SAE J1939 diagnostic codes for brake systems. Includes SPN and FMI fault codes for electronic brake controllers, ABS, EBS, park brake, hydraulic braking systems, and brake temperature monitoring on heavy-duty trucks and trailers.
Diagnostic Code SPN 1067 FMI 21: Meaning and Fix SPN 1067 FMI 21 identifies that the Brake Signal Sensor 1 analog output has drifted below its calibrated lower threshold without reaching a hard short-to-ground condition. The ECM interprets this gradual signal decay as an unreliable brake input. This fault commonly appears in vocational trucks operating … Read more
Diagnostic Code SPN 1067 FMI 20: Meaning and Fix SPN 1067 with FMI 20 indicates a high drift in the Brake Signal Sensor 1 data. This fault is often encountered after replacing the ECM or following an update, where the brake signal sensor’s data calibration might be disturbed. Technicians may notice the fault during routine … Read more
Diagnostic Code SPN 1067 FMI 19: Meaning and Fix SPN 1067 FMI 19 triggers when the brake signal sensor 1 transmits data that the receiving ECM detects as invalid or out-of-range under J1939 protocol. Technicians frequently encounter this fault after a brake controller replacement if the new unit is not properly parameterized. In practice, this … Read more
Diagnostic Code SPN 1067 FMI 17: Meaning and Fix SPN 1067 FMI 17 indicates the Brake Signal Sensor 1 is transmitting a valid but sub-threshold signal, classified as least-severe under SAE J1939 FMI definitions. The ECM registers brake pedal position data falling below the calibrated lower operating boundary without a hard electrical failure. This fault … Read more
Diagnostic Code SPN 1067 FMI 16: Meaning and Fix SPN 1067 with FMI 16 indicates that the Brake Signal Sensor 1 is providing data considered valid but above its normal operating range, suggesting a moderately severe issue. This code often appears in practice when a braking system component, such as a sensor or wiring, malfunctions … Read more
Diagnostic Code SPN 1067 FMI 8: Meaning and Fix SPN 1067 FMI 8 flags an abnormal frequency, pulse width, or period detected on Brake Signal Sensor 1, indicating the ECM has received a signal outside its calibrated timing window. The ECM continuously monitors the brake switch pulse pattern; when the period deviates beyond tolerance, this … Read more
Diagnostic Code SPN 1067 FMI 15: Meaning and Fix SPN 1067 with FMI 15 indicates that the Brake Signal Sensor 1 is outputting data above its normal operating range. Although considered least severe, this fault can still signal potential issues in the braking system. Commonly, this code appears after a brake sensor calibration procedure or … Read more
Diagnostic Code SPN 1067 FMI 10: Meaning and Fix SPN 1067 FMI 10 indicates the Brake Signal Sensor 1 reports an abnormal rate of change, exceeding the ECM’s plausibility threshold. This fault commonly appears after a forced DPF regeneration when brake pedal vibrations cause sensor noise, or when a technician accidentally bends the sensor bracket … Read more
Diagnostic Code SPN 2919 FMI 18: Meaning and Fix This fault indicates the Electronic Brake Controller 5 (EBC5) reports foundation brake use status (SPN 2919) as data valid but below normal operational range. Typically triggered when the brake pedal position sensor voltage drops below 0.5 V during a self-test cycle. Technicians often see this after … Read more
Diagnostic Code SPN 1243 FMI 3: Meaning and Fix The SPN 1243 FMI 3 fault code indicates an issue with the ABS system, specifically that the voltage is above normal, or there’s a short to high on the Electronic Brake Controller. This fault is often encountered after a vehicle undergoes extensive off-road operations or after … Read more