Mitsubishi ASC Service Required Warning – System Disabled

If the Mitsubishi vehicle is displaying ASC system service required or ASC System Disabled, don’t panic. This guide will explain what common problems trigger the ASC system disabled warning.

If your Mitsubishi ASC light stays on all the time, it means there is a problem with the Automatic Stability Control (ASC) or Anti-lock Brake System (ABS).

What does ASC mean on a Mitsubishi vehicle?

Mitsubishi Active Stability Control (ASC) system combines three functions:

1. Anti-lock Brake System
2. Traction Control
3. Stability Control

ASC monitors inputs like wheel speed and brake pressure and adjusts engine power accordingly when loss of traction is detected. ASC on a Mitsubishi ensures the vehicle has sufficient traction and control in any situation. ASC helps keep you safe in slippery conditions like rain or snow. 

You know when the traction control is kicking in because the little ASC light will blink on the instrument panel. A flashing ASC light indicates an unsafe amount of wheel slip, which means you should slow down.

A faulty ABS wheel speed sensor is the most common problem that triggers the ASC light to stay on in a Mitsubishi. Other possible issues that are less likely to happen include:

• a faulty ABS pump,
• weak battery,
• blown fuse, or
• defective steering angle sensor. 

• The ASC Service Required light could mean that one of the ABS wheel speed sensors is bad. 
• If the ASC Service light is on, remember that your ABS capability could be reduced or switched off until it is repaired. 
• The wires from the ABS sensor up through the wheel hub could be corroded or broken. This is possible if you live in an area with harsh winters, given how much salt gets used on the roads. 
• The ASC Service Required light in some cars means that traction, stability, ABS, and 4WD are disabled.    

Symptoms

If there is an issue with the ASC system, the vehicle will warn the driver with an ‘ASC system service required’ warning message on the dashboard, or the ASC light stays on.

It is important to drive moderately if the ASC light stays on. When the ASC light is on, stability control is disabled, affecting handling and overall driving performance.

• ASC Service Required light comes on.
• When driving in unsafe conditions, the ASC light does not blink.
• The ABS doesn’t engage under a panic stop.
• You have a loss of traction due to the 4WD being disengaged.
• ASC System Service Required — message in the vehicle display and the ASC warning light illuminated on the dashboard.
• Noticeable wheelspin — during aggressive accelerations from standstills. This will also happen when going up steep inclines when the traction is poor.
• Loss of traction — when going through tight corners at higher speeds. Depending on driving conditions, the vehicle might either oversteer or understeer.
• The engine may not start—no cranking action after turning the key. In most cases, this will start as an occasional issue that also triggers the ASC warning message.
• An inoperable 4WD system —on vehicles equipped with permanent all-wheel-drive systems.
• Cruise control doesn’t work. — The cruise control can no longer be enabled.
• Limp mode / ASC Off — Transmission will no longer change gears. Typically will get stuck in second gear.
• Beeping for several minutes when you start to drive.
• 4WD light flashing on and off.

If the ASC service required message comes up on the dashboard, turn off the engine, remove the key from the vehicle, wait a few minutes, then restart the car.

In many cases, this simple procedure will reset the ASC warning message. If the ASC service light stays on, take a look at the common problems and the steps below for troubleshooting the Mitsubishi ASC system.

What Causes Mitsubishi ASC Warning? 

The ASC light can activate randomly or if the car isn’t maintained properly. Sometimes, the ASC Service Required light can be fixed by turning the car off and back on again.

The most common problems that trigger the Mitsubishi ASC warning light are:

1. Faulty ABS Wheel Speed Sensor
2. Defective Brake Light Switch
3. Electrical short
4. Misaligned suspension
5. Faulty ETACS brake control module
6. Blown fuse (Check ABS, Brake, and ETACS fuse)
7. Defective steering wheel angle sensor

1. ABS Wheel Speed Sensor

The ABS sensor issue provides the ASC computer information about the wheel speed. There are four sensors, each at one wheel.

The sensor can go bad with time; checking for damaged wiring or loose connectors is wise. Sometimes, deep water or snow can disrupt the sensor readings, but this usually goes away quickly.

2. Brake Pedal Switch

Various onboard computers use brake pedal switch signals to determine if the brake pedal is pressed. Most cars don’t allow drivers to start the engine without pressing the brake pedal; a faulty switch will cause non-starting issues. And even if it starts, this will still trigger the ASC warning message.

3. Short

Brake light bulb issues, as seemingly unrelated, can cause ASC warning messages. The cause for this can be something like corroded connectors or aftermarket LED bulbs with incorrect resistance. A blown brake light fuse will have an identical effect.

4. Misalignment / While size

Misaligned or unevenly worn tires, different size tires may offset the steering wheel angle sensor or difference in wheel spin speeds. The ASC computer won’t perform correct calculations because the steering wheel or ABS sensor will provide implausible readings.

If equipped, this will also disengage the 4WD system to prevent any damage. The ASC system is not crucial to operating the vehicle but is a good safety net when conditions become unsafe. 

If the ASC Service Required light activates and will not go off, take your car to a trusted mechanic or dealer and have them diagnose the problem.

How to Reset Mitsubishi ASC light

Troubleshooting the ASC warning sight on a Mitsubishi is easy, but it does require proper tools. To find out why your Mitsubishi ASC light is on, you will need to use an OBD-II ABS Scanner. Make sure the scanner can read ABS codes and works on Mitsubishi.

Here is how to diagnose Mitsubishi ASC / ABS.

1. Plug your ABS scanner into the OBD-II port under the dashboard. 
2. Turn on the ignition but do not start the engine. 
3. Turn on your scanner.
4. Select Mitsubishi from the main menu.
5. Select Anti-lock Brake System.
6. Select Read Codes or Read DTCs, depending on the scanner.
7. The scanner will display a diagnostic trouble code that describes the problem. Fix all codes that show current or present status. For now, ignore any codes that are stored (not active).

These steps work on any 1996, and newer Mitsubishi vehicles, including Galant, Outlander, Lancer, Montero, and Mirage equipped with ABS.

How to manually deactivate Mitsubishi ASC System

You can turn off the active stability control by pressing the “ASC” button on the dashboard for about three seconds. The ASC off light shows on the instrument cluster when the ASC system is deactivated. You should keep ASC on in most driving situations.

We hope you find the Mitsubishi ASC Service Required Warning – System Disabled guide helpful. Check these troubleshooting and repair guides for more help on your Mitsubishi.