Service

Electrical System Repair

Battery, alternator, starter, wiring, and parasitic drain diagnosis — we find and fix electrical gremlins.

Electrical faults are where guesswork gets expensive. A car that will not start can be a battery, a starter, an alternator that has not been charging for weeks, a corroded ground, a parasitic draw, or a security system fault — and replacing parts in that order until it works is an expensive way to find out.

We test electrical systems properly at All Motors Center, with the meters and scopes to prove where the fault is before anything gets replaced.

Starting and charging

Spokane winters are hard on batteries. Cold reduces the chemical capacity of a battery at exactly the moment the engine needs more current to turn over, which is why so many batteries fail on the first genuinely cold morning of the year. Diesels are harder still, often running two batteries because the cranking demand is so much higher.

We load test the battery rather than just reading its voltage — a battery can show 12.6 volts sitting still and collapse completely under load. We test alternator output and ripple, which catches a failing diode that reads as adequate voltage but is quietly cooking the battery. We check starter draw, and we clean and test grounds and cable ends, because corroded connections cause a large share of the faults that get blamed on components.

Symptoms: slow cranking, a single click or rapid clicking, dash lights dimming when you turn the key, a battery light, headlights that brighten and dim with engine speed, or a vehicle that needs a jump after sitting a couple of days.

Parasitic draw

A battery that is flat every few days when the vehicle sits is usually a parasitic draw — something staying awake after the car should have gone to sleep. Common causes are a glovebox or trunk light that never switches off, an aftermarket accessory or stereo installed without a switched supply, a failing door lock actuator or module that will not shut down, and corrosion in a connector.

Finding it means measuring the current draw after the modules have gone to sleep, then pulling fuses methodically to isolate the circuit. It takes patience, and it is far cheaper than another battery.

Lighting and wiring

We repair headlight and taillight faults, trailer wiring and connectors, aftermarket accessory wiring, and the corroded grounds and chafed harnesses that cause intermittent faults which come and go with bumps or weather. Winter road brine is corrosive and finds its way into connectors, particularly at the rear of the vehicle and on trailer plugs.

We wire trailer connections, auxiliary lighting, block heaters and accessories properly — fused, on the correct gauge cable, and on a switched supply where it should be, so it does not become the parasitic draw we get called about next year.

Modules, sensors and networks

Modern vehicles run multiple control modules communicating over a data network. A single failed module or a break in the network can produce a dashboard full of warning lights that look like a catastrophe and are actually one fault. We scan every module, check for communication faults, and test the network rather than guessing from the symptom.

Call (509) 655-7715 and tell us what the vehicle is doing.

What You Get

  • Battery load testing and replacement
  • Alternator output and ripple testing
  • Starter draw testing
  • Parasitic draw diagnosis
  • Corroded ground and cable repair
  • Trailer, accessory and block heater wiring
  • Module and data network fault diagnosis
  • Intermittent and weather-related fault finding

How It Works

  1. 1Confirm the symptom and when it happens
  2. 2Load test the battery and measure charging output under load
  3. 3Test starter draw and check every main ground and cable end
  4. 4Measure parasitic draw with modules asleep where relevant
  5. 5Scan all modules for stored and communication faults
  6. 6Explain the finding and give a written estimate
  7. 7Repair, then retest the full circuit to confirm

Frequently Asked

Is it my battery, alternator or starter?

They produce overlapping symptoms, which is why testing beats guessing. We load test the battery, measure alternator output and ripple, and check starter draw. A battery can read 12.6 volts at rest and still collapse under load, so a voltage reading alone proves very little.

Why do batteries fail in winter here?

Cold reduces a battery's available capacity at exactly the moment the engine needs more current to crank. That is why so many fail on the first genuinely cold morning. Diesels are harder still and often run two batteries because cranking demand is so much higher.

My battery goes flat when the car sits for a few days. Why?

Usually a parasitic draw — something staying powered after the vehicle should have gone to sleep. Common causes are a light that never switches off, an aftermarket accessory wired to a constant supply, or a module that will not shut down. We measure the draw and isolate the circuit rather than fitting another battery.

Can you fix wiring rather than replace the harness?

In most cases yes. Corroded grounds, chafed sections and failed connectors are repairable, and that is usually where these faults actually live. Winter road brine is corrosive and gets into connectors, especially at the rear of a vehicle and on trailer plugs.

My dashboard lit up with several warning lights at once. Is that serious?

Often it is a single fault rather than several. Modern vehicles run multiple modules on a data network, and one failed module or a break in the network can trigger warnings across the whole dashboard. We scan every module and test the network to find the one cause.

Can you wire a trailer plug or a block heater?

Yes — trailer connectors, auxiliary lighting, block heaters and accessories, fused and on the correct gauge cable, on a switched supply where it belongs so it does not turn into a parasitic draw later.

Other car and light-truck work we do

We cover the greater Spokane area and North Idaho — see the areas we serve.