PACCAR PX-9 CM2350 (2013-17) Fault Code:234 PID:190 SPN:190 FMI:0 Engine Crankshaft Speed/Position – Data Valid But Above Normal Operating Range – Most Severe Level

Reason:
Engine Crankshaft Speed/Position – Data Valid But Above Normal Operational Range – Most Severe Level. Engine speed signal indicates engine speed above engine protection limit.

Effect:
Possible reduced engine performance.

Circuit Description:
The crankshaft position and camshaft position sensors are Hall effect type sensors. The engine control module (ECM) provides a 5 volt supply to the position sensor and a return circuit. As the teeth on the crankshaft speed ring or the dimples in the back of the camshaft gear move past the position sensor, a signal is generated on the position sensor signal circuit. The ECM interprets this signal and converts it to an engine speed. A missing tooth on the crankshaft gear is used by the ECM to determine the position of the engine.

Component Location:
The crankshaft position and camshaft position sensor location varies, depending on engine model.

Conditions for Running the Diagnostics:
This diagnostic runs continuously when the engine is running.

Conditions for Setting the Fault Codes:
The Engine Control Module (ECM) detected the engine speed had exceeded the calibration limit.

Action Taken When the Fault Code is Active:
1) The ECM illuminates the red STOP ENGINE lamp immediately after the diagnostic runs and fails.
2) Fueling to the engine is stopped until the engine speed drops to normal operating speeds.

Conditions for Clearing the Fault Code:
1) To validate the repair, perform a key cycle, start the engine and let it idle for 1 minute.
2) The fault code status displayed by INSITE™ electronic service tool will change to INACTIVE immediately after the diagnostic runs and passes.
3) The ECM will turn off the red STOP ENGINE lamp immediately after the diagnostic runs and passes.
4) The Reset All Faults command in INSITE™ electronic service tool can be used to clear active and inactive faults, as well as extinguish the MIL for OBD applications.

Shop Talk:
If Fault Code 234 becomes active only during engine braking, and the engine brakes fail to engage, check for a short circuit to ground in the engine brake wiring harness. The rocker lever cover must be removed to perform this inspection. Repair or replace the engine brake wiring harness as necessary.

Possible Causes:
1) External fuel sources drawn into the intake air passage
2) Reverse powering (motoring) of the engine
3) Tampering of the engine speed/position sensors.
4) Inspect the intake manifold for sources of flammable vapors. Check the turbocharger seals to verify there are no oil leaks. Inspect the engine speed/position sensors for damage or tampering.