Diagnosing Turn Signal Problems

If you have owned vehicles before, you will have most likely encountered issues with your turn signal at some point or another. Fortunately, turn signals are probably one of the simplest electronic components on your vehicle to troubleshoot.

This is because turn signals are pretty simple, if fickle, car parts. They are either on or off, making troubleshooting significantly more straightforward. There are no gray areas, they either work, or they don’t, there is no ambiguity.

Diagnosing an issue with turn signals is not rocket science. When your turn signals decide to stop working correctly, they will usually display one of three symptoms.

• Rapid blinking that’s much faster than usual.
• Lighting up but not blinking at all.
• Turn signal stays on doesn’t blink

When one of these three apply it narrows down the cause to two possible chief culprits: a faulty turn signal relay or a burnt-out turn signal bulb.

Let’s look at rapid flashing first. If the turn signal is going crazy fast, that means you have a bulb out somewhere on that side of the vehicle.

Turn Signal Not Working but Bulb is Good?

If, however, the turn signal doesn’t flash at all or doesn’t illuminate, this points to a bad turn signal relay that needs to be replaced. Thankfully, replacing a turn signal relay is not a biggie. It’s easy to swap in a new relay, and they are usually relatively inexpensive.

But first, a heads-up. Depending on your vehicle, it may use one relay for flashing the turn signals and another to activate the hazard lights. Be careful to check out both if fitted when troubleshooting your turn signals. You really do not want to be without hazard lights as they are an essential safety feature to warn other road users.

Changing The Turn Signal Relay

When you have established beyond doubt that it is the turn signal relay at fault, you can relax. Swapping a dud relay for a new one is probably the most straightforward repair job you will ever have to do on your vehicle.

Here’s how:

• Check the owner’s manual for the location of the turn signal relay. Usually, they are situated on the underside of the dash in the footwell. But not always.
• If you have no luck with the owner’s manual, you will need to consult a service manual for your vehicle. You can sometimes find these in the local library.
• Once you have found the turn signal relay’s hiding place, pull out the faulty relay and pop in the new one. You can’t replace it upside down as usually there’s only one way it will fit. But take note of the alignment of any markings on the original before you pull it.
• You’re done. Check your turn signals work, and you are roadworthy again.

More troubleshooting

However, if you have changed the relay, checked all your turn signal bulbs are working, and you are still without turn signals, then you will need to up your auto-electrics game a little more. Tracking down the fault, which may be a bad ground or a loose wire, is time-consuming and frustrating. But try the following:

Examine The Connections

To change a bulb, you have to access the rear of the turn signal housing. All the plugs that feed your lights and turn signals are located here. Try one at a time, unplugging and plugging them back in. Sometimes this is enough to resolve an issue. Even a loose plug not associated with the turn signals can be the root of the problem.

Check For Bad Grounds

If your turn signal doesn’t flash or illuminate, a bad ground can often be to blame. Typically, the ground wires are alternatively black or brown. No matter, you will want to follow the ground wire to where it is bolted or screwed onto the chassis. When you locate this termination point, remove the connection, and clean up everything with steel wool before reattaching the connector.

Check The Fuse Box

As weird as it sounds, check all the fuses, not just the one related to the turn signals. Examine all the fuses and check for corrosion that may be causing a faulty circuit. Turn signals are notoriously temperamental and can fail even when the problem does not appear to be directly related. A good clean fuse box is always a good idea when it comes to the integrity of auto-electrics. It is well worth spending the time, especially if you have an older car. Just pull the fuses one at a time with the ignition off.