Electrical equipment control system (MULTIPLEX) (Honda Civic 7)

Diagnostics

Reading fault codes (mode 1)

1. Check fuses #9 (10A) (mounting block in the engine compartment) and No.10 (7.5 A) (mounting block in the cabin).



2. Remove the lower instrument panel trim.

3. Turn the ignition switch to the ON (II) position.

4. Connect the special tool (B) to the diagnostic connector of the Multiplex control unit (A) and wait for 5 seconds or more.



5. Check that the interior light and local light blink as shown in the figure.

If the lamps do not flash, turn the ignition switch to the "OFF" position and repeat the procedure for reading fault codes starting from step "3"



6. Read the fault codes for the interior light and the local light. The fault codes are listed in the table "Electrical Equipment Management System Fault Codes".

Table. Electrical equipment control system fault codes.

Code	Malfunction
1	The Multiplex control unit does not receive a signal from the instrument cluster
2	The Multiplex control unit does not receive a signal from the powertrain control unit
3	Internal failure of the Multiplex control unit
5	The instrument cluster does not receive a signal from the Multiplex control unit and the powertrain control unit
6	The powertrain control unit does not receive a signal from the Multiplex control unit and instrument cluster

7. To exit mode 1, disconnect the special tool from the diagnostic connector of the Multiplex control unit and wait 10 seconds or turn the ignition switch to the "OFF" position.

Checking circuits to components (mode 2)

1. To switch to mode 2, while in mode 1, disconnect the special tool from the diagnostic connector of the Multiplex control unit for 10 seconds and reconnect it. Make sure that the interior light and local lighting lamp flash as shown in the figure.



2. The self-diagnostic system will check the circuits to the following components:

• driver seat belt sensor;
• pressure switch;
• central locking remote control unit;
• parking brake switch;
• "ABS" indicator;
• driver's door lock switch;
• electric windshield washer pump;
• windshield wiper motor;
• driver's door limit switch;
• front passenger door limit switch;
• rear left door limit switch;
• rear right door limit switch;
• key presence sensor in ignition switch;
• limit switch in the trunk lid lock (sedan);
• limit switch in the rear door lock (hatchback).

If the circuit is OK, the interior light will flash once.

If the circuit is faulty, the interior light will not flash.



3. To exit mode 2, disconnect the special tool from the diagnostic connector of the electrical equipment control unit and wait 10 seconds or turn the ignition switch to the "OFF" position.

Examination

1. Remove the lower instrument panel trim.

2. Disconnect the connectors.

3. Check fuses #10 (7.5A), #8 (7.5A) and #16 (20A) (mounting block in the engine compartment).

4. Check the electrical equipment control system according to the tables "Checking the electrical equipment control system".

Table. Checking the electrical equipment control system.

Conclusion	Wire color	Verification conditions	In good condition	Possible cause/location of malfunction
J2	W/R	Constantly	At the terminal "J2" the battery voltage	-Fuse No.9 (10 A) (mounting block in the engine compartment) -Broken wire
J4	IN	Constantly	Conductivity between terminal "J4" and ground	- Poor ground contact (G301) - Broken wire
Y6	IN	Constantly	Conductivity between terminal "Y6" and ground	-Bad ground contact (G501 *1 or G502²) - Wire break
Q3	G	The driver's door is open	Conductivity between terminal "Q3" and ground	- Driver's door limit switch - Wire break
Q4	Lg/R	The front passenger door is open	Conductivity between terminal "Q4" and ground	-Front passenger door switch -Wire break
Q2	G/W	Rear right or rear left door open	Conductivity between terminal "Q2" and ground	-Rear right or rear left door limit switch -Wire break
C8	G/R	Parking brake on	Conductivity between terminal "C8" and ground	-Parking brake position sensor -Wire break
F1	G/R		Conductivity between terminal "F1" and ground
Q6	BI/R	The driver's seat belt is not inserted into the buckle	Conductivity between terminal "Q5" and ground	-Bad ground connection (G551) -Driver seat belt sensor -Broken wire
R18	R	Trunk lid*1 or rear door 2 is open	Conductivity between terminal "P18" and ground	-Bad ground contact (G601*1 or G553²) Limit switch in trunk lid lock 1 - Limit switch in rear door lock 2 - Wire break
X5	R/W	The key is inserted into the ignition switch	Conductivity between terminal "X5" and ground	-Bad ground contact (G401) -Key in ignition switch sensor -Broken wire
07	G/R	Interior light switch in "MIDDIE" position	At the terminal "07" the battery voltage	-Fuse No.3 (7.5 A) (mounting block in the engine compartment) -Interior lighting lamp -Broken wire
C11	Bl	Light switch in the "ON" position	At the terminal "C11" the voltage of the battery	- Fuse No.2 (15 A) (mounting block in the engine compartment) - Side light relay - Light switch - Wire break
F8	G/R	Brake fluid level below the "MIN" mark	At the "F8" terminal the battery voltage	-Poor ground connection (G201) -Low brake fluid level sensor
Y1	Br/Y	Ignition switch in the "ON" position (II)	Conductivity between terminal "Y1" and ground	Wire break
E10*	Y	Constantly	At the "E10" terminal, the voltage is 3 - 8 V in "standby mode" or the battery voltage in "operating mode"	Wire break
K10*	W/G		At the "E10" terminal, the voltage is 3 - 8 V in "standby mode" or the battery voltage in "operating mode"	Wire break

