Multiplex Control System: Other Honda Pilot I рестайлинг

Multiplex Communication

To reduce the number of wire harnesses, digital signals are sent via shared multiplex communication lines rather than sending normal electrical signals through individual wires.

1. The input signals from each switch are converted to digital signals at the central processing unit (CPU). The digital signals are sent from the transmitter unit to the receiver unit as serial signals.
2. The transmitted signal is converted to a switch signal at the receiver unit, and it operates the related component.
3. There are exclusive communication lines between each of the multiplex control units: Door <--> Driver's (between the door and the driver's multiplex control units) wire color: BRN Driver's <--> Passenger's (between the driver's and the passenger's multiplex control units) wire color: PNK

The control units always communicate via these lines when the system is operating, and they stop communicating when the system is OFF.

Wake-up and Sleep

The multiplex control system has "wake-up" and "sleep" functions to decrease parasitic draw on the battery when the ignition switch is OFF.

1. In the sleep mode, the multiplex control unit stops the functions (communication and CPU control) when it is not necessary for the system to operate.
2. As soon as any operation is requested (for example, door is unlocked), the related control unit in the sleep mode immediately wakes up and begins to function. This control unit also sends a wake-up signal to the other control units via the communication lines.
3. When the ignition switch is turned OFF, and the driver's or front passenger's door is opened and closed, there is about a 15 second delay before the control units go from the wake-up mode to the sleep mode.
4. If any door is open, the sleep mode will not function.
5. If the key is in the ignition switch, the sleep mode will not function.
6. If a door or tailgate key cylinder switch is shorted, the sleep mode will not function.
7. When in the sleep mode, the current draw is reduced from 60-80 mA to less than 20 mA.

Fail-safe

To prevent improper operation, the multiplex control system has a fail-safe function. In the fail-safe mode, the output signal is fixed when any part of the system malfunctions (for example, a faulty control unit or communication line).

Each control unit has a hardware fail-safe function that fixes the output signal when there is any CPU malfunction, and a software fail-safe function that ignores the signal from the malfunctioning control unit and allows the rest of the system to operate normally.

Mode 1

Description

Mode 1 is a communication line and CPU self test. If a problem occurs on a communication wire or with an individual control unit the multiplex system will store a DTC as long as the fault is still present.

