Multiplex Intergrated Control System: Diagnosis Honda Element I

Troubleshooting

Special Tools Required

MPCS Service Connector 07WAZ-001010A

Scheme 4

Scheme 5

1. Check the No. 9 (10 A) fuse in the under-hood fuse/relay box and the No. 10 (7.5 A) fuse in the 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. Remove the driver's dashboard lower cover (see «DRIVER'S DASHBOARD LOWER COVER REMOVAL/INSTALLATION»(ref-220597-S27644829882006022100000) ).
3. Switch the ceiling light to the middle position. Close all doors. Turn the ignition switch ON (II). If the driver's seat belt is unbuckled, the beeper will beep five times.
4. Check self-diagnosis function Mode 1 for a diagnostic trouble code (DTC) by connecting the special tool (A) to the multiplex control inspection connector (B). After about 5 seconds, the ignition key light and ceiling light should come on for 2 seconds, go out, then blink once for 0.2 second. This means that you are in Mode 1 of the self-diagnosis function. NOTE: To cancel Mode 1, disconnect the MPCS service connector from the multiplex control inspection connector for more than 10 seconds or turn the ignition switch OFF. Did the blinking lights confirm that you are in Mode 1? YES - Count the blinks, then go to step 5. NO - See if the SCS circuit is working properly, then go to step 6.
5. Check for continuity between the connector J of under-dash fuse/relay box No. 4 terminal and body ground. Is there continuity? YES - Faulty under-dash fuse/relay box. Replace and check for DTCs. NO - Repair the open in the wire or poor ground (G301), and recheck for DTCs.
6. If there is a DTC, it will blink, pause, then repeat the DTC as long as the ignition switch is ON (II). Is there a repeating DTC? YES - Count the blinks, then go to step 7. NO - Go to step 8.
7. About 1 second after you go into self-diagnosis Mode 1, the ceiling light will indicate the DTC, and repeat it every 3 seconds. If there is more than one DTC, the system will indicate them in ascending order, beginning from the DTC with the lowest numerical value. Troubleshoot the DTCs as indicated: DTC 1, 2, and 3 (ECM/PCM P0600) simultaneously: Check for a short to body ground in the YEL wire between multiplex control unit terminal E10 and ECM/PCM terminal E13, in the WHT/GRN wire between multiplex control unit terminal K10 and gauge assembly terminal B10. If both wires are OK, substitute a known-good multiplex control unit, gauge assembly, and ECM/PCM one at a time, in that order, and recheck for the DTCs after each substitution. DTC 2 and 5 simultaneously: Check for an open in the YEL wire between multiplex control unit terminal E10 and ECM/PCM terminal E13, If the wire is OK, substitute a known-good multiplex control unit, gauge assembly, and ECM/PCM one at a time, in that order, and recheck for the DTCs after each substitution. DTC 1 and 6 simultaneously: Check for an open in the WHT/GRN wire between multiplex control unit terminal K10 and gauge assembly terminal B10, and (on '04-06 EX and '06 EX-P models) in the BLU/ORN wire between the keyless receiver unit terminal No. 2 and the multiplex control unit terminal K2. If the wire is OK, substitute a known-good multiplex control unit, gauge assembly, and ECM/PCM one at a time, in that order, and recheck for the DTCs after each substitution. DTC 1 only (no other DTCs present): Substitute a known-good gauge assembly and a multiplex control unit one at a time, in that order, and recheck for the DTC after each substitution. DTC 2 only (no other DTCs present): Substitute a known-good multiplex control unit and a ECM/PCM one at a time, in that order, and recheck for the DTC after each substitution. DTC 3 only (no other DTCs present): Substitute a known-good multiplex control unit, and recheck for the DTC. DTC 5 only (no other DTCs present): Substitute a known-good gauge assembly, and recheck for the DTC. DTC 6 only (no other DTCs present): Update the ECM/PCM if it does not have the latest software, or substitute a known-good ECM/PCM, then recheck (see «ECM/PCM UPDATING AND SUBSTITUTION FOR TESTING»(ref-220569-S23624043112006022000000) ). If the symptom/indication goes away with a known-good ECM/PCM, replace the original ECM/PCM. DIAGNOSIS TROUBLE CODE DTC Cause 1 The multiplex control unit cannot receive signals from the gauge assembly. 2 The multiplex control unit cannot receive signals from the ECM/PCM. 3 The multiplex control unit cannot receive signals from itself. 5 The gauge assembly cannot receive signals from multiplex control unit and the ECM/PCM. 6 The ECM/PCM cannot receive signals from multiplex control unit and the gauge assembly.
8. From Mode 1, disconnect the special tool from the multiplex control inspection connector for about 5 to 10 seconds, then reconnect it. The ceiling light should come on for 2 seconds, go out, then blink twice more at 0.2 second intervals. This means the system has gone from Mode 1 to Mode 2. MODE 2: NOTE: To cancel Mode 2, disconnect the SCS service connector from the multiplex control inspection connector for more than 10 seconds or turn the ignition switch OFF.
9. Look in the following table for the switches most closely related to the problem. While still in Mode 2, operate the switches. If the circuit is OK, the ceiling light should blink once. If the circuit is faulty, there will be no indication. In the table below is a list of circuits that can be checked in Mode 2. SWITCH CIRCUITS LIST Windshield washer switch (ON) Windshield wiper switch (INT) Windshield wiper motor (Auto stop) Driver's door switches (doors open, one at a time) Driver's rear door switches Passenger's door switches (doors open, one at a time) Passenger's rear door switches Hatch latch switch (hatch open) Tailgate latch switches (tailgate open) NOTE: For tailgate switches to work, hatch latch must be manually latched. Parking brake switch (ON) Driver's door lock switch (LOCK/UNLOCK) Driver's door lock knob switch (LOCK) Driver's seat belt switch (UNLATCH) A/C switch (ON, with fan switch ON) Combination light switch (parking lights ON) ECM/PCM communication line (disconnect and reconnect) Gauge assembly communication line (disconnect and reconnect) Brake pedal position switch (pedal pressed) Transmission range switch (P, R, D, 2, 1) NOTE: You can check the rear door switches individually if the others are latched. Does the ceiling light blink? YES - Go to Sleep and Wake-up Mode Test (see «SLEEP AND WAKE-UP MODE TEST»(ref-220634-S15101221692006022100000) ). NO - Go to step 10.
10. Check two or three other circuits listed in the chart. Does the ceiling light blink for each circuit? YES - The additional circuits are OK. Repair the short or open in the circuit that failed the test in step 9 . NO - Multiple failed circuits can mean that the control unit has failed without triggering a DTC. Test a few more circuits. If they also fail, test the multiplex control unit inputs (see «MULTIPLEX CONTROL UNIT INPUT TEST»(ref-220634-S03371156752006022100000) ). If all the input test are OK, substitute a known-good multiplex control unit, gauge assembly, or ECM/PCM, one at a time, then recheck. If the system works properly, the part that was substituted is faulty; replace it. If there is still a malfunction, substitute a known-good control unit for the next most likely faulty control unit, then recheck. If the system works properly, that control unit is faulty; replace it.

