"Steering Assist Is Reduced, Drive with Care" in XT5 - What's This?

If you find the steering wheel of your Cadillac XT5 has become less responsive and difficult to steer at low speed while maintaining a straight line, chances are there's an issue with your steering wheel assist. A warning message of "Steering Assist is Reduced, Drive with Care" may also light up on your dashboard.

Steering assist is reduced message highlights

• Common reasons:battery problems, software glitches, bad power steering
• How to fix:check the battery, update the software, use the scanner to read codes
• Possible consequences:loss of power steering
• Priority level:Medium
• Can you drive?Carefully
• DIY repair:Possible
• Repair price range:$0-$900

What is Steering Assist and How Does it Work?

Steering assist is a feature found in most cars that helps the driver maintain control over the car. It helps the driver stick to the appropriate lane and makes turning the steering wheel less tiresome. The system also helps stabilize the vehicle while driving in tight spaces or at low speeds. It's a standard program in some vehicles and an optional safety feature in others. 

The Cadillac XT5 has an electric power steering system. In this system, the Electric Control Unit controls the steering dynamics. When the steering system is activated, the car's electrical system supplies the electric motor with electric energy. The motor is located at the steering rack or the steering column's base. It also uses sensors that determine the torque needed to turn in either direction and how far the driver is turning.

The information is then sent to the ECM-Electronic Control Module- which uses the information to add a proportional amount of additional force to the input of the steering wheel. The steering assistance also comes in handy in cases of oversteering or loss of traction to help avoid accidents.

What the "Steering Assist is Reduced Drive with Care" Message Means

If you spot the warning light with the "Steering Assist is Reduced Drive with Care" message on your Cadillac XT5, it's usually a sign of an issue with your steering assist feature. This means you've lost the steering wheel assist feature's benefits, and it's your responsibility to apply the right amount of torque to the steering wheel without the additional support. The diagnostic trouble code commonly associated with the issue is P0128 • U0401.

Causes of the "Steering Assist is Reduced Drive with Care" Warning Message

Several reasons can lead to the failure of the steering wheel assist feature. Below are some of the most common ones to help pinpoint what's causing the failure and help you make the correct diagnosis.

• A Stuck Thermostat

This is one of the leading causes of malfunctioning steering assist in Cadillac, Chevrolet, and GMC cars. You may wonder how a stuck thermostat is associated with the steering wheel assist. Here's how:

The role of a thermostat in a vehicle is to regulate the engine's cooling system. It does this by monitoring the coolant's temperature and controlling the flow of the coolant through the radiator. This is meant to keep and maintain a constant optimum engine operating temperature. A failing thermostat can either be stuck in an open or closed position.

If it's stuck in a closed position, it causes the engine to overheat since the coolant flow is blocked, and the coolant can't access the radiator for cooling. A continuous coolant flows into the radiator when stuck in an open position. This leads to overcooling of the coolant, which causes the engine to run cold. 

The steering wheel module has grease, which helps it run. Whenever the engine runs at optimum temperature, the grease becomes softer and lighter, making controlling the steering wheel much more effortless. When the thermostat fails in an open position causing the engine to run cold, the grease becomes more viscous, making the steering wheel stiffer. This can lead to failure of the steering assist, leaving you with a heavier steering wheel.

Signs that a thermostat needs replacing are the build-up of deposits, scale, and sludge which clogs the thermostat, rust and corrosion on the thermostat surface, and signs of leakage on the thermostat's housing surface.

• Failure of the Electric Control Module

One of the functions of the ECM is to receive information about the coolant temperature from the temperature sensors and adjust accordingly. Whenever it's cold or the engine is running cold, it sends signals to the steering assist to help control the steering wheel.

This is because the fluid in the steering wheel module turns hard, and a lot of effort is required to turn the steering wheel. Failure of the ECM prevents it from sending accurate signals to the steering assist. This stops the steering assist from making the proper response causing the warning light and error code to appear on the dashboard.

