5005758 | Genuine Paccar® Air Brake Pressure Sensor 150-PSI

1. Safety Monitoring

The air brake system must maintain a certain pressure (usually 90–120 PSI).
If pressure drops too low, the brakes can fail or automatically engage (spring brakes).
The sensor helps detect this before it becomes dangerous.

Without this sensor: The driver might not know air pressure is too low until it’s too late.

2. Driver Alerts / Dash Warnings

Sends signals to the instrument cluster to activate:
Low air pressure warning lights
Buzzers or alerts
Lets the driver know something’s wrong—before brake failure occurs.

3. System Feedback for ECU / ABS

Provides real-time pressure data to:
ABS (Anti-lock Braking System)
ESC (Electronic Stability Control)
Brake Control Modules (BCM)
Helps the truck’s brain make smart decisions under braking (like preventing wheel lockup).

4. Compliance with DOT / FMVSS Regulations

U.S. regulations (like FMVSS 121) require low-air warnings and system monitoring in air brake-equipped vehicles.
The sensor is part of that compliance.

5. Diagnostics & Maintenance

Allows:
Mechanics to read pressure data via diagnostic tools.
Telematics systems to log pressure issues remotely.
Helps identify:
Leaks
Weak compressors
Failing valves

1. Low Air Pressure Warning Light (or Buzzer) Stays On

Even if your air tanks are full and the compressor is working.
The sensor may be sending the wrong (low) signal to the dash.
False warning due to incorrect voltage signal from sensor.

2. No Warning — Even When Pressure Is Low

Dangerous: the sensor fails to alert the driver.
The vehicle might lose braking power without warning.
This can lead to emergency brake application (spring brakes engage suddenly).

3. Erratic or Fluctuating Pressure Readings

Digital dash or diagnostic tool shows:
Jumping PSI values
Unstable air pressure readings
May cause the system to trigger ABS or ESC faults.
Sensor is sending inaccurate or unstable voltage to ECU.

4. Diagnostic Trouble Codes (DTCs)

Codes may include:
Air pressure signal out of range
Voltage too high/low
Pressure sensor circuit fault
Retrieved using scan tools or via the truck’s telematics system.
Especially common in Peterbilt, Kenworth, and other PACCAR vehicles.

5. Brake System Fault or ABS Warning

The truck might show:
ABS or traction control lights
Service brake system warning
Some systems depend on accurate air pressure to function properly.
If the ECU gets bad data, it may disable ABS or other systems.

6. Unusual Brake Behavior

Brakes might:
Apply late or too hard
Not release properly
Engage spring brakes without warning
Can be dangerous at highway speeds or when parking.

7. Electrical or Grounding Issues

Sensor might short internally or backfeed power.
Can cause weird electrical symptoms, like:
Other sensors failing
Dashboard glitches