and tested during a quiet spell. Waiting usually means it finally becomes permanent at the worst hour of the season.
Will a general scan tool not find this?
Sometimes, and sometimes it reports a clean bill while the fault sits somewhere it cannot see. A generic tool will often link to the engine controller and read emissions-related data while being blind to the machine controller running hydraulics, drive and implement functions. If the fault lives in that second computer the tool is telling the truth as far as it can see, which is the trap. Equipment-specific adapters and software cover both sides.
How much of the machine gets checked on one visit?
As much as the symptom justifies, and no more. Chasing a specific complaint is a focused job, usually a few hours. A whole-machine assessment before a season or before a purchase is a different and longer piece of work, and it gets quoted as such. What does not happen either way is a list of unrelated findings attached to a repair you called about, because that is how people stop trusting the report.
Describe the behavior, not the part.
The call reaches the mechanic himself. Tell him what the machine did, when it did it and what still works, and you will have a number and an arrival window before the call ends. If it can be sorted out on the phone, that is what happens instead.
HoursMonday to Sunday, 24 hours
Based inAmerican Canyon, CA
Where this leadsDiesel repair when the engine owns it, general field repair for everything else, and combine repair in season. Work is pictured in the gallery; contact takes the longer description.