• - connect the connector before testing,
• *1 - sedan,
• *2 - hatchback.

Table. Checking the electrical equipment control system (ignition key interlock system).

Conclusion	Wire color	Verification conditions	In good condition	Possible cause/location of malfunction
D10	BI/B	Automatic transmission selector in position "P"	Conductivity between pin "D10" and ground	-Bad ground contact (G101) -Automatic transmission selector position sensor -Broken wire
X1	W/R	Ignition switch in the "ACC" position	Conductivity between terminal "X1" and ground	- Poor ground contact (G401) - Broken wire

Table. Checking the electrical equipment control system (automatic transmission selector lock system).

Conclusion	Wire color	Verification conditions	In good condition	Possible cause/location of malfunction
E13*2	W/Y	Automatic transmission selector in position "P", ignition switch in position "ON" (II), brake pedal pressed	At the terminal "E13" the battery voltage	- Powertrain control unit - Wire break
O5	W/B	The brake pedal is pressed	At the "O5" terminal, the battery voltage	-Fuse No.7 (15 A) (mounting block in the engine compartment) - Brake light switch - Broken wire
D10	BI/B	Automatic transmission selector in position "P"	At the "D10" terminal the battery voltage	-Bad ground contact (G101) -Automatic transmission selector position sensor -Broken wire
G10	B/R	Automatic transmission selector in position "N"	Conductivity between the "GW" terminal and ground	-Bad ground contact (G101) -Automatic transmission selector position sensor -Broken wire
R3	Y/B	Ignition switch in the "ON" position (II)*1 or "ACC" (I)*2	At the "D4" terminal the battery voltage	-Fuse No.10 (7.5 A)*1 or No.8 (7.5 A) (mounting block in the cabin) - Selector lock solenoid valve - Wire break

• *1 - sedan
• *2 - hatchback.

Table. Checking the electrical equipment control system (central locking).

