How to Fix That One Super Annoying Electrical Gremlin No Mechanic Can Seem to Find

We've all been there - driving down the road when some weird electrical issue pops up seemingly out of nowhere. The check engine light comes on, the radio starts making strange noises, or the windows stop working. You take it to your mechanic, but they can't seem to pinpoint the exact problem. Finding and fixing these elusive electrical gremlins can be frustrating, but with some detective work and testing, you can track it down.

Thoroughly Check All Fuses

The first thing I do is check all the fuses. Problems like dead power windows or radio can often be caused by a blown fuse. I'll take out each fuse and visually inspect it for any breaks or damage. If needed, I'll use a multimeter to check for continuity. Replacing any blown fuses can potentially fix the problem.

I pay extra attention to fuses related to the problem area. For example, if the power windows aren't working, I'll check the windows and accessory fuses first. I'll also check the big fuses that protect major systems, like the battery and ignition fuses.

Inspect All Connectors and Wiring

Next, I'll carefully inspect wiring and connections. I look for any loose, disconnected, or corroded connectors, especially around the problem area. For example, if the power door locks are acting up, I'll check the lock actuator connectors.

I also visually inspect the length of wire for damage like chafing or exposed copper. Electrical problems often stem from damaged or deteriorated wiring. I wiggle wires while watching for intermittent problems to find breaks in the copper conductor inside the insulation.

Check for Communication Errors

For complex issues like check engine lights, I'll hook up a scan tool and look for communication errors. Problems like a shorted CAN bus wire can cause all sorts of strange behavior. Scan tools can quickly pinpoint communication issues and determine if any modules have stopped talking on the network.

I'll also check for dedicated diagnostic trouble codes that point to specific faults in communication wiring. Trouble codes like U0001-U3FFF indicate various CAN bus faults that can be traced back to wiring issues.

Perform a Voltage Drop Test

One of my go-to methods for finding electrical gremlins is the voltage drop test. This measures the quality of the electrical connection between the battery and different loads like the starter motor or a headlight.

Using a multimeter, I'll connect the positive lead at the battery power source, and connect the negative lead at the device I'm testing. I then operate the device while watching for excessive voltage drop on the meter, which indicates high resistance in the circuit. This can identify exactly which wire segment needs repair.

Check Grounds

Problems are often caused by poor ground connections, so I'll visually inspect all ground points. Grounds commonly degrade, rust, or become disconnected altogether. I ensure all ground connections are clean, tight, and corrosion-free.

I also perform resistance measurements between ground points to check for excessive resistance. High resistance to ground can cause all sorts of weird behaviors that are hard to track down.

Swap in Known Good Parts

If I still can't isolate the problem area, substituting new parts one-by-one can help zone in on the faulty component. I'll start with parts on the problem circuit that are cheap and easy to change. For example, with radio noise I may swap in a new antenna. If the problem disappears with the new part, I've found the culprit.

This divide and conquer strategy eventually isolates the shorted wire, bad module, or faulty connector causing the issue. It may take some time and money, but will get you closer to a fix.

Finding an electrical gremlin takes patience and diligence, but using these troubleshooting techniques I can eventually track it down. I don't let the problem beat me - I beat the problem!