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What is the difference between auto and full exhaust brake RAM?

On RAM heavy‑duty pickups with diesel engines, the exhaust brake helps slow the vehicle by creating backpressure in the exhaust system. The Auto setting and the Full setting describe how aggressively that braking force is applied and how it’s controlled. In short: Auto modulates braking automatically for smoother everyday use, while Full delivers maximum braking when you need it most.

Overview of RAM exhaust braking

Exhaust braking works by restricting exhaust flow with an electronically actuated valve, which increases engine braking and reduces reliance on the service brakes. The RAM system can be activated via a dash control and is often integrated with Tow/Haul mode to optimize downhill control, speed, and transmission behavior.

Auto exhaust brake: how it works

In Auto mode, the exhaust brake is automatically engaged and modulated by the vehicle’s engine control module based on driving conditions. It uses data such as vehicle speed, engine load, throttle position, and transmission state to apply a graduated amount of backpressure. The goal is smooth deceleration during deceleration phases without requiring driver input, especially on moderate downgrades or when towing.

Key characteristics of Auto mode:

Automatic engagement during deceleration without driver intervention

Adaptive backpressure via valve modulation for smooth braking

Typically integrates with Tow/Haul and cruise control on downgrades

Breathes off automatically when conditions no longer require braking

Designed for everyday driving and moderate grades

Auto mode provides consistent engine braking with a focus on comfort and control rather than maximum stopping power.

Full exhaust brake: maximum braking

Full exhaust brake uses the maximum available backpressure to deliver the strongest engine braking performance. This setting is intended for situations that demand rapid deceleration, such as long, steep downhill grades or when towing heavy loads on steep descents. It is usually activated by the driver via a dedicated switch or control and remains engaged until manually reduced or turned off.

Key characteristics of Full mode:

Maximum backpressure for strongest deceleration

Typically a manual control, activated by the driver

Ideal for long downgrades and heavy towing where aggressive braking is needed

Can cause higher exhaust temperatures and a more abrupt deceleration

May require more careful speed management on curves or in traffic

Full mode provides the most decisive engine braking, but it is less forgiving for everyday driving and can be taxing on the drivetrain if overused.

When to use Auto vs Full

Choosing between Auto and Full depends on road grade, payload, and driving goals. Here’s guidance to help decide when to engage each setting.

Auto: Use for routine highway driving, light to moderate downgrades, and when towing light-to-moderate loads. It offers automatic, smooth braking without driver input.

Full: Use for long, steep downgrades, heavy towing, or when you need immediate, strong deceleration. It provides the highest braking force but can be less smooth and may raise exhaust temperatures.

Note: Availability and behavior of Auto and Full modes can vary by model year and trim. Always consult your owner’s manual for exact operation and any recommendations about when to use each setting.

Summary

The RAM exhaust brake system offers two modes: Auto and Full. Auto uses the engine control module to automatically modulate backpressure for smooth, everyday engine braking, while Full delivers maximum backpressure for the strongest deceleration during demanding downhill or heavy-towing conditions. Use Auto for normal driving and gentle downgrades, and switch to Full for extended descents or heavy loads. Always monitor engine temperature and vehicle speed to maintain safe control.

What's the point of an exhaust brake?

An exhaust brake slows a vehicle by creating back pressure in the exhaust system, forcing the engine to work harder and thus slowing it down. This supplemental braking system is especially useful for heavy vehicles like diesel trucks, as it reduces wear and tear on the conventional wheel brakes and helps prevent overheating, particularly on long downhill grades.

This video explains how an exhaust brake works and its benefits: 1mThe Bundy Ranch YouTube · May 29, 2023
How it works

When activated, an exhaust brake partially closes a valve in the exhaust pipe, typically controlled by the turbocharger or a separate butterfly valve.
This action traps exhaust gases, increasing pressure upstream from the valve.
This high-pressure gas pushes back against the pistons as they move upward, making it more difficult for the engine to rotate.
The increased effort required to turn the engine creates a braking force that slows the vehicle down, similar to a downshift but without a gear change.

Benefits

Extended brake life: By handling a significant portion of the slowing on inclines, it reduces the need to use the wheel brakes, which prolongs the life of brake pads, rotors, and drums.
Reduced brake fade: It prevents the conventional brakes from overheating, which can lead to a loss of stopping power known as brake fade.
Improved control: It provides a more stable and controlled descent on long grades, especially when towing or hauling heavy loads.
Cleaner turbo: Some systems help keep the turbocharger clean by using the back pressure to clear soot from the turbocharger veins.

