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

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.

•  The DTC is 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

•  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

•  PCM connector or terminals malfunction

•  Front body control module (FBCM) malfunction

•  PCM malfunction

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 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. • The DTC is 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 • 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 • PCM connector or terminals malfunction • 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.
1		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.
2		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. (See DTC INSPECTION [FRONT BODY CONTROL MODULE (FBCM)].) • Are any DTCs present?	Yes	Go to the applicable DTC inspection. (See DTC TABLE [FRONT BODY CONTROL MODULE (FBCM)].)
3		No	Go to the next step.
4	INSPECT A/C RELAY • Switch the ignition to off. • Remove the A/C relay. • Inspect the A/C relay. (See RELAY INSPECTION.) • Is there any malfunction?	Yes	Replace the A/C relay, then go to Step 9.
4		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.
5		No	Go to the next step.
6	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) connector is 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	If there is continuity between A/C relay terminal A and body ground: • Repair or replace the wiring harness between front body control module (FBCM) terminal 1C and A/C relay terminal A, then go to Step 9. If there is continuity between A/C relay terminal E and body ground: • If the short to ground circuit could be detected in the wiring harness: ― Repair or replace the wiring harness between A/C relay terminal E and PCM terminal 2BE. • If the short to ground circuit could not be detected in the wiring harness: ― Replace the PCM (short to ground in the PCM internal circuit). (See PCM REMOVAL/INSTALLATION [SKYACTIV-D 2.2].) • Go to Step 9.
6		No	Go to the next step.
7	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.
7		No	Go to the next step.
8	INSPECT FRONT BODY CONTROL MODULE (FBCM) • Inspect the front body control module (FBCM). (See FRONT BODY CONTROL MODULE (FBCM) INSPECTION.) • Is there any malfunction?	Yes	Replace the front body control module (FBCM), then go to the next step. (See FRONT BODY CONTROL MODULE (FBCM) REMOVAL/INSTALLATION.)
8		No	Go to the next step.
9	VERIFY DTC TROUBLESHOOTING COMPLETED • Make sure to reconnect all disconnected connectors. • Clear the DTC from the PCM memory using the M-MDS. (See AFTER REPAIR PROCEDURE [SKYACTIV-D 2.2].) • Start the engine. • Turn the air conditioner on and off. • Perform the DTC Reading Procedure. (See ON-BOARD DIAGNOSTIC TEST [SKYACTIV-D 2.2].) • Is the same DTC present?	Yes	Repeat the inspection from Step 1. • If the malfunction recurs, replace the PCM. (See PCM REMOVAL/INSTALLATION [SKYACTIV-D 2.2].) Go to the next step.
9		No	Go to the next step.
10	VERIFY AFTER REPAIR PROCEDURE • Perform the “AFTER REPAIR PROCEDURE”. (See AFTER REPAIR PROCEDURE [SKYACTIV-D 2.2].) • Are any DTCs present?	Yes	Go to the applicable DTC inspection. (See DTC TABLE [SKYACTIV-D 2.2].)
10		No	DTC troubleshooting completed.