DTC P1635: 5-Volt Reference Circuit: Description

The 5-volt reference circuit provides a signal voltage to the EGR valve position sensor, fuel tank pressure sensor, MAP sensor and TP sensor. The current for each 5-volt reference circuit flows through the sensor ground in the PCM. The PCM regulates the 5-volt reference voltage under all normal operating conditions. PCM monitors 5-volt reference circuit for low and high voltage faults. DTC sets when 5-volt reference circuit is outside a calibrated voltage range.