4LO / 4HI Light Flashing Toyota Tundra – Why And What To Do?

The Toyota Tundra's four-wheel-drive system can handle tough terrains, but it's not immune to problems. If the 4LO / 4HI light of your Toyota Tundra is flashing, you may wonder about the cause of the problem and how to fix it. Fortunately, we have consulted experts in this field, and here is what they have to say.

Problems like a damaged actuator, broken diff locker, defective transfer case, and bad signal can cause the 4LO / 4HI light on a Toyota Tundra to flash. The following are some things you can do to tackle the problem:

  • Check the actuator and transfer case
  • Scan the truck for any bad signals
  • Contact a mechanic

This problem can be easy or difficult to fix depending on the cause. Keep reading to get detailed information on how to deal with a blinking 4LO / 4HI light.

A toyota tundra display in snow, 4LO / 4HI Light Flashing Toyota Tundra - Why And What To Do?

Why Is My Toyota Tundra 4LO / 4HI Light Flashing?

The following are the most common reasons why the 4LO / 4HI light on a Toyota Tundra is flashing:

Damaged Actuator

The actuator is the component that enables the user to engage the four-wheel drive system. It is equipped with motors and a rotor that give the driver the ability to switch between 2WD and 4WD driving modes.

Like all of the other components of the truck, the 4WD actuator can get damaged. Salt and other types of impurities have a high likelihood of causing the ground on the 4WD actuator to corrode.

In addition, the location of the 4WD actuator relay on the underside of the vehicle makes it vulnerable to scratches and water, both of which might eventually lead to a short circuit or a signal failure in the system.

In the event that the actuator is broken, it will not respond to any commands, which may cause damage to your 4WD function or prevent your 4LO from being able to engage at all and keep the 4LO light flashing.

Broken Diff Locker

When it comes to off-roading, locking differentials are a feature that may completely transform a vehicle. They accomplish this by causing the rotation of both tires that are mounted on an axle.

If your 4LO light is blinking, it may indicate that your differential locker is damaged or that a component of the differential locker has broken. 

In the event that this happens, there will be no reaction of 4LO, and you will no longer be able to engage or disengage it. As a result of this, the four-wheel drive low-range signal on your Toyota Tundra can continue to blink.

Defective Transfer Case

The part of a Toyota Tundra or truck known as the transfer case is responsible for distributing the engine's power and torque to the vehicle's front and back axles so that it can move forward.

If something goes wrong with your transfer case, your vehicle may switch between two- and four-wheel drive on its own. This implies that the vehicle is unable to remain in drive mode, which might cause the transfer case or other systems on the vehicle to become damaged or put the driver in danger.

In addition, if the transfer case is damaged, the 4LO light will flash, and you will need to immediately replace it.

Bad Signal

It's possible that a malfunctioning signal is to blame for the flashing 4WD light on your dashboard, as well as the failure of the 4WD system to engage.

This could be because of a low voltage caused by a dying battery, a corroded electrical line, or even a defective sensor on the device. It's also possible that the problem is a blown fuse or a defective switch on the dashboard.

Wiring And Connection Problems

There is usually more than one cause behind electrical issues in a vehicle. There may be a problem with the electrical connection in your vehicle. A fuse that has blown will result in problems.

Sometimes the problem is that one component of the system continues to take power long after the engine has been turned off, and as a result, the battery is gradually depleted.

These electrical problems may manifest themselves as a continual flashing of the 4LO light on your Toyota Tundra, and might be triggered by a short circuit or a lack of continuity in the wiring.

What To Do If My Toyota Tundra 4LO / 4HI Light Start Flashing?

Toyota tundra cavalier Blue by the cabin in Hayward

When your 4LO /4HI light blinks and your engine check light is on, you should check out your truck. You can have experts diagnose and fix it, or you can do it yourself. Here are some things you can do to fix the problem:

Check The Actuator And Transfer Case

If after examination, it's not an electrical problem, the first step in resolving the 4lo flashing issue is determining the root cause of the flashing light.

Therefore, there are a number of potential issues you might investigate, such as a broken actuator, transfer case, etc. The vacuum valve assembly can also be the source of your vehicle's blinking lights.

But if the actuator and transfer case have already been tested and the engine 4lo/4hi light is still flashing, it may be a faulty signal.

Scan The Truck For Bad Signal

Scanning your Toyota Tundra codes is one way to verify the signals. The scanned codes will direct you to the source of the problem and provide instructions for fixing it.

Repairing your vehicle properly requires you to be able to read error messages. In order to diagnose and repair your vehicle's issue, you can purchase a fault code reader from a store.

Check Your Electrical Connections

Make sure there isn't a loose wire, faulty connection, blown fuse, or any other problem by checking each and every connector.

Unplugging the wire's connector at the sensor or load ends can help narrow down the source of an electrical problem. Once the source of the problem is detected, the faulty electrical wiring should be repaired.

If you are lucky, fixing the wire's casing will be all that's needed to get it working again. You may need to replace the wire altogether if the problem persists.

Contact A Mechanic

Woman contacting her car insurance for roadside assistance

If you are having trouble determining the cause of the problem and the 4LO/ 4HI light is still flashing, the best thing you can do is call a mechanic for assistance.

The expert will assist you in diagnosing and inspecting your vehicle, as well as assist you in repairing and replacing any broken components that they find.

Shold I Use 4HI Or 4LO?

If you are unsure about when to use 4HI or 4LO, you should utilize 4LO when driving through deep snow. When you are in 4LO, you should never go faster than 40 miles per hour. The 4LO will assist you in freeing yourself from a stuck position or climbing a steep incline while maintaining a slow speed.

As soon as it is secure to do so, you should switch to 2HI or 4HI. Use 4HI when you are traveling on slippery surfaces on a good road or highway, or when you are driving under the rain or on ice. 4HI should never be used at speeds lower than 15 miles per hour.

Is It Okay To Drive While 4LO / 4HI Light Is Flashing?

Even though the illumination of a warning light like 4LO / 4HI is never a good sign, it does not necessarily mean danger. However, if your vehicle has a warning light, you should avoid driving with it at all costs. 

If a warning light, such as the 4HI, flashes constantly for more than thirty seconds, it indicates that there is an issue somewhere on your drivetrain system and that the 4WD mode has not been activated.

So, it is in your best interest to pull over, inspect the automobile, and then ask for assistance from a trained specialist.

How Do You Reset 4WD Light?

To clear and reset the 4wd light in your vehicle, open the hood of the vehicle, and then locate the nut that is attached to the negative terminal in the vehicle. Unscrew the nut, and then restart the computer.

If that doesn't work, another option is to turn the ignition to the "On" position, but you shouldn't start the vehicle. Keep your foot pressed on the gas pedal for three seconds. After a countdown of ten seconds, turn off the ignition and start the engine.

Acceleration car control with pedal

Can You Switch From 4HI To 4LO While Driving?

Yes, you can shift from 4HI to 4LO while driving. However, it is advisable to bring the vehicle's speed down to 5 mph with the gas pedal released and the transmission in the neutral position.

In a nutshell, it is ideal to switch between 4HI and 4LO with the truck in a slow roll. This allows for a smoother transition.

To Wrap Up

2022 Toyota Tundra SR5 Double cab car during sunset in Fairfield

Different problems can cause your Toyota Tundra 4LO /4HI light to flash. If you notice this problem, all you have to do is inspect the actuator and transfer case and scan for a bad signal. You can contact a professional to help you fix the problem if you can't do it yourself.

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