Whether the circuit can deliver
A voltage drop test under load is a yes or a no about a specific path, and it does not depend on anybody's judgement. It is the single most decisive test in this trade and it takes twenty minutes.
The limits of the thing we sell
What a diagnosis cannot tell you
This website argues that measurement beats guessing, and it does. It is worth being equally plain about what measurement does not settle, because the gap between those two is where customers get disappointed by workshops that were doing their job properly.
A fault that is not happening cannot be measured
This is the big one. An intermittent fault is not a harder version of an ordinary fault; it is a different job. The work is not finding it, it is PROVOKING it — heat, vibration, water, load, whichever the history points at — and being instrumented in advance so that the moment it arrives is recorded rather than missed.
That takes longer, sometimes days, and it is why it is priced differently on the rate card. A workshop that charges an intermittent fault as an ordinary hour is either going to lose money on it or is going to stop before it has found anything.
Measurement is a photograph, not a forecast
A charging system that tests correctly today tested correctly today. It does not follow that the alternator has three years left in it, and nobody who tells you otherwise has measured that. Where something is marginal rather than failed we will say marginal, say what the reading was and what a good one looks like, and let you decide — which is less satisfying than a verdict and is the true position.
Nothing here is benchmarked against anything. Nothing on this site compares your vehicle to any other. We have not measured a population of your make and model, so we cannot tell you what usually fails on one, and a figure presented as if we had would be invented data with a percentage sign on it.
The history is evidence and we usually do not have it
Half of what is wrong with an old vehicle's wiring was done by somebody, at some point, for a reason that made sense at the time. A repair made with the wrong connector in 2019 is not visible as history; it is visible as a fault in 2026, and the difference matters when the question is "why did this happen".
Which is why the most useful thing a customer can tell us is what has already been done. It is not a confession and nobody here is keeping score.
And a fault can have more than one cause
Two marginal connections in the same circuit will each pass a casual look and fail together under load. A repair that fixes one and leaves the other produces a vehicle that is better and not right, which reads from the outside exactly like a workshop that did not fix it. Where that is a possibility it is said at the start rather than explained afterwards.
Nothing on this website names a fault on your vehicle. Not the intake, not the articles and not the telephone. A fault named from a description is a guess, and the whole argument for this trade is that a measurement is not a guess.
What an hour does settle
So that this page is not only a list of limits
Whether a component is being fed
Measured at its own connector rather than at the battery. This one sentence is the difference between replacing a module and finding out why it looked dead, and it is why nothing gets opened here before it is asked.
What a signal is actually doing
A scope trace is a fact about the signal, not an interpretation of a number the software rounded. It separates a sensor reporting nonsense from a sensor being supplied badly, which produce the same code.
$145 a workshop hour · $185 on site · agreed before it starts
Describe the symptom, or just telephone
The symptom check takes about three minutes and gives you a written summary of which circuits would be tested first and why, with the hours and the published rate against each. It is an indicative scope and not a diagnosis — nobody has seen the vehicle — but it is a better opening than a blank contact form. If you would rather skip it, the telephone works.