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Why Is My Left Blinker Stuck on and How Can I Fix It?

By: Author Kris Peter

Posted on

Categories Maintenance

The blinkers are among the safety features of any vehicle because they help alert other drivers of your intention to change lanes or take left or right turns. As such, we all hope we don’t get to the point when we need to ask, “Why is my left blinker stuck on?” That said, you must know the answer to this question, whether or not you’re currently facing the said problem.

So, why is my left blinker stuck on? The most common reasons your left blinker remains blinking or won’t turn off are issues with your vehicle’s left-turn signal’s electrical system and the turn signal system itself. Each of these problems also has a root cause or causes that you need to note.

Let’s go into the specifics and talk about the root causes of each of the general reasons you’re having trouble turning off your left blinker. I will also share how you can diagnose and resolve these problems.

Why Is My Left Blinker Stuck On?

Car Dashboard Left Turn Signal Blinker

Electrical System Issues

We all know that our vehicle’s lighting system, including the blinkers, will require a good supply of electricity to function. So, surely you won’t be surprised to hear that your left blinker would stay blinking or on when there are electrical system issues. Specifically, you need to look for problems in your left blinker’s wiring system, bulb, bulb socket, and fuse.

  • Faulty Bulb or Socket

Your left blinker would remain blinking or turned on because of a burnt turn-signal bulb. It may also be due to a damaged bulb socket that could lead to circuit malfunctions.

  • Wiring System Problems

Your vehicle’s left blinker won’t receive enough power it needs when the parts connecting its battery to the left blinker are loose or corroded.

The same goes for when there are short circuits or frayed wires. These issues could disrupt the flow of electricity, leading to the prolonged activation of your left blinker.

Although a blown fuse will most likely cause problems with both the right and left blinkers, it’s worth noting that there are incidents when only the left or the right stays on.

Turn Signal System Issues

The turn signal comprises multiple parts, from the visible lever to the hidden wires and springs. When your left turn signal (or only one of the turn signals) starts acting up, here are some issues to consider:

  • Faulty Turn-Signal or Flasher Relay

When you ask, “Why is my left blinker stuck on?” a common answer you would hear from DIYers and professionals is a damaged, worn, or torn flasher relay. Most especially when your blinker stays on even when you turn off your vehicle’s engine or turn signal switch is in its neutral position.

  • Faulty Turn Signal Switch

This switch is responsible for turning your vehicle’s signal bulbs on and off. It would malfunction or become faulty for two main reasons.

One is the presence of corrosion or moisture in its housing. After all, these elements could interfere with your left blinker’s proper operation.

Another is problems with the turn signal switch assembly or the connections between the plastic piece inside and the clockspring or canceling cam. These connections might be loose, broken, or worn out.

  • Faulty Turn Signal Module

If you have a young or newer passenger car, truck, or SUV model, its turn signal system most likely has high-grade, modern functions like full flash and canceling modes. If it does, it means it also has a turn-signal module.

Typically, this system goes into sleep mode a few minutes after you turn off your vehicle’s engine to conserve battery power. However, your turn signal will continue drawing power from the battery when the module malfunctions or goes bad. In this situation, the turn signal you switched on will remain on for as long as it’s supplied with power.

How to Fix Left Blinker That Stays On or Blinking

To check and fix any of the issues with your left blinker I mentioned above, follow these recommended steps:

Step 1: Check and Fix the Left Blinker Bulb Issues

You can access the blinker bulb via your vehicle’s engine compartment for the front bulb and trunk for the rear bulb or by removing the lens. In some vehicle models, you might need to access the said bulbs through the instrument panel. I advise you to check your owner’s manual to avoid guessing.

Generally, vehicle bulbs are usually two-filament models. Check each filament to ensure they’re both in good condition and the bulb glass is darkened. If you find any issues, replace the bulb with a new one of the same wattage and type or universal-fit LED turn signal or blinker bulbs (view on Amazon).

Step 2: Check and Fix the Left Blinker Bulb Socket Issues

Once you remove the turn signal bulbs, inspect the sockets for any sign of moisture or corrosion. If present, simply dry and clean them using a clean, soft microfiber cloth or a soft-bristled brush. For any damages, replace the problematic socket.

Step 3: Check and Fix Left-Turn Signal Issues

Now, visually check your turn signal’s housing and lever for any sign of corrosion or moisture. If there are any, simply wipe them dry and clean with a soft microfiber cloth and a soft-bristle brush. Apply a small amount of dielectric grease to avoid future corrosion.

