DTC P1635: 5-Volt Reference 1 Circuit: Description
WARNING: This page is about a different car, the 2003 Cadillac Seville and 2003 Cadillac DeVille. However, it is still accessible from the selected car via links, so may be relevant.
The Powertrain Control Module (PCM) provides 5 volts to the following sensors:
- The Throttle Position (TP) sensor.
- The Manifold Absolute Pressure (MAP) sensor.
- The Exhaust Gas Recirculation (EGR) valve.
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 the PCM detects the voltage is out of tolerance, DTC P1635 sets.