DTC P1635: 5-Volt Reference 1 Circuit: Description

The PCM uses the 5-volt reference 1 circuit as a sensor feed to the following sensors:

• TP sensor.
• MAP sensor.
• EGR valve pintle position sensor.
• Fuel Tank Pressure (FTP) sensor.

These 5-volt reference circuits are independent of each other outside the PCM, but are bussed together inside the PCM. Therefore, a circuit condition on one sensor 5-volt reference circuit may affect the other sensor 5-volt reference circuits. The PCM monitors the voltage on the 5-volt reference circuit. If PCM detects that the voltage is out of tolerance, DTC P1635 sets.