P0643

DTC P0643 5 Volt Reference 1 Circuit High Voltage

Circuit Description

The ECM provides 5 volts reference voltage through the reference circuit 1 to the following sensors:

^ Accelerator pedal position (APP) sensor 1
^ Fuel rail pressure (FRP) sensor
^ Boost pressure sensor
^ Camshaft position (CMP) sensor
^ Engine oil pressure (EOP) sensor
^ Idle speed selector sensor
^ PTO throttle sensor

The 5 volts reference circuits are independent of each other outside the ECM but are bussed together inside the ECM. Therefore a short circuit condition on one 5 volts reference circuit affects the entire 5 volts reference circuit 1. The ECM monitors the voltage on the 5 volts reference circuit 1. If the ECM detects the voltage is excessively high this DTC will set.

Condition for Running the DTC

^ DTC P0642 is not set.
^ The battery voltage is between 10 to 16 volts.
^ The ignition switch is ON.

Condition for Setting the DTC

^ The ECM detects that the 5 volts reference circuit 1 voltage is more than 5.5 volts.

Action Taken When the DTC Sets

^ The ECM illuminates the MIL when the diagnostic runs and fails. Refer to DTC Type Definitions for Action Taken When the DTC Sets - Type A.
^ The ECM inhibits accelerator pedal control.
^ The ECM inhibits EGR control.
^ The ECM inhibits DPF regeneration control.
^ The ECM inhibits cruise control.
^ The ECM inhibits PTO control.

Condition for Clearing the DTC

^ Refer to DTC Type Definitions for Condition for Clearing the MIL/DTC - Type A.

Diagnostic Aids

^ If an intermittent condition is suspected refer to Intermittent Conditions in this section.

Notice: If this DTC is active, the engine cranks but does not start.

Circuit/System Testing DTC P0643