CM870 and ISX Engines – FAULT CODE 284

Engine Speed Sensor Supply Voltage Circuit


Fault Code: 284
PID: S221
SPN: 1043
FMI: 4/4
LAMP: Amber

Engine Speed Sensor Supply Voltage Circuit – shorted low. Incorrect voltage detected on the ECM voltage supply line to the engine speed sensor.

Possible hard starting and rough running.

Engine Speed Sensor Supply Voltage Circuit

Circuit Description

The ECM supplies the engine speed sensor with +5 VDC.

Component Location

The engine speed sensor is located in the lower portion of the front cover on the intake side of the engine. Refer to Section E for a detailed component location view.

Shop Talk

The ECM monitors the voltage level on the engine speed sensor +5 volt supply circuit. If voltage falls below a calibratible limit then this fault is recorded.

Possible causes of this fault code are a short circuit to ground in the engine harness, sensor, or ECM.

Refer to Troubleshooting Fault Code t05-284

Last Modified:  01-Sep-2010