D21-6024 | Genuine Paccar® Accelerator Pedal Assembly For Peterbilt

Instead of a steel cable directly pulling open the throttle valve, the pedal sends electronic signals to the engine computer (ECM).
The ECM interprets the driver’s input and precisely adjusts:
Throttle opening
Fuel injection
Turbo boost (in diesels)
Transmission response

Result: smoother acceleration, better fuel efficiency, and optimal air-fuel ratio at all times.

2. Improved Fuel Economy & Emissions

The ECM can limit throttle response to reduce fuel consumption and emissions under certain conditions (like idle or cruise).
Helps the truck meet EPA and CARB emission regulations.
Especially important for modern diesel engines in Peterbilt, Kenworth, Freightliner, etc.

3. Integration With Vehicle Systems

Electronic throttle allows the pedal signal to be shared across many systems:
Cruise control — ECM holds throttle electronically, no mechanical linkage needed.
Traction control & stability control — system can reduce engine torque electronically.
Idle management / PTO (Power Take-Off) — ECM adjusts engine speed automatically for accessories.
Adds flexibility for safety and convenience features that mechanical throttles couldn’t support.

4. Reduced Maintenance

No mechanical cables or linkages to stretch, rust, or break.
Compact assembly with fewer moving parts.
Longer service life and easier installation in modern cab layouts.

5. Safety & Diagnostics

Pedal assemblies use dual redundant sensors (two position sensors giving matching signals).
If one fails, the ECM detects the mismatch and activates a “limp mode” for safe operation.
Improves reliability and allows for self-diagnosis through onboard fault codes.

6. Drive Customization

The ECM can re-map throttle sensitivity (for example, “Eco” vs “Performance” modes).
Enables customizable driving characteristics without changing hardware.

1. Slow Brake Release

Brakes take too long to release after you let go of the pedal.
You may feel the vehicle dragging or resisting movement for a moment.
This is the most common symptom of a failing quick release valve.

2. Hissing Air Leaks

You hear a constant hissing sound from the valve area, even when the brakes are not applied.
This usually means there's an air leak in the valve or one of its seals.

3. Brake Drag or Overheating

Brakes stay partially applied, especially on the rear axle.
This can cause heat buildup, uneven brake wear, or reduced fuel efficiency.

4. Uneven Brake Release (Pulling)

The vehicle pulls to one side when brakes release unevenly.
Often happens if only one quick release valve is failing, affecting one side or axle more than the other.

5. Reduced Air Pressure Efficiency

You may notice longer refill times for the air tanks or lower system pressure.
A leaking or stuck valve can cause the system to lose pressure faster than normal.

6. Physical Damage or Corrosion

Visible cracks, rust, or loose fittings on the valve.
May be caused by road debris, age, or exposure to moisture/salt.