Chassis Control System Errors

Your car’s chassis control system is one of those things that likely sits in the far back of your mind. Most of the time, you probably aren’t aware of the careful adjustments it makes to ride quality systems like suspension, braking, and steering.

Then, one day, you start the engine, and the dash display gives you a warning message like “Chassis Control System Error” or “Electronic Stability Control System Failure,” and you’re left wondering what’s gone wrong.

If you’re lucky, it’s just a loose battery connection or a loose wiring harness, which can be fixed in a matter of minutes. However, some more serious faults can be much harder to fix. While your car will be reasonably safe to drive with an active chassis control system error, you’ll probably be unhappy with the new way it handles. It might even cause the car to go into “Limp Home” mode.

What Does Chassis Control Mean?

If you were to jump behind the wheel of an older car from the 1970s or 1980s, you’d probably find the ride quality appalling. The road would feel bumpy, the suspension system would feel bouncy, and the body roll from going fast around a corner would try to slide you across the seat, pressing you toward the door.

Whereas with a lot of modern-day cars, you drive down the road, and everything feels reasonably smooth. You can take corners with reasonable confidence that you aren’t going to put your shoulder into the door window, and you can go over a speed bump a little too fast without worrying about banging your head on the headliner.

Yet, for the most part, the physical components of suspension components, steering system engineering, and other ride quality features have only evolved by small degrees. So what gives? Why are modern-day cars so much smoother on the road?

The answer is: It’s the chassis control system automakers install into most modern cars, SUVs, and trucks.

However it sometimes goes by different names for different types of vehicles made by various automakers. Some call it electronic stability control; others call it intelligent ride control. While there are some variations on how they smooth out the ride quality, they generally do the same thing by reducing the G-forces the passengers feel inside the car, optimizing the handling, and improving ride quality.

Where Is the Chassis Control System Located

Where Is the Chassis Control System Located

The chassis control system module is sometimes located on the left frame rail of the car behind the cab. It might also be located near the firewall in the engine bay. In some trucks and SUVs with rear leaf spring suspension systems, the chassis control module might be mounted in the forward spring hanger bracket of the rear suspension.

It looks like a square or slightly rectangular, flat device that usually has a black plastic cover with two to four latching clips.

The Components of a Chassis Control System

There are several important elements within the chassis control system. Here again, different automakers give them different names, but they more or less do the same things.

Active Traction Control

Traction Control System (TCS)

Active traction control is usually the most noticeable part of a chassis control system. It monitors wheel performance and seamlessly alters the traction, braking, and other power performance features based on how it interprets the road conditions. Some cars even have traction control features that let you tell the chassis control system if the conditions are icy or if you’re on a gravel road or other surface that might affect the tire’s ability to grip.

The traction control system then does its best to ensure the car drives as smoothly as possible with the least risk of wheel slip. At the same time, the anti-lock braking system will try to imperceptibly dampen the impact force without slowing the vehicle down. Though the tiny braking force it applies improves the performance of the shock absorber. This helps optimize traction and handling while greatly reducing vibration in the interior for the best possible passenger ride comfort.

The traction control system also has a series of sensors that work in synergy to detect the change in wheel speed as well as any changes in the engine torque. It can then make a minute adjustment to help the car maintain a reasonably stable speed for the surface conditions.

Brake System Optimization

How car brakes work

Engine braking is also a feature built into many chassis control systems to optimize handling when cornering or braking. It closely monitors the car’s speed and compares that with the steering system’s data and the braking system. It can then alter the anti-lock braking system as needed to reduce the force that must be applied to the brake pedal when you need it most.  

Intelligent Trace Control

04 Intelligent Trace Control

The intelligent trace control component of the chassis control system helps improve cornering and handling by adjusting the braking force on each wheel for the driving condition. It does this by interpreting data from the steering system and the braking system. While also helping to reduce body roll or lean by optimizing the performance of the anti-roll bars.

What Are the Signs Of Problems With Your Chassis Control?

