Sometimes drivers experience a vehicle problem that they have never encountered before, and it raises questions. For example, the turn signal in a vehicle that only blinks rapidly on one side and not the other.
The fast-blinking turn signal is relatively common, but the actual problem can be confusing. It can indicate many problems. Read below to figure out what causes this and how to address it.
What is a turn signal light?
Your car has turn signal lights on all four corners. Turn signals on the external side of your car may be yellow or amber, while internally they usually appear to be green arrows, which are pointing to the direction they are supposed to turn.
Typically, your turn signal is controlled by a lever that is to the left of your steering wheel. If you move the lever up, it indicates a right turn, and if you move it down, it indicates a left turn. Your turn signal should cancel after turning or making a lane change; however, if it does not, you should cancel it manually as soon as possible.
When to use turn signals
Use a turn signal or hand signals anytime you are:
- Anytime you are turning or changing direction
- When you are pulling up next to the curb.
- Before you pull out from a stationary position next to the curb.
- When changing lanes.
- When slowing down or stopping.
- When executing a U-turn or a 3-point turn.
- When entering the traffic right-of-way.
Remember that signaling does not guarantee the right-of-way over another road user. Always ensure that the lane you intend to enter is free of traffic. Make sure to check your mirrors and be careful not to move into your blind spot to avoid a hazardous situation.
How Long Should You Signal?
You should always signal long enough to provide adequate warning to other road users.
How Long do I Signal? It depends!
- Signal a minimum of 100 feet before making a left or right turn
- Signal 5 seconds before changing lanes on the freeway or highway
Although early signaling is ideal in the majority of cases, it may involve something of a hazard when there is more than one option to turn.
For example, signaling before an intersection to indicate a turn just after the intersection may mislead another driver to interpret that a turn is happening in the intersection – they can pull out in front of you in error and cause a crash!
ALWAYS use your turn signals, no matter if you think you’re by yourself! The vehicle you can’t see is the most dangerous! And after a turn, always check to see if your indicator canceled.
How Do Turn Signals Work?
To understand the origin of a rapidly flashing turn signal, you must first understand that the basic operation of turn signals is relatively simple. A vehicle’s turn signal circuit receives power from a fused hot wire, which usually comes from the under-hood junction box.
This hot wire provides power to a flasher module, which is connected to the turn signal switch located on the vehicle’s steering column.
When a driver moves the turn signal switch either up or down, this completes the circuit and sends power to both the front and rear turn signal lights for the selected side of the vehicle.
Instead of providing a continuous flow of power to these bulbs, power is cut off intermittently as it flows to one of the turn signal bulbs through the circuit’s flasher module. There is a heat-sensitive contact in the flasher module that works with a current of power, causing the contact to expand and/or contract, making and breaking the connection.
The flasher module operates through resistance, which is affected on the circuit as the power goes to a filament of a turn signal bulb.
When there is a break in a filament of a turn signal bulb, the resistance is reduced to a lower resistance when the filament is not whole, which causes the flasher module to react by speeding up, sending the flashing signal to the other bulbs remaining in that turn signal circuit.
Common Causes of a Fast-blinking Turn Signal
Although diagnosing a fast-blinking turn signal bulb is relatively simple, thoroughness is important. This condition can be caused by one of multiple causes.
Here are some of the most common causes of a fast-blinking turn signal.
- Bad turn signal bulb
- Improper bulb in the turn signal
- Damaged flasher module
- Damaged turn signal wiring or socket
- Hyper flash due to the recent upgrade of LED bulbs
How to Fix a Turn Signal That’s Blinking Fast
To fix a fast-blinking turn signal, you must determine why it’s blinking fast.
If you follow the steps listed below, you will be able to quickly diagnose your vehicle’s lighting issue and fix what is broken.
#1. Check Turn Signal Functionality.
When evaluating a turn signal problem, check all of the lights around the entire vehicle. After you toggle the turn signal switch in a specific direction, you should verify that the front and rear turn signal bulbs on that side are working properly.
Next, toggle the turn signal switch in the opposite direction to check the other side.
#2. Check Power/Ground To The Inoperable Bulbs.
If you find that any of your turn signal bulbs are not working, you want to confirm that power and ground are present at the correct plug. You can do this by taking the bulb out and probing the pins of the receptacle with a test light.
With the clamped end of the test light grounded, one pin of the receptacle should be hot, turning the test light on. The same for the other receptacle pin once the ground is connected to a 12-volt power source.
#3. Replace Any Bad Bulbs.
If you have found an inoperable turn signal bulb in step 1, and have verified power and ground, you will need to install a new bulb.
When the new bulb is installed, check to make sure the bulb lights up and flashes properly. In most cases, this will restore flashing for every turn signal bulb to the normal speed.
#4. Replace the Flasher Relay (If needed).
If your vehicle uses standard non-LED bulbs, and you replace the bulb, but still are experiencing rapid turn signal flashing, the turn signal relay may be suspect. You can find this module at almost any auto parts store, and typically for a good price.
The relay replacement is usually as simple as replacing a fuse. It is important to check factory-specific service literature to determine the location of the module.
#5. Fix Resistance Related Issues.
If you have recently changed your non-LED bulbs to replacement LED turn signal bulbs, you have probably encountered resistance issues.
As the flasher module relies on resistance in the circuit to operate correctly, if you replace it with low-resistance LED bulbs, the flasher will cycle fast, as if a bulb’s filament is open.
To fix this condition, you can purchase and install specialty inline resistors, which will return your flasher module to its typical operating behavior.
How to Fix a Fast-Blinking Turn Signal
If your turn signal flashes too rapidly (also called a “fast blinking turn signal”), you need to find and correct the source of the problem. A turn signal that blinks rapidly typically signals that one of the turn signal bulbs is out or that there is an issue with the electrical circuit. Here’s what you can do:
- Check and Replace bulbs: Check the bulbs on the side that is blinking rapidly. Replace any bulbs that obviously are not working or that are dimmer than usual. After replacing the bulb that was out, the turn signal should blink normally again.
- Check the bulb sockets: If the bulbs are fine, check the bulb sockets for corrosion or damage to the socket. Corrosion or damage can adversely affect the connection and cause rapid blinking of the turn signal. Clean or repair the bulb sockets as necessary.
- Check for LED issue: If your vehicle has LED turn signals, or has changed the bulb to an LED bulb, rapid blinking could occur because LEDs have a lower resistance. In this circumstance, you will want to add load resistors to balance the circuit or change the flasher relay to be LED compatible to resolve the blink rate issue.
- Check for turn signal relay: If the bulbs and bulb sockets are okay, the issue may be with the turn signal relay or flasher unit. Locate the relay (usually in the fuse box) and remove and replace it, if necessary.
- Check for Wiring issues: If the above maintenance items still do not correct the problem, you will need to check for a wiring issue. Check the wiring for damage, wear, and any loose connections and make repairs as necessary.
Is Fast Blinking Illegal?
Whether or not a fast blinker is illegal is mostly subjective. The Department of Transportation does specify that, “The rate of a vehicle’s turn signal should not exceed 120 blinks a minute.” But it is possible that state laws have a lower acceptable maximum threshold.
Because of this reason, it can be hard to judge whether a fast blinking turn signal is illegal, because it is ultimately determined by the speed of the blinking as it occurs, and the laws of the state you are traveling in.
At a minimum, hyper flashing fast would expose the vehicle to increased attention from law enforcement. The light emitted from a fast blinking amber is a distracting experience and may trigger a police officer to issue a citation to a compacting motorist.