DTC P0646:00 [SKYACTIV-D 2.2]


id0102s4587900

DTC P0646:00

A/C relay circuit low input

DETECTION CONDITION
•  When the following conditions are met, PCM detects that the A/C relay voltage is approx. 0 V for a continuous 5 s:
MONITORING CONDITIONS
―  Battery voltage: 8—20 V
―  A/C relay controlled off
Diagnostic support note
•  This is a continuous monitor (other).
•  The check engine light does not illuminate.
•  FREEZE FRAME DATA (Mode 2)/Snapshot data is available.
•  DTC is not stored in the PCM memory.
FAIL-SAFE FUNCTION
Not applicable
POSSIBLE CAUSE
•  Front body control module (FBCM) DTC is stored
•  A/C relay malfunction
•  Front body control module (FBCM) connector or terminals malfunction
•  PCM connector or terminals malfunction
•  Short to ground in wiring harness between the following terminals:
―  Front body control module (FBCM) terminal 1C—A/C relay terminal A
―  A/C relay terminal E—PCM terminal 2BE
•  Front body control module (FBCM) malfunction
•  PCM malfunction

Diagnostic Procedure

STEP

INSPECTION

ACTION

1
VERIFY FREEZE FRAME DATA (MODE 2)/SNAPSHOT DATA HAS BEEN RECORDED
•  Has the FREEZE FRAME DATA (Mode 2)/snapshot data been recorded?
Yes
Go to the next step.
No
Record the FREEZE FRAME DATA (Mode 2)/snapshot data on the repair order, then go to the next step.
2
VERIFY RELATED SERVICE INFORMATION AVAILABILITY
•  Verify related Service Information availability.
•  Is any related Service Information available?
Yes
Perform repair or diagnosis according to the available Service Information.
•  If the vehicle is not repaired, go to the next step.
No
Go to the next step.
3
CONFIRM FRONT BODY CONTROL MODULE (FBCM) DTC
•  Perform the front body control module (FBCM) DTC inspection using the M-MDS.
•  Are any DTCs present?
Yes
Go to the applicable DTC inspection.
No
Go to the next step.
4
INSPECT A/C RELAY
•  Switch the ignition off.
•  Remove the A/C relay.
•  Inspect the A/C relay.
•  Is there any malfunction?
Yes
Replace the A/C relay, then go to Step 9.
No
Go to the next step.
5
INSPECT FRONT BODY CONTROL MODULE (FBCM) CONNECTOR CONDITION
•  Disconnect the front body control module (FBCM) connector.
•  Inspect for poor connection (such as damaged/pulled-out pins, corrosion).
•  Is there any malfunction?
Yes
Repair or replace the connector and/or terminals, then go to Step 9.
No
Go to the next step.
6
INSPECT PCM CONNECTOR CONDITION
•  Disconnect the PCM connector.
•  Inspect for poor connection (such as damaged/pulled-out pins, corrosion).
•  Is there any malfunction?
Yes
Repair or replace the connector and/or terminals, then go to Step 9.
No
Go to the next step.
7
INSPECT A/C RELAY CIRCUIT FOR SHORT TO GROUND
•  Verify that the A/C relay is removed.
•  Verify that the front body control module (FBCM) and PCM connectors are disconnected.
•  Inspect for continuity between the following terminals (wiring harness-side) and body ground:
―  A/C relay terminal A
―  A/C relay terminal E
•  Is there continuity?
Yes
Refer to the wiring diagram and verify whether or not there is a common connector between the following terminals:
•  Front body control module (FBCM) terminal 1C—A/C relay terminal A
•  A/C relay terminal E—PCM terminal 2BE
If there is a common connector:
•  Determine the malfunctioning part by inspecting the common connector and the terminal for corrosion, damage, or pin disconnection, and the common wiring harness for a short to ground.
•  Repair or replace the malfunctioning part.
If there is no common connector:
•  Repair or replace the wiring harness which has a short to ground.
Go to Step 9.
No
Go to the next step.
8
INSPECT FRONT BODY CONTROL MODULE (FBCM)
•  Inspect the front body control module (FBCM).
•  Is there any malfunction?
Yes
Replace the front body control module (FBCM), then go to the next step.
No
Go to the next step.
9
VERIFY DTC TROUBLESHOOTING COMPLETED
•  Always reconnect all disconnected connectors.
•  Clear the DTC from the PCM memory using the M-MDS.
•  Start the engine.
•  Turn the air conditioner on and off.
•  Perform the DTC Reading Procedure.
•  Is the same DTC present?
Yes
Repeat the inspection from Step 1.
•  If the malfunction recurs, replace the PCM.
Go to the next step.
No
Go to the next step.
10
VERIFY AFTER REPAIR PROCEDURE
•  Perform the “AFTER REPAIR PROCEDURE”.
•  Are any DTCs present?
Yes
Go to the applicable DTC inspection.
No
DTC troubleshooting completed.