Toyota Corolla Miles-to-Empty Display: Instructions and Common Problems

The miles-to-empty feature can save you a lot of hassle from your car running out of fuel on roads or intersections with high traffic. It can also help prepare you before embarking on a journey to the middle of nowhere, where you are unlikely to access a gas station. This article will cover instructions on using the miles to display and common problems associated with the feature.

Dashboard software problems highlights

• Howcommon:notreallycommon
• Mainreasons:voltage anomalies, software glitch, initially wrong software
• DIY diagnosis:impossible
• DIYrepair:impossible
• Solutions:if settingsdon'thelp, have software updated in dealership
• Can you drive?yes
• Price in dealership:$200 - $450

Instructions for Using Miles to Empty Display

Miles to empty is also known as distance to empty. It's a feature you'll easily access on the car's dashboard. You can use it to estimate the miles or distance you can cover before running out of fuel. When the fuel level in the gas tank starts running low, the vehicle sends a warning on the dashboard.

This warning comes as a low-level fuel symbol accompanied by a chime. The "distance to empty" (DTE) message signal will then appear. In this instance, the miles-to-empty feature in your Toyota Corolla comes in handy to alert you how far you'll likely drive with the remaining fuel. 

The distance to empty estimates may vary depending on a variety of factors. The factors include:

• The driving style of the driver. Driving on a highway will have different miles to empty to city driving. This is because you can move at a constant speed on a highway. On the other hand, city driving requires frequent changes in speeds and stopping. This leads to lower gas mileage than highway driving due to burning more oil and fuel. As a result, miles to empty will show a lesser distance in city driving than in highway driving.
• Carrying heavy loads, idling, or towing a trailer for an extended period can also result in miles to empty indicating a lesser distance than when the vehicle has no load.
• The type of road surface also affects miles to empty. Driving the vehicle through rough terrain will lower miles to empty than moving on a smooth one. That's because the car consumes more fuel on uneven terrain.

It would be best to use miles to empty as a guide to help with decisions like when to refuel your Toyota Corolla rather than a correct figure of the distance remaining for fuel to run out. 

How Does the Toyota Corolla Calculate Miles to Empty?

The car's Electronic Control Module (ECM) processor periodically records the distance covered and the fuel amount remaining in the gas tank. It does this with the help of the fuel level sensor that takes the readings of fuel left in the tank. The processor then uses the distance covered and the amount of fuel left readings to calculate the mileage. It uses the formula (distance/ fuel consumed) to get the average miles per gallon. 

The value of the distance to empty is a product of the average miles per gallon and the gallons of fuel in the tank. An example is if the average miles per gallon is 15, and the car has 10 gallons of fuel remaining in the tank, then the distance to empty will be 150 miles.

The ECU arrives at the value by multiplying 15 and 10. The distance to empty value resets itself after refilling the fuel tank. Taking the miles to empty with a grain of salt is always advisable since it's inaccurate and may vary based on many factors.

When the distance to empty reaches zero, the refuel message and the low-level warning light illuminate the dashboard. However, there's usually about 2 gallons of fuel left. That means the car can drive for another 30-60 miles before it entirely runs out of power. This safety precaution allows the vehicle to get to the nearest fuel station. It's advisable to refuel your Toyota Corolla once the miles to empty become low or get to zero and not wait for it to run out of fuel.

This is because frequently operating your car on an almost empty fuel tank has adverse effects such as:

• Overexertion of the engine.
• Additional stress on the car's fuel pump causes it to wear out.
• The engine can stall due to less delivery of power to the engine.
• Formation of muck or sludge in the fuel tank.

What are the Common Miles to Empty Problems and Reasons for Those Problems in Toyota Corolla?

Some common problems you may experience on the Toyota Corolla's Miles to Empty display are:

• Fluctuating readings such as sudden jumps or drops in miles to empty value.
• Inaccurate readings
• Erratic miles to empty behavior.

Some of the common causes for those problems are:

1) A Faulty Fuel Level Sensor

The fuel level sensor is also called the fuel gauge. It plays the role of monitoring the level of fuel available in the fuel tank. This helps inform the driver when the fuel level is low to enable refueling. The fuel level sensor comprises the indicator and the sensing system. A needle-also called a gauge- is connected to the instrument panel and shows the fuel level. 

The sensing system, known as the sending unit, is divided into a variable resistor, float switch, and wiper. The fuel level drops as the vehicle continues consuming fuel, making the float drop. When the float drops, the wiper can move across the variable resistor. This leads to a voltage change. As the fuel becomes empty, the resistance increases.