To Enter Mode 1

Scheme 6

Scheme 7

Scheme 8

Scheme 9

Scheme 10

Scheme 11

Scheme 12

Scheme 13

1. Check the No. 9 (10 A) fuse in the driver's under-dash fuse/relay box and the No. 13 (7.5 A) fuse in the passenger's under-dash fuse/relay box. Are the fuses OK? YES - Go to step 2. NO - Find and repair the cause of the blown fuse.
2. Connect the special tool to the multiplex control inspection connector (A).
3. Turn the ignition switch ON (II). If the driver's seat belt is unbuckled, the seat belt reminder will beep five times.
4. After about 5 seconds, the ignition key light should come on and the beeper should beep for 2 seconds, go off for 0.2 seconds, then blink and beep for 0.2 second. This means that you are in Mode 1 of the self-diagnosis function. Check self-diagnosis function Mode 1 for a diagnostic trouble code (DTC). MODE 1: Ignition Key Light and Beeper Did the multiplex system enter Mode 1 ? YES -Go to step 5. NO -Go to step 6 .
5. Check for a DTC. If there are no DTCs present: The ignition key light and beeper will not blink/beep again after the Mode 1 indication. If there is a DTC present: About 1 second after entering Mode 1, the ignition key light and beeper indicate the DTC(s), then repeat it every 3 seconds. If there is more than one DTC, the system will indicate them in succeeding order. Is there a DTC present? YES - Follow the procedure in the chart below. NO - Go to «MODE 2»(ref-243369-S19776385432006082300000) . DTC CHART DTC(s) Cause Procedure 1 The driver's unit is not able to receive signals from the door unit. Go to «BRN WIRE COMMUNICATION LINE TEST»(ref-243369-S22711352532006082300000) . 2 The driver's unit is not able to receive signals from the passenger's unit. Go to «PNK WIRE COMMUNICATION LINE TEST»(ref-243369-S01959167982006082300000) . 3 Malfunction in the driver's unit. Go to multiplex control system input test, if all inputs are OK, replace driver's multiplex control unit. 4 Signals from each unit do not match. Confirm correct multiplex control units are installed. 5 The passenger's unit is not able to receive signals from the other units. Go to multiplex control system input test, if all inputs are OK, replace passenger's multiplex control unit. 6 The door unit is not able to receive signals from the other units. Go to multiplex control system input test, if all inputs are OK, replace door multiplex control unit. 1,2 and 3 Simultaneously Communication (BRN or PNK) wire is shorted, (12 V or Ground). Go to «SHORTED COMMUNICATION LINE TEST»(ref-243369-S18940719792006082300000) .
6. Remove the special tool from the MPCS inspection connector.
7. Remove driver's multiplex control unit from the driver's under-dash fuse/relay box.
8. Check for voltage between the A24 terminal of the driver's under-dash fuse/relay box socket and body ground. Is there battery voltage? YES - Go to step 9. NO - Replace the driver's under-dash fuse/relay box.
9. Turn the ignition switch ON (II).
10. Check for voltage between A12 terminal of the driver's under-dash fuse/relay box socket and body ground. Is there battery voltage? YES - Go to step 11. NO - Repair an open in the wire between No. 13 (7.5 A) fuse in the passenger's under-dash fuse/relay box and driver's under-dash fuse/relay box socket.
11. Check for continuity between A14 terminal of the driver's under-dash fuse/relay box socket and body ground. Is there continuity? YES - Go to step 12. NO - Repair an open in the wire between driver's multiplex control unit connector and body ground. If the wire is OK, check for poor ground at G401.
12. Check for continuity between the B11 terminal of the driver's multiplex control unit connector and body ground. Is there continuity? YES - Go to step 13. NO - Repair an open in the wire between the driver's multiplex control unit connector and body ground. If the wire is OK, check for poor ground at G501.
13. Check for continuity between the No. 3 terminal of the MPCS inspection connector and the A15 terminal of the driver's under-dash fuse/relay box socket. Is there continuity? YES - Go to step 14. NO - Faulty driver's under-dash fuse/relay box internal circuit between the inspection connector and the driver's under-dash fuse/relay box. Replace the driver's under-dash fuse/relay box.
14. Check for continuity between the No. 1 terminal of the multiplex control inspection connector and body ground. Is there continuity? YES - If there is still no mode 1 indication, replace the driver's multiplex control unit and recheck the symptom. NO - Repair an open in the wire between the inspection connector and body ground. If the wire is OK, check for a poor ground at G401.

Mode 2

Description

Mode 2 is an easy way to identify a problem circuit with out having to test the circuit with a DVOM. Mode 2 will confirm a switch/circuit is working by flashing the ignition key light and sounding the beeper as the circuit is used. The multiplex control system will confirm inputs as they are grounded except for the following circuits

1. Turning the intermittent wiper ring (several confirmations as ring is turned).
2. Turning the dash light illumination dimmer (several confirmations as the knob is turned).
3. The Audio unit, Navigation display, RES display, DVD player (confirmation as any one component is disconnected).

