DTC P1635: 5-Volt Reference 1 Circuit: Description
WARNING: This page is about a different car, the 2002 Pontiac Aztek and 2002 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:
- The TP sensor.
- The MAP sensor.
- The EGR valve pintle position sensor.
- The Fuel Tank Pressure (FTP) sensor.
The PCM monitors the voltage on the 5-volt reference 1 circuit. If the voltage is out of tolerance, the PCM will set DTC P1635.