The voltage difference and current causes the indicator to move, showing empty on the dashboard. A defective sending unit can make the fuel level sensor not function correctly. This, in turn, will affect the fuel reading and, eventually, the distance to empty value. 

During the vehicle's movement, the sending unit moves consistently and rubs the variable resistor. This constant motion can cause its contacts to wear out and cause an open circuit. The sending unit will then relay a wrong voltage feedback, affecting the fuel gauge and distance to empty readings on the dashboard. 

2) A Defective Instrument Cluster 

A defective instrument cluster is another possible cause of inaccurate distance to empty readings. The instrument cluster consists of several displays, including the fuel gauge, odometer, and the distance to empty display. Modern instrument clusters consist of a fully integrated circuit. This means all gauges and indicators on the instrument cluster will likely misbehave whenever it has a problem. Common problems that may cause the instrument cluster to fail are:

• Excessive vibrations and heat.
• Spilling of liquids such as drinks, which may short-circuit the system.
• Poor connections of cables and wires or blown fuse.
• Design flaws.
• A battery drain or old and weak battery.

When the instrument cluster malfunctions, it may become dim, fail to turn on, lose backlighting, give false readings, or fail to communicate with the rest of the car. 

3) Engine Control Unit Failure

The ECU constantly monitors the control modules and sensors, interprets the data, and transmits the information to the instrument panel. It does this using VAN or CAN bus communication networks.

The ECU decodes and converts the data it receives and presents it to the instrument cluster through indicators, signs, and messages that the driver can understand. Failure of the ECU can cause it to relay the wrong information to the instrument cluster. The data can be the miles to empty readings displayed in the instrument cluster. This may mislead the driver to make a wrong decision.

Some causes of ECU failure are:

• Corrosion by water and excessive vibration.
• Corrupt data.
• Failed sensors.
• Faulty electrical wiring may short-circuit it.

4) A Circuit Malfunction

A circuit malfunction is another possible reason your Toyota Corolla displays incorrect miles to empty. A circuit issue causes an inaccurate reading since it can tamper with the fuel level sensor, which sends the fuel level data required to calculate the distance to empty values.

This means that the fuel gauge will also display a wrong reading. A faulty electrical circuit may also prevent the ECU from getting the correct vehicle speed from the speed sensors or how much fuel it instructs the fuel injectors to deliver.

This data helps the ECU to come up with a miles-to-empty reading. Corrosions or loose connections are reasons the electrical circuit may malfunction, affecting miles to empty. 

How to Fix Inaccurate Miles to Empty Readings in Toyota Corolla?

To find the correct solution to inaccurate miles to empty readings, you'll have to first find the source of the problem through a proper diagnosis. Here are some solutions based on the possible causes of inaccurate miles to empty readings.

A diagnostic trouble code (DTC) like P0463 signifies an issue with the fuel level sensor. To further diagnose whether the sensor is faulty, visually inspect the grounding strap for any signs of rust or corrosion. You can also use a voltmeter to test the voltage across the grounding circuit. Verify the voltage you get by comparing it to the correct voltage that the circuit needs to have. If you find the fuel level sensor is faulty, replace it to restore its functionality. 

Before you replace the instrument cluster, it's advisable to check which part of the panel could be faulty. Modern instrument clusters have a self-test feature that you can activate using a diagnostic tool.

It tests all the gauges, displays, and lights to determine which hardware component isn't functional. If the gauges read incorrectly, you can use a diagnostic scanner tool to check the incoming live data. If the values on the device match those on the instrument cluster, the issue is most likely the components that are sending the data.

This could be the ECU or sensors. However, if the values on the cluster are different from those on the diagnostic tool, then the issue lies with the instrument cluster. A faulty instrument panel needs replacing. 

A defective ECU needs resetting if it goes bad due to a factor such as corrupt data. If the ECU is damaged due to contact with water or excessive vibration, it'll require replacement with a new one. 

To diagnose a circuit malfunction, you'll need a tool such as a multimeter to inspect the circuit that supplies power to the instrument cluster panel. You can also visually check for frayed wires or loose connections. You'll then need to fix the open connections and replace the damaged wires with ones in good condition.

Bottom Line

There you have it-instructions and common problems of the miles-to-empty display. Consult an expert mechanic if you require help diagnosing and solving issues related to the miles to empty display.