Electrical problems scare off a lot of shops. We trace them properly, from sensors and wiring to starters, alternators, power windows and dead-battery drains.
Modern vehicles run on electricity as much as gasoline. Dozens of sensors and modules, miles of wiring and hundreds of connectors all have to work together, and many emissions problems are really electrical problems: a broken sensor wire, a corroded connector or a failed heater circuit in an oxygen sensor. Walnut Smog & Repair traces those faults to the source.
Electrical diagnosis is where a lot of money gets wasted on parts swapping. We use wiring diagrams, voltage-drop tests and the vehicle's own data to trace a fault. If your battery keeps dying, we test it and the charging system first (see battery service), then measure for a parasitic drain and isolate the circuit responsible.
Rats and other rodents chew wiring harnesses on cars parked outside or in garages near brush and trees, which is common around Pasadena and the foothills. Newer cars with soy-based wire insulation seem to be especially tempting. Symptoms can be random warning lights, a no-start or an engine that suddenly runs badly. We repair damaged harness sections properly.
A sensor circuit fault keeps the check engine light on, and that means an automatic smog failure. If you've got a code your parts store couldn't explain, start with our diagnostics.
It could be the battery, the alternator, a bad connection, or a parasitic drain from a module or light that stays on. We test to find out which.
Yes. A broken sensor wire or circuit fault sets the check engine light, which is an automatic fail.
Yes. We test the switch, motor, regulator and wiring to find the failed part.
Yes, after testing to confirm they're the cause.
Yes. We repair damaged harness sections and connectors.
Smog checks, failed smog repair, check engine diagnostics and complete auto repair on E Walnut St. Honest answers and fair prices.