Conclusion	Wire color	Verification conditions	In good condition	Possible cause/location of malfunction
J7	W	Constantly	At the terminal "J7" the battery voltage	-Fuse No.16 (20 A) (mounting block in the engine compartment) -Broken wire
X5	R/W	The key is inserted into the ignition switch	Conductivity between terminal "X5" and ground	-Bad ground contact (G401) -Key in ignition switch sensor -Broken wire
Q3	G	The driver's door is open	Conductivity between terminal "Q3" and ground	- Driver's door limit switch - Wire break
Q4	Lg/R	The front passenger door is open	Conductivity between terminal "Q4" and ground	-Front passenger door limit switch -Wire break
Q2	G/W	Rear right or rear left door open	Conductivity between terminal "Q2" and ground	-Rear right or rear left door limit switch -Wire break
R18	R	Trunk lid 1 or rear door 2 is open	Conductivity between terminal "P18" and ground	-Bad ground contact (G601*1 or G553 *2) - Limit switch in the trunk lid lock 1 - Limit switch in the rear door lock 2 - Wire break
Y7	W/B	Driver's door lock switch in the "UNLOCK" position	Conductivity between terminal "Y7" and ground	-Bad ground connection (G501) -Driver's door lock switch -Broken wire
Y8	Y/R	Driver's door lock switch in the "LOCK" position	Conductivity between terminal "Y8" and ground
M6	Y/B	The battery is connected to terminals "M6" (+) and "M9" (-)	Driver's door lock is activated when battery is connected	- Driver's door lock electric drive - Wire break
M9	Y/B*1 Y*2
M7	Y/B	The battery is connected to terminals "M7" (+) and "M8" (-)	The front passenger door lock is activated when the battery is connected	- Electric drive of the front passenger door lock - Broken wire
M8	Y
R17	Y/B	The battery is connected to terminals "P17" (+) and "P16" (-)	Rear side door locks and rear door/trunk lid lock operate when battery is connected	- Electric drives of rear side door locks - Electric drive of trunk lid lock - Electric drive of rear door lock 2 - Wire break
R16	Y

• *1 - sedan
• *2 - hatchback.

Table. Checking the electrical equipment control system (interior lighting system).

Conclusion	Color - wires	Verification conditions	In good condition	Possible cause/location of malfunction
X5	R/W	The key is inserted into the ignition switch	Conductivity between terminal "X5" and ground	-Bad ground contact (G401) -Key in ignition switch sensor -Broken wire
Q3	G	The driver's door is open	Conductivity between terminal "Q3" and ground	- Driver's door limit switch - Wire break
Q4	Lg/R	The front passenger door is open	Conductivity between terminal "Q4" and ground	-Front passenger door limit switch -Wire break
Q2	G/W	Rear right or rear left door open	Conductivity between terminal "Q2" and ground	- Rear right or rear left door limit switch
R18	R	Trunk lid*1 or the back door *2 open	Conductivity between terminal "P18" and ground	-Bad ground contact (G601*1or G553 Limit switch in the trunk lid lock*1 - Limit switch in the rear door lock*2
Y8	Y/R	Driver's door lock switch in the "LOCK" position	Conductivity between terminal "Y8" and ground	-Bad ground connection (G501) -Driver's door lock switch
07	G/R	Interior light switch in "MIDDLE" position	At the terminal "07" the battery voltage	- Fuse No.3 (7.5 A) (mounting block in the engine compartment) - Interior lighting lamp

• *1 - sedan
• *2 - hatchback.

Table. Checking the electrical equipment control system (windshield wiper interval control system).

Conclusion	Wire color	Verification conditions	In good condition	Possible cause/location of malfunction
B1	W/BI	Ignition switch in the "ON" (II) position, windshield wiper switch in the "ON" position	At the terminal "B1" the battery voltage	-Fuse No.20 (20 A) (mounting block in the cabin) - Windshield wiper and washer control switch
X7	BI/B	Ignition switch in the "ON" (II) position, windshield wiper switch in the "INT" position	At the terminal "X7" the battery voltage	-Fuse No.20 (20 A) (mounting block in the cabin) -Windshield wiper and washer control switch
B6	BI/R	Ignition switch in the "ON" position (II)	At the terminal "B6" the voltage of the battery	-Fuse No.20 (20 A) (mounting block in the cabin) -Windshield wiper and washer control switch -Windshield wiper motor
G7	BI/W	Ignition switch in the "ON" position (II)	At the "G7" terminal, the battery voltage	-Fuse No.20 (20 A) (mounting block in the cabin) -Windshield wiper and washer control switch -Windshield wiper motor
X4	G/W	Rotate the wiper interval control	The resistance between terminals "X4" and "X3" varies within the range of 0-30 kOhm	- Windshield washer control switch - Wire break
I don't know	G/0

If a malfunction is detected, check the components listed in the "Possible Cause/Location of Malfunction" section of the table.

If the components are OK but the system does not work, replace the fuse box (in the passenger compartment) (electrical equipment control unit).