2016-2019 Cadillac ATS-V Parking Brake Problems and Adjustment

By Core Brake Parts Tech Team — Circleville, OH warehouse

Most 2016-2019 Cadillac ATS-V parking brake complaints come down to three things: a red parking brake light that keeps flashing, a SERVICE PARKING BRAKE message, or a brake that will not hold or will not release. The ATS-V uses an electric parking brake (EPB) switch that pulls a cable to small shoes inside the rear rotor hat, so most fixes are either a cable-tension release and recalibration or a set of worn or glazed parking brake shoes, not a failed caliper.

How the ATS-V Parking Brake Works

The ATS-V runs a Brembo system with six-piston fixed front calipers on two-piece 370 mm rotors and four-piston fixed rear calipers on one-piece 339 mm rotors. A fixed four-piston caliper has no built-in parking mechanism, which is why the ATS parking brake is a separate drum-in-hat design: a pair of shoes sits inside the hat of each rear rotor and expands against it when the cable is pulled.

Instead of a foot pedal, the cable is pulled by an electric parking brake module. Per the trade service write-up for the ATS, that module contains its own motor, apply and release actuators and a temperature sensor, checks its internal circuit-board temperature before acting, and reads wheel speed, engine torque, gear and brake pedal signals over the GM-LAN network. That is why the system behaves differently depending on whether the car is moving, in gear, or running.

The switch location depends on the transmission. GM's owner's manual puts it on the center console for manual-transmission cars and on the left side of the instrument panel for automatics.

Common Symptoms and What They Mean

Red light flashes and will not go steady

GM's manual says the red parking brake status light should flash and then stay on once the EPB is fully applied. If it keeps flashing, the brake is only partially applied or the system has a fault. The manual's instruction is to release the EPB and try again, and not to drive the car while the red light is flashing.

Amber light on

The amber light is the parking brake warning light, separate from the red status light. With the amber light on, GM says to hold the switch up until the red light stays on to apply it, or hold it down until the red light goes out to release it, and then have the system checked.

SERVICE PARKING BRAKE or RELEASE PARKING BRAKE message

SERVICE PARKING BRAKE means the system has detected a problem. RELEASE PARKING BRAKE appears if the EPB is on while the car is moving. Driving with it applied, even partly, overheats the rear shoes and can glaze them, which is a common reason a parking brake stops holding later.

Brake will not apply or release at all

Check the battery first. The manual is clear that with insufficient electrical power the EPB cannot be applied or released. A weak battery or a bad ground can look exactly like a failed module.

The car clicks or whirs on its own when parked

This is normal. GM notes the vehicle may apply the EPB automatically now and then while stationary to check that the system works.

Causes of a Weak or Sticking Parking Brake

• Worn or glazed shoes: Driving off with the brake partly applied, or hard launches against the automatic release, wears the small shoes. GM specifically advises avoiding rapid acceleration while the EPB is applied to preserve lining life.
• Shoes out of adjustment: After rotor replacement the shoes may need to be adjusted to the new hat, which Brake & Front End notes for the ATS drum-in-hat system.
• Cable tension not reset: If the cable was released for service and the module was never recalibrated, the brake may not reach full tension.
• Seized or rusted cable: Road salt gets into the cable sheaths over time, and a stiff cable can stop the shoes from releasing fully.
• Electrical faults: Low voltage, a blown EPB fuse, or a module that reads an out-of-range internal temperature will refuse to operate.

Releasing and Recalibrating the EPB

Before you pull the rear rotors you have to take tension off the parking brake cable, or the shoes will hold the hat. Brake & Front End publishes this service-release sequence for the ATS: block the drive wheels, ignition ON with the engine OFF, transmission in Park (automatic) or Neutral (manual), then hold the brake pedal down for the whole procedure. Press and hold the EPB switch down for about five seconds, watch for the PARK BRAKE lamp to flash, then release and immediately press and release the switch again. The cable tension is now fully released and you can let off the pedal.

After the job, the system has to be recalibrated so the module relearns cable travel. A factory or enhanced scan tool does this directly. Without a scan tool, the same source gives this sequence: ignition ON and brake pedal held, hold the EPB switch down for five to six seconds, release it, push it down momentarily, pull and reinstall the EPB MODULE fuse, then apply and release the EPB once. Confirm the red status light comes on steady when applied and goes out on release before you drive.

If the procedure does not clear the lights, stop there. A module fault needs proper diagnosis with a scan tool, not repeated cycling, and GM warns that repeated EPB cycles with the engine off can drain the battery.

Parts to Replace and What to Do at the Same Time

A parking brake that will not hold usually needs new shoes and hardware, and often the rear rotors, since the hat is the drum surface. If the inside of the hat is grooved or lipped, new shoes will not seat well against it. Browse parking brake shoes and brake hardware kits for the small parts, and replacement brake rotors if the hats are worn.

Because the rotors have to come off anyway, it is the right time to look at the pads. The ATS-V runs a low-metallic pad from the factory. Owners who track the car often step up the fronts; we carry the EBC SR-21 sintered race front pads for the 2016-2019 ATS-V and the EBC SR-11 sintered race front pad set for the ATS-V, both built for track use rather than daily quiet. For street-only cars, see our full range of brake pads.

Brake fluid is DOT 3 per GM's owner's manual. If you open the hydraulic side, use the type marked on the reservoir cap.

How Hard Is the Job?

Diagnosis and the release-and-recalibrate sequence are easy for any owner with a battery charger and patience. Replacing the parking brake shoes is a moderate job: the fixed rear caliper has to come off its mounts, the rotor comes off, and the shoes and springs inside the hat are fiddly. Brake & Front End notes that ATS caliper bracket bolts are torque-to-yield, so they should be replaced rather than reused and tightened dry to the factory service manual procedure, never with an impact wrench. If you do not have the service information and a torque angle gauge, this is a reasonable job to hand to a shop.

Frequently Asked Questions

Why does my ATS-V parking brake light keep flashing?

A continuously flashing red light means the EPB is only partly applied or has a fault. Release it and apply it again. If it still flashes, do not drive the car and have the system diagnosed.

Can I release the ATS-V parking brake with a dead battery?

No. GM states that without enough electrical power the EPB cannot be applied or released. Charge or jump the battery first.

Does the ATS-V parking brake use the rear calipers?

No. The rear Brembo calipers are fixed four-piston units. The parking brake is a set of shoes inside the rear rotor hat, pulled by a cable from the electric module.

Do I need a scan tool to change rear rotors?

A scan tool is the easiest way, but the published switch-and-pedal sequence releases cable tension, and the fuse-pull sequence recalibrates afterward without one.

Is it normal for the parking brake to apply by itself?

Yes. The system may apply itself periodically while the car is stopped to self-check, according to GM's owner's manual.

Sources

1. GM 2016 Cadillac ATS/ATS-V Owner's Manual - EPB switch locations, apply and release steps, warning lights, DIC messages, low-power behavior, DOT 3 fluid
2. GM 2017 Cadillac ATS/ATS-V Owner's Manual - same EPB operation and DOT 3 fluid confirmed for later model years
3. Brake & Front End: Brake Job, Cadillac ATS - drum-in-hat parking brake, EPB module design, cable release and recalibration procedures, torque-to-yield caliper fasteners
4. Automotive Rhythms: Brembo Braking Technology on the 2016 ATS-V - Brembo six-piston front and four-piston rear calipers, rotor sizes, low-met pads