The signs of a chassis control system error often go beyond the obvious warning message on the digital dash display to potentially ugly handling and performance. Most drivers with a chassis control system problem notice:

  • Unresponsive steering
  • Uncomfortable ride quality
  • More vibrations and road noise
  • Poor braking performance
  • An ABS or brake system warning light
  • Excess body lean when cornering
  • The car goes into limp home mode

10 Key Causes of Chassis Control System Errors and Proven Diagnostic Methods to Identify Them

Chassis control system errors are usually related to some type of electronic gremlin, like a loose battery connection, a failing battery, or a problem with the wiring harness connection. If you’re lucky, it’s easy to spot and fix.

It can be very frustrating if you’re out of luck, leaving you cursing a blue streak about all the electronic nanny devices they build into cars. It could even end up being a double-whammy problem with the anti-lock braking system!

  • Loose Battery Connection or Corroded Terminals
  • A Dying Car Battery
  • A Loose or Damaged Ground Wire
  • A Loose or Damaged Wiring Harness
  • An ABS System Fault

Before you dig too deep into the technical aspects of diagnosing your chassis control system error, take a moment to check the battery and look for corrosion on the terminals. The chassis control system requires a constant and consistent flow of electricity to operate correctly. Even the slightest interruption can cause a system failure or cause it to throw an error message on the dash console. Once you make sure the battery is sound, you can look for other gremlins.

1. Loose Battery Connection or Corroded Terminals

Loose Battery Connection or Corroded Terminals

Checking the battery for obvious loose connections or corrosion on the terminals is the first and most obvious way to check for a chassis control system problem. If the Negative (Black) or Positive (Red) terminals are just a little bit loose, it can be enough to prevent the system from getting the power it needs.

How to Fix: Loose, then connect the hardware and apply some penetrating lubricant. Then, use wrenches or a ratchet to tighten the connections beyond finger tight.

If you see fuzzy white, green, or gray gunk on the positive red terminal, you might also be dealing with a corrosion issue caused by the electrolyte process. This, too, can prevent enough charge from getting to the chassis control system.

How to Fix: Loosen the connection hardware. Then, scrub everything down with an old toothbrush and paste made from equal parts of water and baking soda. Wipe it all dry, then tighten the connection hardware firmly on the terminals.

2. A Dying Car Battery

A Dying Car Battery

If your car battery is more than three to five years old and/or your alternator has a problem, low charge levels can also underpower the chassis control system. This is the next most logical assumption if the terminals look tight and clean.

The trick here is testing to ensure that the battery is causing the chassis control system error and not the alternator. You can use a voltmeter or multimeter to test the battery. If it gives you a reading of fewer than 10.5 Volts when the engine is running or less than 12.5 Volts with the engine off, then you likely have a dying battery to blame for your chassis control system woes.

You can take the car to a battery service center or auto parts store if you don’t have a multimeter or voltmeter. They can usually test it for you for free to help eliminate if it’s a battery or alternator problem.

How to Fix: Assuming it’s a dying battery alone, then a simple battery replacement might be the only way to get the chassis control system running normally again. If the battery isn’t sealed and the fluids are low, you might be able to top up its electrolyte levels with distilled water.

3. A Loose or Damaged Ground Wire

Bad Ground Connection On Cars-Meaning,Symptoms, Diagnosing and Solving The Problem

While you’re checking the battery, follow the black negative wire from the battery terminal down to where it grounds out on the car’s frame to ensure a loose connection isn’t causing the chassis control system problem. Usually, it’s bolted onto something big near the battery or the firewall.

Suppose it’s even a bit loose, or there’s rust surrounding the metal connection to the ground wire. In that case, it can cause intermittent changes in the electrical delivery from the battery to the chassis control system module. This can give the module fits, and it will throw the error code when it can’t get the consistent power it needs to monitor the car’s performance actively.

How to Fix: If it’s just that the ground wire came loose in its connection to the bolt, then tightening the bolt down again might be all that’s needed to give the chassis control system the consistent power it needs.

Though oftentimes, when a ground wire comes loose, there’s a rust and/or corrosion issue. If you see a little rust, sanding all the surfaces and perhaps installing a metal shim before tightening it down might suffice. Otherwise, you might need a mechanic to weld or repair the problem.

