DTC P1A18: Dc/Dc Converter 2 Boost Command Signal High: Notes

DTC detecting condition: 

Detected when two consecutive driving cycles with fault occur.

Trouble symptom: 

None

Wiring diagram: 

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

Courtesy of SUBARU OF AMERICA, INC.

1. CHECK DATA MONITOR  .
   1. Turn the ignition switch to ON.
   2. Read the data of [DC/DC Converter 2 Boost Signal Reception] using Subaru Select Monitor. Ref. to AUTO START STOP (DIAGNOSTICS)>DATA MONITOR .

   Is "ON" displayed in [DC/DC Converter 2 Boost Signal Reception]?

   Yes:  Go to  2.

   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  .
2. CHECK DC/DC CONVERTER 2 BOOST COMMAND SIGNAL  .
   1. Turn the ignition switch to OFF.
   2. Disconnect the DC/DC converter 2 connector.
   3. Turn the ignition switch to ON.
   4. Measure the voltage between DC/DC converter 2 connector and chassis ground.

      Connector & terminal 

      (B630) No. 3 (+) - Chassis ground (-):

   Is the voltage 5 V or more?

   Yes:  Go to  3.

   No:  Repair the poor contact o (DC/DC converter 2 connector. Replace the DC/DC converter 2 if defective. Ref. to STARTING/CHARGING SYSTEMS (H4DO)>AUTO START STOP DC/DC CONVERTER .

3. CHECK HARNESS BETWEEN ECM AND DC/DC CONVERTER 2  .
   1. Turn the ignition switch to OFF.
   2. Disconnect the ECM connector.
   3. Turn the ignition switch to ON.
   4. Measure the voltage between ECM connector and chassis ground.

      Connector & terminal 

      (B134) No. 7 (+) - Chassis ground (-):

   Is the voltage 5 V or more?

   Yes:  Repair the short circuit to power supply in harness between ECM and DC/DC converter 2.

   No:  Check for poor contact of ECM connector. Replace the ECM if no fault is found. Ref. to FUEL INJECTION (FUEL SYSTEMS) (H4DO)>ENGINE CONTROL MODULE (ECM) .