Electrical Gremlins: When to Give Up on an Old Car

Most electrical faults are annoying. Some are dangerous. If you notice any of these, park somewhere safe, shut the car off and get a mechanic’s opinion before driving it again.

• A burning plastic smell, smoke or hot wires.
• Fuses that blow over and over. Do not fit a larger fuse to stop it. That can start a fire.
• Brake or airbag warning lights.
• Stalling while driving, or power steering or lights cutting out.
• A battery that is swollen or smells of rotten eggs.

If there is smoke, get out and away from the car and call 911.

A mechanic can check these fast. Ask about each one before you agree to deep testing, since one weak part can make several others misbehave.

Diagnosis of an intermittent fault can take a long time, and it is usually billed for time spent. Before you hand over the keys:

1. Write down the pattern

   What fails, when, how often, in what weather? Does it happen after rain or on bumps? Take videos of the dash. It helps a lot when the fault hides at the shop.

2. Agree on a limit

   Ask the shop to stop and call you at a set amount of time, before going any further. Get that on the work order.

3. Ask for findings each time

   What did you test, what did you rule out, and what is next? You paid for that information, even if the car is not fixed yet.

4. Check for a specialist

   Some shops focus on automotive electrical work. For a tough fault, that may save time compared with a general shop.

• Is this one fault, or do I have several problems?
• Could water have gotten in? Where?
• Is any wiring chewed, cracked or corroded? Could you show me a photo?
• Is this an electronic control module, and can you still get one for this car? Does a replacement need programming?
• Do you think the repair you recommend will cure the symptom, or is it the next thing to try?
• Is this car safe to drive in the meantime?

Stay with the car when the shop finds a clear cause: a bad alternator, a corroded ground, a specific chewed wire or a failed window motor. These are normal repairs, even on old cars. If the rest of the car is sound, there is no reason to give up over a fault that has a clear fix.

It may also be fine to live with a small fault that affects comfort only, like a dead rear window or a broken dome light, as long as it does not touch safety. Not everything has to be fixed.

• Several systems keep failing, one after another, and each repair only moves the problem somewhere else.
• Water or corrosion has reached the wiring. After a leak or a flood, corrosion can continue to spread.
• Modules are unavailable for your model, or the only choice is a used one with no assurance it will work.
• You have spent your agreed limit twice, and nobody can reproduce the problem.
• The car stalls or loses safety features, and no one can tell you why. You can no longer trust it, and you should not keep driving it.

Before deciding, check what the car is worth and our list of signs it is time to stop repairing.

A private buyer may be fine with a known quirk, as long as you tell them what it does and what you have tried. Never try to hide a warning light. If it no longer starts or you do not trust it, we buy non-running cars and tow them free. Just make sure we can get into it, and tell us if the electrical problem has left the car stuck in park or locked, since that can affect loading. See what to do if you have no keys.