4. A Loose or Damaged Wiring Harness

A Loose or Damaged Wiring Harness

Wires make their way safely through your car through a conduit wiring harness with connections to the chassis control module and other critical components. If corrosion, vibrations, or accidental damage to the wiring harness has affected the connection with the chassis control system module, it could cause the car’s computer to throw the error warning on the dash console.

If the wires were coming out of the protective wiring harness loom or the connectors, look damaged or corroded. Then you likely found the reason why your dash console threw the error message.

How to Fix: If it’s just a matter of a loose wiring connection or minor corrosion on the connector, you can usually just tighten, clean, or replace it.

If a wire is shorted out or damaged, you might need to replace it altogether or pigtail a new wire, which usually requires a professional mechanic’s skills.

5. An ABS System Fault

An ABS System Fault

The chassis control system relies on minute changes in the braking system to improve handling and suspension performance. If the anti-lock braking system module has a problem, the ABS sensor goes bad or the wheel speed sensor fails, the chassis control system won’t be able to function properly, and it will throw the error message.

This isn’t the sort of thing you can diagnose with your eyes and hands alone. Though if you’ve ruled out all other options, and perhaps you’ve noticed your brakes performing a little oddly recently, you might want to hook the ECU to a code reader to check for ABS system fault codes.

  • Code U0121 indicates “Lost Communication With Anti-Lock Braking System (ABS) Module.”
  • Code C0221 is an OBD-II code that shows up when you have a problem with the right front wheel speed sensor. 
  • Code C0040 indicates a potential malfunction in one of the wheel speed sensors or the wheel speed sensor’s circuit.

How to Fix: An ABS system fault isn’t the sort of thing the average DIY mechanic can fix on their own. The wisest move here is to take the car to a professional mechanic.

The cost to replace an ABD sensor ranges from $150 to $400.

The cost to replace a bad-wheel speed sensor ranges from $75 to $125.

The average cost to replace a bad ABS module ranges from $650 to $850, with a lot of the expense being the part cost.

Frequently Asked Questions

Is It Safe to Drive with a Chassis Control System Error?

Technically, you can drive a car with a chassis control system error for a short distance without causing major engine damage. Though the car will ride rough, and you’ll likely notice some engine performance issues.

The real worry is that the chassis control system fault will cross the threshold where the ECU puts the car into Limp Home mode. This will limit you to low-speed driving and annoying engine performance. It might also drive up the repair cost to get the car out of limp-home mode.


If you start your car and the dash display flashes an error message for “Chassis Control System Error,” it’s wise to take a few minutes to look for some of the simple reasons for the problem. A quick look under the hood can help you see if it’s something simple like battery corrosion, loose battery connections, or a loose ground wire.

If you’ve got a multimeter or voltmeter handy, you can also test the battery and alternator. If either one is giving you a reading below 10 Volts with the engine running, you likely need a new battery and/or a new alternator.

While you’re at it, try to locate the rectangular chassis control system module near the passenger or driver’s side firewall, or on the left frame rail behind the cab. Check it for any loose or damaged wires. If all seems well at this point in your troubleshooting, you can hook the ECU up to a code reader. If it throws a code Code U0121, Code C0221, or Code C0040, the cause of your chassis control system error is likely in the anti-lock braking system, and you’ll definitely need to call a mechanic.

Jason Farrell

Written By

Jason Farrell

Jason Farrell is a certified master technician, the editor of Mechanic’s Diary in Pittsburgh, Pennsylvania. He is ASE (Automotive Service Excellence) certified and earned a Bachelor’s Degree in Automotive Technology from Pittsburg State University. With nearly 18 prior years of experience in the automotive field, he has extensive knowledge about Domestic, European, and other foreign makes and models of cars and light trucks. Jason’s experience working as a technician and service manager at dealerships, gave him the experience and know-how of most aspects of inspection, diagnosis, and repair from engine and drivability to electrical, HVAC, brakes, steering and suspension and everything in between.

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One Comment

  1. Pete Vinyard says:

    U1556-00 Lost communication with device on LIN bus current
    on a 2015 chevy 1500