Find the fault. Then buy the part.
Electrical problems on heavy equipment get solved by testing, not by shopping. A scan tool says which circuit is unhappy. A multimeter says why. Parts thrown at a machine before both of those have spoken are usually parts you paid for twice.
- Open 24 hours, seven days
- No hourly minimum
- A price before work starts
- Machine controllers and engine ECMs
These machines live outdoors, and the wiring knows it
A pickup spends most of its life on pavement with the harness tucked up out of the weather. An excavator spends its life in mud, rain, dust and vibration, getting pressure washed at the end of it, then sitting in a yard for a fortnight. Every connector on it is a place for water to sit and corrosion to start, and every harness run is somewhere a clamp can let go and let the loom rub a frame rail.
That is why the odds on heavy equipment are so different from a car. On a machine that works outdoors, the fault is far more often a bad ground, a corroded connector or a chafed wire than a failed component. The component is what the code names, because a code describes a symptom seen from inside a controller. It is not a diagnosis and it was never meant to be read as one.
Getting that backwards is expensive. A sensor that costs real money goes on, the fault comes back a day later, and now there is a new part on the machine plus the original problem still sitting in a connector six feet away. We would rather spend the time with a meter first and buy one part once.
What we chaseNo-start and cranking faults, charging problems, intermittent shutdowns, warning lights, dead controls, wiring damage, and ignition and starting circuits on gas and diesel machines.
How it is billedWhat the job runs is agreed before the truck leaves, diagnosis included, with no hourly minimum on a fault that turns out to be a five minute fix.
TerritoryAnywhere in Napa and Solano as a matter of course, plus Sonoma, Contra Costa and Alameda depending on the machine and the day. Check the counties we run.
Grounds and chafe: the two things that hide
A ground connection does not announce itself when it goes bad. It corrodes slowly under its bolt, resistance creeps up, and the machine develops a personality: a starter that turns slower than it used to, gauges that flicker, controllers that reset when the boom moves, lights that dim when something else switches on. Every one of those looks like a different fault and all of them can come from one bolt with green powder under it.
Chafe is the other quiet one, and it is worse because it is intermittent. A harness rubbing a frame rail or a hydraulic line wears through the insulation over hundreds of hours, and the wire only touches metal when the machine is at a particular angle or the boom is in a particular position. The code that gets stored says the circuit was open. The wire looks fine unless somebody moves the loom while watching a meter.
Finding those takes voltage drop testing across connections that look perfectly clean, and moving harnesses by hand while the circuit is live and monitored. It is unglamorous work and it is the difference between a fault that is actually gone and one that comes back the following week.
A fault code names a circuit. It does not name the part. Everything worth knowing sits between those two sentences.
How we read a scan tool
Electrical work we do in the field
Nearly all of this happens where the machine sits. Electrical faults are one of the strongest cases for field service, because the machine usually has to be running and working for the fault to appear at all.
Fault code diagnosis
Codes pulled from engine and machine controllers, then traced to a cause with a meter. The code is the starting point, never the conclusion.
Sensor replacement
Pressure, temperature, speed and position sensors replaced once testing confirms the sensor itself is at fault rather than the circuit feeding it.
Wiring and harness repair
Chafed, burnt or broken wiring repaired properly with soldered or crimped joints and sealed insulation, then routed and clamped so it does not happen again.
Ignition and starting circuits
Key switches, relays, safety interlocks and starter circuits on machines that crank intermittently or refuse to crank at all.
Charging system repair
Alternators, regulators, cables and batteries tested as a system, so the part that actually failed is the one that gets replaced.
Full machine diagnostics
When the symptom crosses electrical, hydraulic and engine territory, the whole machine gets looked at instead of one subsystem.
Machines that sit are harder on batteries than machines that work
A lot of equipment in this valley works in bursts. A machine runs hard for a week, then sits for ten days waiting on the next phase. That pattern is rough on a charging system in a way that daily use is not, and it produces most of the dead-battery calls we take.
Two things happen while a machine sits. Controllers, telematics boxes and keep-alive memory draw a small current the whole time, which on a machine parked for a couple of weeks is enough to pull a battery well down. And the short runs in between never give the alternator the sustained time it needs to put back what starting took out. Batteries that spend their life partly discharged sulfate and lose capacity early, so the machine that gets used least is often the one needing batteries first.
The part worth testing is the parasitic draw. A normal standby current is small and measurable. A circuit that stays awake when it should not, or an accessory wired in badly at some point in the machine’s history, shows up immediately on a meter and explains years of unexplained flat batteries.
The rest is ordinary care that gets skipped: clean terminals, tight cables, a hold-down that actually holds so the battery is not vibrating itself apart, and charging output verified under load rather than assumed because the light on the dash went out.
Common questions on machine electrical faults
Intermittent faults are worth calling about while they are happening. Someone answers at any hour.
The code names a sensor. Does that mean the sensor is bad?
Usually not. A code tells you a controller saw a reading it did not expect on that circuit, which can be caused by the sensor, the wiring to it, a connector, a ground, the power feed or a genuine mechanical condition the sensor is reporting correctly. Testing the circuit before buying the part is the whole job, and it is why swapping parts at a code often leaves the fault in place.
Can you find an intermittent fault that only happens sometimes?
Often, yes, though it takes longer than a fault that is present the whole time. Stored codes and freeze frame data narrow it down, then harnesses get moved by hand with the circuit monitored to reproduce it. The best possible case is calling while the fault is actually happening, so if a machine acts up at a particular time of day, that is worth mentioning.
My machine keeps killing batteries. Is the battery the problem?
Sometimes, but a battery that dies repeatedly is usually a symptom. Parasitic draw while the machine sits, a charging system not keeping up, corroded cables or a loose hold-down all shorten battery life. Testing the draw and the charging output under load is what tells you whether you need a battery or a repair that will stop eating batteries.
Can wiring damage be repaired properly in the field?
Yes. Chafed and broken wiring is repaired with soldered or properly crimped joints and sealed insulation, then routed and clamped away from whatever wore through it. Twisted wire and tape is a get-home fix, not a repair, and on a machine that vibrates all day it fails again fairly quickly. We also look at why the loom was rubbing in the first place.
Do you have the software to talk to my machine?
Diagnostic tooling and adapters cover engine and machine controllers across the common equipment brands, and that handles the large majority of what comes up in the field. Some proprietary functions are locked to dealer software, and when a job needs that we say so plainly rather than spending your money finding out slowly.
How is diagnostic time charged?
You hear what it’ll cost before the truck leaves, with the visit and the diagnostic work in one figure and no hourly minimum. If the fault turns out to be a loose ground found in ten minutes, that is what you pay for. Patrick built this business after watching people get quoted one number and billed a bigger one.
Machine dark? Let us test before you buy.
Tell us the machine, any codes on the display, and what it does and does not do when you turn the key. Most electrical calls can be narrowed down considerably over the phone, which means the right tools and likely parts come out on the first trip.
HoursMonday to Sunday, 24 hours
Based inAmerican Canyon, CA
See alsoHeavy equipment field service · Jobsite repair · Wheel loader repair · Gallery