Selling a car with electrical problems you can't trace

Before you decide, rule out the common causes. AAA points to the battery and alternator first, and a burning smell is a sign you should not ignore.

Rule out the battery and alternator first

AAA says the most common reason a car won't start is a bad alternator or battery, so it tells drivers to check those first (AAA). They also explain plenty of faults that seem random. A failing alternator can drain the battery and cause electrical problems all over the car, and AAA lists a battery that keeps dying, even after it has been replaced, as a sign the alternator may be the problem.

You can check both with a cheap multimeter set to DC volts:

If the numbers are off, you may have found your "untraceable" fault. If they look right, keep reading.

Two more things worth a look

Ground cables. AAA says a faulty or loose ground cable can stop current from flowing properly and cause starting problems. Look where the cables bolt to the body and engine for corrosion or a loose end.

Fuses. Fuses protect the electrical system, and AAA notes a blown one can knock out vital parts such as the ignition system.

When a smell or smoke is a warning

Not every electrical fault is just a nuisance. AAA says a burning rubber or electrical smell can point to alternator trouble.

Wiring itself can be the danger. One 2026 recall shows how. On 2021 to 2026 Ford Broncos, NHTSA recall 26V468 says a short in the engine compartment wiring harness may create heat or a spark, causing smoke or setting nearby parts on fire (NHTSA recall report). That recall tells owners not to drive the vehicle and to park it outside. Owners are notified by mail and sent to a Ford or Lincoln dealer for the fix.

Two lessons carry over to any car:

• Don't shrug off a burning or electrical smell. AAA ties it to alternator trouble, and the recall shows a harness short can start a fire.
• If a recall letter came in the mail, read it before you sell or repair anything. The repair in that recall goes through the dealer.

The real problem with a fault you can't trace

A dead battery has a clear fix. An intermittent short does not. Each round of diagnosis costs money whether or not it finds the cause, and you can't know at the start how many rounds it will take. We don't quote repair prices here because we have no official figure to give you, but you can ask any shop for a written diagnostic estimate and a cap before work starts.

Set that next to what the car is worth. Our guide on repairs that cost more than the car shows how to do the comparison.

Keep it and fix it, or sell it

Fixing is the better bet when:

• the battery or alternator tests bad
• you found a loose ground or a corroded cable end
• a recall covers the fault, so the dealer does the repair
• the car is otherwise sound and worth well more than a capped diagnosis

Selling as it sits is the better bet when:

• the basic checks pass and the fault still comes and goes
• a shop has already charged you once without finding it
• you smell burning or have seen smoke and don't want to drive it again
• other big repairs are lining up behind this one

If the fault has left the car dead, see our page on selling a non-running car. If a short has already burned something, our fire-damaged car guide picks up from there.

Be upfront with a buyer

We could not confirm a rule that says what a private seller has to disclose about electrical faults, so we won't claim one exists. Writing down what you know still protects you: which lights or parts act up, when it happens, what has been tested and what the readings were. Our page on selling a car as-is covers what that term means in a sale.

After the sale

A car with a fault may sit for a while before it is fixed or scrapped, so close out your side once it is gone. Our after you sell page covers plates and insurance.

Selling it to us

We buy whole non-running and junk cars, electrical gremlins included. You can sell the whole car as it sits, and pickup is free anywhere in the US. To get an offer, describe the car (year, make, model, miles), what the fault does, and whether it starts. If you took voltage readings, include them.

Questions first? Call (877) 421-6008.