DTC P1635: 5-Volt Reference 1 Circuit: Description
WARNING: This page is about a different car, the 2002 Oldsmobile Aurora. However, it is still accessible from the selected car via links, so may be relevant.
The Powertrain Control Module (PCM) uses the 5-volt reference 1 circuit as a sensor feed to the following sensors:
- The Throttle Position (TP) sensor.
- The Manifold Absolute Pressure (MAP) sensor.
- The Exhaust Gas Recirculation (EGR) valve pintle position sensor.