Next, you need to check if the turn signal switch has a broken clockspring, assembly, or canceling cam. Here’s what you need to do:

  1. Disconnect your vehicle battery’s negative cable from the battery.
  2. Carefully remove the plastic casing’s top and bottom you’ll find around your vehicle’s steering wheel.
  3. Loosen the plastic casing bolts and then dislodge any trim clips you’ll find.
  4. Gently pry off the plastic clips holding the turn signal switch using a small screwdriver or the screwdriver in your handy, durable multi-tool (view on Amazon).
  5. Disconnect the switch assembly’s wires.
  6. Check the switch or assembly for any damage.

If any part is broken, worn, or damaged, replace the turn signal by following these steps:

  1. Grab your new switch assembly and reconnect the wires you disconnected earlier.
  2. Lock your vehicle’s new switch assembly into where you removed the old one.
  3. Carefully push it down until it is secured into its place.
  4. Re-install the plastic clips with the help of your screwdriver.
  5. Re-install and tighten the plastic casing bolts, followed by the trim clips.
  6. Re-install the plastic casing around your vehicle’s steering wheel.
  7. Reconnect the negative cable to your vehicle’s battery.

That’s it! It’s time to check if your turn signal is working properly.

Step 4: Inspect and Fix Wiring System Issues

Like with the left blinker bulbs, where you can access the wiring harnesses or connectors will depend on your vehicle’s model. Hence, again, you need to refer to your owner’s manual. Not only that, but you also need the manual for proper wire identification.

In this diagnostic and repair step, you will need a test light.

Now, the first thing you need to do is to find your vehicle’s left turn signal wiring diagram in the manual. Take note of the color designations and electrical connector terminal number.

Next, access your vehicle’s left turn signal’s electrical connector, then look for the wires you identified earlier. Turn your ignition key on, ensuring you don’t start the engine.

Locate the wire in your switch connector responsible for supplying power to the left turn signal switch. Check for any loose connections that you need to tighten. Also, check for any wear or damage to the wiring harnesses. If there are, you will need to have a professional replace the wire for you.

After inspecting the connections and wires, connect your test light to a ground under your vehicle’s dashboard, such as a bolt or unpainted metal bracket. Then, operate your vehicle’s left-turn signal switch and back probe the wire supplying power to the said switch.

Your test light should illuminate or flash. If not, it means you have a bad or malfunctioning flasher unit and/or a short circuit or an open circuit between your battery and switch.

If this is the case, it’s best to bring your vehicle to a professional for further diagnostic tests. They’re also the best to fix flasher relay and circuit issues.

Then, back probe the connector’s wire responsible for supplying power to your vehicle’s left-turn signal lights. At this point, your test light should illuminate. If it doesn’t, it means your left-turn signal has a problematic wiring system. As such, you will need a professional to replace it.

Step 5: Inspect and Fix Fuse Issues

Similar to the left-turn signal wiring system, where the fuse is located will depend on your specific vehicle model. Thus, again, make sure to check your owner’s manual.

Once you locate the fuse box corresponding to the turn signal, check if it’s blown out or damaged. If it is, it’s best to contact a professional mechanic because it’s most likely that there are other underlying issues. It’s also safer for the fuse to be replaced professionally.

A Table of Summary of the Causes and Solutions

Now, let’s deduce the information I provided above so you have a quick reference when faced with the issue. Here’s a table summing up the reasons why your left blinker gets stuck or stays on, together with the corresponding solutions:

General CausesSpecific CausesSolutions
Electrical System IssuesFaulty Bulb or socketBurn out bulbReplace
Moist or corroded socketClean
Damaged socketReplace
Wiring System IssuesLoose connectorsSecure or tighten
Corroded connectorsClean
Short circuit or frayed wiresBring to a professional
Blown FuseBring to a professional
Faulty Turn Signal SwitchCorrosion or moistureClean and apply dielectric grease
Loose assembly connectionRe-assemble
Damaged or broken assemblyBring to a professional
Faulty Flasher RelayWorn, torn, or damaged flasher relayBring to a professional

Understanding Why Your Left Blinker Stays On or Blinking

As you have learned by now, there are two major systems in your vehicle you need to inspect when your left blinker starts acting out. One is the electrical system providing power to the signal light. Another is the turn signal system parts.

You can diagnose and resolve most of the issues on your own. But like with issues with car oil leaks, push-button start, and other vehicle parts, some of them require a professional’s experienced and skilled eyes and hands.

As such, I also highly recommend that you have a professional check your vehicle even when you have resolved the issue. This way, you’re assured that you haven’t missed anything and any underlying problems get fixed before they worsen and cause more serious problems.

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