DTC P0A94: Dc/Dc Converter Performance: Notes

DTC detecting condition: 

Detected when two consecutive driving cycles with fault occur.

Trouble symptom: 

• Auto Start Stop does not operate.
• When the Auto Start Stop restarts, the audio or navigation system is reset.
• Power for audio and navigation system will not turn on.
• MFD does not operate.
• Doors cannot be opened/closed with keyless access system. (Vehicles with keyless access with push button start system)
• Illumination does not illuminate.
• Combination meter does not operate.
• A/C does not operate.
• VDC does not operate.
• EyeSight does not operate.

Wiring diagram: 

Auto Start Stop Ref. to WIRING SYSTEM>AUTO START STOP .

Courtesy of SUBARU OF AMERICA, INC.

1. CHECK VEHICLE CONDITION  .

   Turn the ignition switch to ON, and turn on the audio or navigation system.

   Is it powered on?

   Yes:  Go to  3.

   No:  Go to  2.

2. CHECK INPUT VOLTAGE OF DC/DC CONVERTER 1  .

   Measure the voltage between DC/DC converter 1 and chassis ground.

   Connector & terminal 

   (B563) No. 3 (+) - Chassis ground (-):

   (B563) No. 5 (+) - Chassis ground (-):

   Is the voltage 10 V or more?

   Yes:  Go to  3.

   No:  Check the following item and repair if necessary.

   • Open or short to ground in harness of power supply circuit
   • Blown out of fuse
3. CHECK REPEATABILITY  .
   1. Using the Subaru Select Monitor, perform the clear memory of [Transmission]. Ref. to COMMON (DIAGNOSTICS)>CLEAR MEMORY .
   2. Start the engine.
   3. Turn the ignition switch to OFF and wait for 10 seconds.
   4. Using the Subaru Select Monitor, read the DTC of [Transmission] after repeating the procedure from step  2 to  3 two times. Ref. to AUTO START STOP (DIAGNOSTICS)>DIAGNOSTIC TROUBLE CODE (DTC) .

   Is the same DTC as current diagnosis output?

   Yes:  Check for the poor contact of DC/DC converter 1 connector. Replace the DC/DC converter 1 if no fault is found. Ref. to STARTING/CHARGING SYSTEMS (H4DO)>AUTO START STOP DC/DC CONVERTER .

   No:  The circuit has returned to a normal condition at this time. Reproduce the failure, and then perform the diagnosis again.

   NOTE: In this case, temporary poor contact of connector, temporary open or short circuit of harness may be the cause  .