Automotive and diesel
Electrical Circuits, Switches and Electronics
Electrical faults are diagnosis work, not parts work. A short, a chafed harness or a bad ground can present as three unrelated symptoms, and finding it is most of the job.
What it usually turns out to be
You do not need a diagnosis to call. Describe what it is doing and we will tell you whether it is a shop job.
The battery is flat every few days and nothing was left on
A parasitic draw: something is staying awake that should go to sleep. Finding it means measuring the draw and then pulling fuses one at a time until it drops, which is patient work rather than clever work. It is very hard to do at a roadside and straightforward in a shop.
Three unrelated things stopped working at once
That is usually a ground rather than three faults. Circuits share grounds, so one corroded connection can take out a tail light, a window and a gauge together. The pattern of what died is the clue and it is worth listing everything, even the parts that seem irrelevant.
It works when it is dry and plays up when it rains
Water finding a chafed harness or a connector that has lost its seal. Intermittent-when-wet is one of the more findable faults once somebody can recreate it, and it is exactly the kind of thing that needs the vehicle for a while rather than for an hour.
A window, a mirror or a seat has stopped moving
Switch, motor, or the wiring between them, and they are easy to tell apart with a meter. Worth checking the switch first because it is the cheapest of the three and the one that gets used most.
The dash lights up like a Christmas tree, or a gauge reads nonsense
Often a supply or a ground rather than a set of failed modules. We read the codes across the vehicle rather than just the engine, because a communication fault shows up as everything complaining at once.
What we do
- Electrical short and parasitic draw diagnosis
- Computer controlled circuit repair
- Harness damage repair and rewiring
- Power windows, doors, seats and antennas
- Cruise control repair
- Dash gauge and switch service
- Turn signal, flasher and headlight circuits
- Wiper and washer repair
- Keyless entry and key fob programming
What we do not do here
- We do not do dealer-level module programming or make-specific coding, and we will tell you before you leave the vehicle rather than after. Some modern replacements only come alive with software only the dealer has.
- We do not do ADAS calibration. If your vehicle has cameras or radar behind the glass or in the bumper, work around them needs recalibrating properly and that belongs somewhere equipped for it.
- We do not do hybrid or electric vehicle high-voltage work.
- Electrical diagnosis is time. We charge for finding the fault, because finding it is the job, and the part is often the cheap part. We will tell you what we think it will take before we start.
Before you call, have this handy
None of it is required. It just gets you a real answer on the first call instead of the second.
Everything that is not working, not just the main one
Even things that seem unconnected. The overlap is what points at a shared ground or a shared fuse, and it can turn a long diagnosis into a short one.
When it happens, and what makes it happen
Cold, wet, bumps, after a wash, only when the engine is running. An intermittent fault with a trigger is much easier than one without.
Any accessory that has ever been fitted
A stereo, a trailer harness, a dash cam, an alarm, a light bar, whether by you or by a previous owner. Aftermarket wiring is behind a large share of electrical faults and knowing it is there saves hours.
Questions
Questions we get asked
Why does electrical diagnosis cost so much when the part is cheap?
Because finding it is the work. A five dollar connector can take two hours to locate and ten minutes to fix, and any shop that pretends otherwise is either guessing or charging you for parts until it stops. We will tell you what we expect it to take before we begin.
Can you find a drain that kills my battery?
Yes, and it is a good example of shop work: measure the draw, then isolate it circuit by circuit. It needs the vehicle for a stretch rather than for an appointment slot, so plan on leaving it.
Will you program a new key or fob?
Key fobs and keyless entry, yes. Deeper module programming that needs the manufacturer's own software is a dealer job and we will say so up front.
My problem is the RV's 12 volt system, not the truck. Same thing?
Related but a different page. The house side of a coach, its 12V and 120V distribution, converter and inverter, is on the house systems page. Same building either way.
Something aftermarket was fitted and now nothing works right. Will you touch it?
Yes, and it is common. Tell us what was fitted and roughly when. We would much rather know than find a spliced tap behind the dash an hour in.
Talk to someone who works on these
Call the shop and we will tell you the soonest realistic date rather than book you and hold your rig. Mon-Fri 8:00 - 5:00, Saturday 8:00 - 12:00.