• Faulty Temperature Sensor

The coolant temperature sensor's work is to measure the temperature of the coolant to determine how much heat the engine is emitting. It then relays the readings to the Electronic Control Module.

The ECM then responds accordingly by controlling the switching on or off of the electric cooling fan and adjusting the fuel injection and ignition timing. If the engine's temperature is high, the thermostat allows the coolant to enter the radiator. The fan is then switched on to blow away excess heat in the radiator.

If the temperature sensor goes bad, the engine may overheat or become too cold since the correct readings are not sent to the ECM. This has a ripple effect on the steering assist making it defective. 

• A Battery with Low Voltage

A battery powers the electrical components of the car. If the battery has low voltage, some electrical components begin to malfunction. One of those electric components is the steering assist feature.

As a result, a warning message of Steering Assist is Reduced Drive with Care illuminates on the dashboard. A loose or corroded wire from the battery and corroded terminals on the alternator may also cause the issue.

• A Flawed Steering Assist Module

The power steering module reads the ECM data and activates the steering assist feature if need be-such as in cold weather conditions. If the steering assist module doesn't work correctly, it'll not act appropriately since it's not receiving the correct signal from the ECM or the signal is facing interruption.

Consequently, the steering wheel doesn't respond to the driver's input. This leads to the appearance of the warning message and the diagnostic trouble code. Another related component that can cause the steering assist to fail is the electric power steering column magnet. The magnets are part of torque and angle sensors and measure the steering wheel position and how much force you apply to the steering wheel.

Signals are then relayed to the ECM to apply the desired torque. Damage to the magnets prevents them from functioning properly.

How to Fix a Failing Steering Assist

There are various ways you can fix a faulty steering assist. These are:

• Replacing the Damaged or Broken Parts

Whenever you see the Steering Assist is Reduced Drive with Care Message on the infotainment system of your XT5, you first have to inspect the parts associated with the steering assist to see if there are any issues.

Some parts are easier to replace and easily handled by do-it-yourselfers, while others are uphill tasks. For instance, changing a battery might be easy but replacing a thermostat is a different ball of wax. It would help if you also made the correct diagnosis of what's causing the steering assist to fail before committing to replacing a component.

This will save you the time, cost, and headache of replacing the wrong part. Other components you can replace are the temperature sensors and the cooling fan. 

• Checking the Car Battery

If you see the message Steering Assist is Reduced Drive with Care, one of the places to check is the car battery. You need first to confirm if the alternator is correctly charging your battery when your car is running. A simple way is to monitor if the dashboard light and interior lights come on brightly and then start to fade slowly.

This is a sign the alternator isn't working correctly. You can also test the voltage of the car battery using a multimeter. Do this by resetting your multimeter to DC Volts of above fifteen. Then connect the negative and positive cables to the corresponding terminals on the battery. The alternator reading should be about 12.6.

Follow it up by starting the car and checking for reading between 14.2 and 14.7. If you get a reading below 14.2, it's a sign of undercharging of the alternator, while a reading of over 14.7 is a sign of overcharging of the alternator.

• Reading and Clearing the Diagnostic Trouble Codes

A high-end code scanner comes in handy when reading the diagnostic trouble codes set in the computer. Ensure your code scanner is compatible with your vehicle. If you experience any trouble codes, you need to reset the codes.

Many mechanics have a database of standard diagnostic trouble codes to determine the proper fixes. Once you figure out the correct fix, the next step is to clear the code, which makes the Steering Assist is Reduced Drive with Care message disappear.

• Consult Your Mechanic

If you cannot make the proper diagnosis, your last option would be to consult a mechanic to find out what the issue might be. The Auto shops have advanced tools that can quickly determine the problem.

You may also need a mechanic if you don't have the right tools for the repair and replacement of the affected parts. It is also best to visit the dealership if your warranty hasn't expired to avoid incurring the costs of replacing the affected parts.

Bottom Line

There you have it-possible causes of the "Steering Assist is Reduced Drive with Care" warning message and various ways you can fix the issue. You can make the diagnosis independently or consult a mechanic if you don't have the necessary skills or tools.