To Enter Mode 2

Scheme 14

1. From Mode 1, disconnect the special tool from the multiplex control (MPCS) inspection connector for between 5 and 10 seconds, then reconnect it. The ignition key light should come on and the beeper should beep for 2 seconds, then blink/beep twice more at 0.2 second intervals. This indicates the system has entered Mode 2. Mode 2: Ignition Key Light and Beeper NOTE: To cancel Mode 2, disconnect the special tool from the multiplex control inspection connector for more than 10 seconds or turn the ignition switch OFF.
2. Operate the switches as described in the charts below. NOTE: A second key is necessary to test the key cylinder switches. If only one key is available, cut a second key from a non-immobilizer type key blank for the test. When testing the door lock knob switches, make sure all three passenger doors are locked. After unlocking the door, make sure to return the door lock knob switch to the lock position, otherwise the test results will be inaccurate. REFERENCE CHART Passenger's Multiplex Control Unit First start with the front passenger's door lock knob switch in the lock position Right rear door lock knob switch (UNLOCK) Front Passenger's key cylinder switch (UNLOCK) Front Passenger's door lock switch (LOCK/UNLOCK) Front Passenger's door switch (OPEN) Right rear door switch (OPEN) Rear window wiper switch (WASHER/WIPER/INT) Tailgate key cylinder (LOCK/UNLOCK) Security input for the radio, navigation system or, DVD player, or rear controller and screen. Test by disconnecting and reconnecting the radio, navigation system or, DVD player, or rear controller and screen connector. REFERENCE CHART (DRIVER'S MULTIPLEX CONTROL UNIT) Driver's Multiplex Control Unit Dash lights brightness controller (ROTATE) Driver's door switch (OPEN) Left rear door switch (OPEN) Left rear door lock knob switch (UNLOCK) Tailgate latch switch (OPEN) Driver's seat belt switch (UNBUCKLED) Windshield wiper/washer switch (except MIST switch) Brake pedal position switch (Brake switch) (PRESSED) Parking brake switch (ON) Hood switch (OPEN) Headlight or combination switch (ON) REFERENCE CHART (DOOR MULTIPLEX CONTROL UNIT) Door Multiplex Control Unit Driver's door lock knob switch (LOCK/UNLOCK) Driver's key cylinder switch (LOCK/UNLOCK) Driver's door lock switch (LOCK/UNLOCK) Driver's key cylinder switch (UNLOCK) Power window master switch (the passenger's switches) (UP/DOWN) Did the multiplex control system confirm all the circuits by flashing the ignition key light and sounding the beeper? YES - The multiplex system is OK, if the symptom is still present, go to the input test for the system with the problem (see chart below), or refer to Multiplex Control Unit Input Test (see «MULTIPLEX CONTROL UNIT INPUT TEST»(ref-243369-S26691960242006082300000) ). SYSTEM REFERENCE CHART System Power door locks (see «CONTROL UNIT INPUT TEST»(ref-243379-S21794352332006082300000) ) Security (see «CONTROL UNIT INPUT TEST»(ref-243379-S21794352332006082300000) ) Keyless (see «CONTROL UNIT INPUT TEST»(ref-243379-S21794352332006082300000) ) Power windows (Includes key-off timer operation) (see «CONTROL UNIT INPUT TEST»(ref-243312-S40374626862006082300000) ) Entry light control, Key light timer (see «CONTROL CIRCUIT INPUT TEST»(ref-243371-S32436512992006082300000) ) Wiper controls (front and rear) (see «CONTROL UNIT INPUT TEST»(ref-243349-S06021858322006082300000) ) Automatic lights off (see «AUTO-OFF HEADLIGHTS CONTROL UNIT INPUT TEST»(ref-243317-S03713234882006082300000) ) Reminder chimes (Key-in, seat belt, lights-on) (see «CONTROL UNIT INPUT TEST»(ref-243368-S02966173662006082300000) ) Low oil pressure indicator (see «CONTROL UNIT INPUT TEST»(ref-243368-S02966173662006082300000) ) NO - Find the open or short in the circuit that was not confirmed by the multiplex control system. If the circuit is OK, replace the multiplex control unit that monitors the circuit.

Scheme 15

1. Remove the driver's multiplex control unit from the driver's under-dash fuse/relay box.
2. Carefully pry off the driver's door switch trim (see «FRONT DOOR PANEL REMOVAL/INSTALLATION»(ref-243346-S33342185312006082300000) ).
3. Disconnect door multiplex connector A (20P).
4. Check for continuity between A2 terminal of the driver's under-dash fuse/relay box socket and No. 15 terminal of the door multiplex control unit connector A (20P). Is there continuity? YES - Replace the multiplex control unit most closely related to the failure. NO - Repair an open in the wire between the door multiplex connector and the driver's under-dash fuse/relay box. If the wire is OK, replace the driver's under-dash fuse/relay box.

Scheme 16

1. Disconnect driver's multiplex control unit connector B (22P).
2. Disconnect passenger's multiplex control unit connector B (22P).
3. Check for continuity between B1 terminal of the driver's multiplex connector B (22P) and B9 terminal of the passenger's multiplex connector B (22P). Is there continuity? YES - Replace the multiplex control unit most closely related to the failure. NO - Repair an open in the wire between the driver's multiplex control unit connector B (22P) and the passenger's multiplex control unit connector B (22P).

Scheme 17

Scheme 18

1. Remove the driver's multiplex control unit from the driver's under-dash fuse/relay box.
2. Carefully pry off the driver's door switch trim (see step 5 in «FRONT DOOR PANEL REMOVAL/INSTALLATION»(ref-243346-S33342185312006082300000) )
3. Disconnect door multiplex connector A (20P).
4. Disconnect passenger's multiplex control unit connector B (22P).
5. Check for continuity between No. 15 terminal of door multiplex connector A (20P) and body ground. Is there continuity? YES - Repair short to ground in the wire between door multiplex control unit connector and body ground. NO - Go to step 6.
6. Check for continuity between B9 terminal of passenger's multiplex connector B (22P) and body ground. Is there continuity? YES - Repair short to ground in the wire between passenger's multiplex control unit connector and driver's multiplex control unit connector. NO - Replace driver's multiplex control unit and recheck the symptom.