DTC P1635: 5-Volt Reference 1 Circuit: Description

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.