P0561

Schematic:

The PCM monitors ignition voltage on circuit 439 at all times with reference to circuit 551 (ground) when the engine is running. Ignition voltage from circuit 439 can be read on the Scan tool as IGNITION 1 voltage. DTC P0561 sets when the PCM detects an instantaneous change in ignition voltage.

DTC PARAMETERS
DTC P0561 will set if ignition voltage changes more than 3 volts when:
^ Condition exists for longer than 0.5 seconds
^ Condition exists twice in one ignition cycle
^ Engine is running

DTC P0561 diagnostic runs continuously with engine running.

DTC P0561 is a type D DTC.

DIAGNOSTIC AIDS

IMPORTANT:
^ If DTC P1635 is also set, diagnose that DTC first.
^ DTC P1635 will NOT set if a short-to-B+ occurs (PCM service part #21024985 or 21024986).

A short to B+ on one of the 5 volt reference circuits (EGR position sensor, fuel tank pressure sensor, MAP sensor or TP sensor) may set DTC P0561. DTC P0562 and P0711 may also set as a result of a short to B+ on the five volt reference circuit.

To locate this intermittent problem, use Scan tool to monitor IGNITION 1 voltage while wiggling wires. Wiggling wires while monitoring IGNITION 1 voltage may locate the area where an open in the wiring exists.

Check fuse(s), battery terminals, generator charging post terminal and ignition switch harness connector for tightness.