Cummins fault code 387
Accelerator Pedal Position Sensor Supply Voltage Circuit: circuit voltage high / shorted high
What it means
Cummins' description: Accelerator Pedal Position Sensor Supply Voltage Circuit - shorted high.
SPN 1043 is Accelerator Pedal Position Sensor Supply Voltage Circuit. FMI 3 means the voltage on the circuit is higher than possible for a good sensor, usually an open signal wire, a short to a power wire, or a failed sensor.
The accelerator pedal has position sensors and an idle validation switch so the ECM knows exactly what the driver is asking for. Cruise control, brake and clutch switches, PTO and vehicle speed inputs are also monitored.
What the lamp means
An amber (yellow) warning lamp means the engine can usually keep running, but the fault should be repaired soon, ideally the same day.
Green, yellow, red: three ways this can look
The same code can be a quick fix or a reason to shut down. Match your situation to the closest example.
Keep an eye on it
A pedal or switch code that set once and cleared, and the pedal works normally.
Schedule a repair
Cruise doesn't work, the pedal feels dead in spots, or the code keeps returning. Have the pedal or switch checked.
Stop and get help
Engine stuck at idle or the pedal not responding, especially with a red lamp. Don't drive it in traffic. You won't have reliable throttle.
Common causes
FMI 3 is an electrical or signal fault, so start with the circuit:
- Accelerator pedal sensor worn or failed
- Pedal connector corroded or loose
- Brake, clutch or cruise switch out of adjustment or failed
- Vehicle speed sensor or wiring fault
If the circuit checks out, the reading may be real. Other possibilities: pedal sensors disagreeing with each other; switch inputs that don't make sense together, like brake and throttle at once.
What you can check before calling
- Check whether the engine stays at idle no matter what you do with the pedal
- Look at the pedal connector under the dash
- Check whether cruise control works
Clearing the code without fixing the cause usually brings it right back, and on emissions systems it can restart derate timers.
Engines and sources
Cummins uses the same fault code numbers across its electronic engines, including on-highway models like the ISB/B6.7, ISL/L9 and ISX/X15, though not every code applies to every engine or software level. Source: Diagnostic Fault Codes for Cummins Engines. Always confirm with Cummins service information (QuickServe) for your engine serial number.
Same SPN, other failure types
- 283 SPN 1043 FMI 3
Engine Speed/Position Sensor #1 (Crankshaft) Supply Voltage Circuit: circuit voltage high / shorted high - 284 SPN 1043 FMI 4
Engine Speed/Position Sensor #1 (Crankshaft) Supply Voltage Circuit: circuit voltage low / shorted low - 443 SPN 1043 FMI 4
Accelerator Pedal Position Sensor Supply Voltage Circuit: circuit voltage low / shorted low - 496 SPN 1043 FMI 11
Engine Speed/Position Sensor #2 (Camshaft) Supply Voltage: root cause not known
Related Accelerator pedal and driver controls codes
- 349 SPN 191 FMI 16
Transmission Output Shaft Speed: reading above normal (moderately severe) - 431 SPN 558 FMI 2
Accelerator Pedal or Lever Idle Validation Switch: erratic or intermittent signal - 432 SPN 558 FMI 13
Accelerator Pedal or Lever Idle Validation Switch Circuit: out of calibration - 287 SPN 91 FMI 19
SAE J1939 Multiplexing Accelerator Pedal Sensor System Error: network data error - 489 SPN 191 FMI 18
Transmission Output Shaft Speed: reading below normal (moderately severe) - 242 SPN 84 FMI 10
Wheel-Based Vehicle Speed Sensor Circuit tampering has been detected: abnormal rate of change
Look up another code
Cummins fault code (like 1922), J1939 SPN and FMI (like SPN 3251 FMI 0), or an OBD-II code (like P0420).
Questions
What does Cummins fault code 387 mean?
Cummins fault code 387 is J1939 SPN 1043 FMI 3: Accelerator Pedal Position Sensor Supply Voltage Circuit - shorted high. In plain terms: accelerator pedal position sensor supply voltage circuit: circuit voltage high / shorted high.
Can I keep driving with Cummins code 387?
Usually for a short time, if the engine runs normally and no other warnings are on. Get it diagnosed soon, because many amber codes lead to a derate if ignored. Look at the green, yellow and red examples on this page to judge your situation.
What is the SPN and FMI for Cummins code 387?
SPN 1043 identifies the part or system (Accelerator Pedal Position Sensor Supply Voltage Circuit). FMI 3 describes the type of failure: circuit voltage high / shorted high.
What usually causes Cummins code 387?
The most common causes are: accelerator pedal sensor worn or failed; pedal connector corroded or loose; brake, clutch or cruise switch out of adjustment or failed.
Diesel down in the Midlands?
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