Series 40E Troubleshooting – Section 6.1 Input Signals

Engine and vehicle sensors transmit input signals to the ECM by either:‪

• Controlling a reference voltage to produce an analog or digital signal (i.e. ICP, EOT)
• Generating an analog or digital signal voltage i.e. CMP, VSS
• Switching an analog 12 volt signal i.e. IVS, DDS

Section 6.1.1
Reference Voltage Sensors

Reference voltage sensors are supplied with a constant 5 V regulated voltage supplied by the ECM. A voltage regulator supplies the reference voltage (VREF) to these sensors. This voltage is changed by the sensor and the resultant signal is relayed back to the ECM. The ECM then compares the supplied VREF with the returned signal and determines the value of the variable being measured by matching the signal value with its internal programmed tables.‪