DTC P1635: 5-Volt Reference 1 Circuit: Description
WARNING: This page is about a different car, the 2003 Pontiac Aztek and 2003 Buick Rendezvous. However, it is still accessible from the selected car via links, so may be relevant.
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.