You can watch this video to learn about the benefits of using an exhaust brake: 29sJB ReviewsYouTube · Sep 6, 2025
When to use it

An exhaust brake is most effective when driving downhill, especially with a heavy load.
It is engaged manually or by putting the vehicle in a tow/haul mode, and it automatically activates when the driver lifts their foot off the accelerator.
It is crucial to disengage the exhaust brake in slippery or icy conditions, as the engine braking force can cause the rear wheels to slide and lead to a loss of control.

What is auto exhaust brake ram?

The exhaust brake will automatically operate when the driver removes pressure from the accelerator. Pedal for optimal braking. Power put the vehicle into tow hall mode. And the engine will downshift

How does the exhaust brake work on a 6.7 Cummins?

An exhaust brake on a 6.7L Cummins works by using its variable geometry turbocharger (VGT) to create back pressure and slow the vehicle down. When the brake is activated and the driver lifts their foot off the accelerator, the turbo's internal vanes close to restrict exhaust flow. This back pressure forces the engine to work harder to push out the exhaust, creating a retarding force that slows the vehicle, similar to how a traditional engine brake works but by manipulating the exhaust flow instead of the valves.
How it activates and operates

Normal/Full mode: Pushing the exhaust brake button once typically engages the full exhaust brake, indicated by a yellow light. The brake will automatically activate when you lift your foot off the accelerator, and the engine will also downshift for more power.
Automatic/Smart mode: Pressing the button a second time often engages the automatic mode, indicated by a green light. The brake will activate automatically when it senses you're descending a grade or when you lightly tap the brake pedal.
Towing: Engaging Tow/Haul mode will cause the exhaust brake to function more aggressively for greater braking power when towing or carrying a heavy load.
Disengagement: The exhaust brake deactivates when the vehicle slows to a certain speed or the engine RPMs drop below a set threshold, typically around 1,000-1,100 RPM.
Increased power: Tapping the brake pedal while the exhaust brake is active will triple its effectiveness, making it more powerful.

This video explains the different modes of the exhaust brake and how to use them: 51sMoparYouTube · Jul 25, 2023
Important considerations

Maintain the turbo: Regularly using the exhaust brake is recommended because it helps prevent the turbo's vanes from seizing up from carbon buildup.
Avoid slippery conditions: Do not use the exhaust brake in icy or slippery conditions, as it can cause a loss of control.
Aftermarket vs. factory: The factory exhaust brake is integrated into the VGT turbo. Aftermarket inline exhaust brakes are separate components that can provide more retarding power but may not be compatible with some engine modifications.

What is the difference between a full exhaust brake and an auto exhaust brake?

Full exhaust brake mode engages automatically as soon as the accelerator is released, while automatic mode only engages when the brake pedal is lightly tapped or when the vehicle is actively gaining speed downhill, allowing for more control and potentially better fuel economy. The full mode is more aggressive and provides continuous braking to reduce speed, whereas the automatic mode maintains speed or provides braking on demand. Automatic mode is often recommended for general driving and stop-and-go traffic, while full mode is beneficial for heavy towing or steep descents.
This video demonstrates the difference between full and automatic exhaust brake modes: 1mJB ReviewsYouTube · Dec 5, 2019

Feature	Full Exhaust Brake	Automatic Exhaust Brake
Activation	Automatically engages when you lift your foot off the accelerator.	Engages when you tap the brake pedal or when the vehicle's speed increases on a downgrade.
Primary Function	To actively reduce vehicle speed.	To maintain a set speed or provide braking when needed, without constant engagement.
Driver Control	Less direct control, as it is always on when you are off the gas.	More direct control, as you decide when to activate it by tapping the brake.
Best For	Steep descents and heavy towing where constant slowing is needed.	Everyday driving and stop-and-go traffic, as it allows the vehicle to coast more freely.
Fuel Economy	May slightly reduce fuel economy because it can keep engine RPMs higher.	Can improve fuel economy by allowing the vehicle to coast without engine braking until needed.

Kevin Bennett

Company Owner

Kevin Bennet is the founder and owner of Kevin's Autos, a leading automotive service provider in Australia. With a deep commitment to customer satisfaction and years of industry expertise, Kevin uses his blog to answer the most common questions posed by his customers. From maintenance tips to troubleshooting advice, Kevin's articles are designed to empower drivers with the knowledge they need to keep their vehicles running smoothly and safely.