P0561

Wiring Diagram:

The PCM monitors ignition voltage on circuit 439 when powered up. The purpose of this diagnostic trouble code is to detect an unstable ignition voltage to the PCM.

DTC PARAMETERS
DTC P0561 will set if ignition voltage changes more than three volts instantaneously.

IMPORTANT: The PCM monitors system voltage continuously when the engine is running. The system must fail twice per ignition cycle in order to set a DTC.

DIAGNOSTIC AIDS
If P1635 is also set, diagnose P1635 first. A short to B+ on the five volt reference line will cause a false set of P0560, P0561 or P0563.

Wiggle the PCM connector. Watch Scan tool to see if battery voltage reading changes sharply.

Wiggle and tug the harness at the ignition switch. Watch Scan tool to see if ignition voltage changes sharply. Lightly tap the PCM. Watch for changes in the ignition reading
^ Check B+ connection at alternator and battery terminal tightness.
^ Check UHJB 30 amp Ign 4, and five amp PCM 1 fuse.
^ Refer to "Starting and Charging Section" of the "Electrical Service Manual" for further diagnostics.