Sleep and Wake-up Mode Test

1. Shift to the sleep mode: Turn the ignition switch OFF, and remove the key. If the control unit receives no signals from the inputs listed, it will go into sleep mode in less than 40 seconds. SWITCHES AND INPUT SIGNALS Multiplex Control Unit No. 10 (7.5 A) under-dash fuse Headlight switch (parking lights position OFF) Driver's door switch (door closed) Passenger's door switches (doors closed) Hatch latch switch (hatch closed) Tailgate latch switch (tailgate closed)
2. Confirm the sleep mode: Check for voltage on the YEL or WHT/GRN wires. There should be battery voltage in the sleep mode. Check the parasitic draw at the battery while shifting into the sleep mode. Amperage should change from about 200 mA to less than 35 mA.
3. Shift to the wake up mode: When the ignition switch is turned ON (II), the multiplex control unit, gauge assembly, and ECM/PCM wake up at the same time without "talking" to each other through the communication lines. When any switch in the multiplex system is turned on, it wakes up its related control unit which, in turn, wakes up the other units. After confirming the sleep mode, look in the following table for the switch most closely related to the problem. Operate that switch and see if its control unit wakes up. NOTE: If any control unit is faulty and will not wake up, several circuits in the system will malfunction at the same time. In the table, the control unit is followed by a list of the switches and input signals that can wake it up. SWITCHES AND INPUT SIGNALS Multiplex Control Unit No. 10 (7.5 A) under-dash fuse Communication lines (ECM/PCM, keyless receiver unit ('04-06 EX and '06 EX-P models), and gauge assembly) Headlight switch (parking lights position ON) Driver's door switch (door open) Ignition key cylinder switch (key inserted or removed) Ignition switch (ON (II) position)

Multiplex Control Unit Input Test

Note. Before continuing with the multiplex control unit input test, do the multiplex troubleshooting (see TROUBLESHOOTING ).

Scheme 6

1. Remove the driver's dashboard lower cover (see «DRIVER'S DASHBOARD LOWER COVER REMOVAL/INSTAL»(ref-220597-S27644829882006022100000) ).
2. Disconnect the under-dash fuse/relay box connectors C, E, F, J, K, O, P, Q, X and Y. NOTE: All connectors are wire side of female terminals.
3. Inspect the connector and socket terminals to be sure they are all making good contact. If the terminals are bent, loose or corroded, repair them as necessary, and recheck the system. If the terminals look OK, go to step 4.
4. Reconnect the connectors to the under-dash fuse/relay box, and make these input tests at the appropriate connectors on the under-dash fuse/relay box. If any test indicates a problem, find and correct the cause, then recheck the system. If all the input tests prove OK, the multiplex control unit must be faulty, replace the under-dash fuse/relay box assembly. TROUBLESHOOTING Cavity Wire Test condition Test: Desired result Possible cause if result is not obtained J4 BLK Under all conditions Check for voltage to ground: There should be less than 1 V. Poor ground (G301) An open in the wire Y6 BLK Under all conditions Check for voltage to ground: There should be less than 1 V. Poor ground (G502) An open in the wire J2 WHT/RED Under all conditions Check for voltage to ground: There should be battery voltage. Blown No. 9 (10 A) fuse in the under-hood fuse/relay box An open in the wire Q3 GRN Driver's door open Check for voltage to ground: There should be less than 1 V. Faulty driver's door switch An open in the wire Driver's door closed Check for voltage to ground: There should be 5 V or more. Faulty driver's door switch Short to ground Q4 GRY/BLK Front passenger's door open Check for voltage to ground: There should be less than 1 V. Faulty front passenger's door switch An open in the wire Front passenger's door closed Check for voltage to ground: There should be 5 V or more. Faulty front passenger's door switch Short to ground Q2 GRN/WHT Rear door open Check for voltage to ground: There should be less than 1 V. Poor ground (G751, G771, G551, G553) Faulty rear door switch An open in the wire Rear door closed Check for voltage to ground: There should be 5 V or more. Faulty rear door switch Short to ground Q8 : C8 : F1 GRN/ORN GRN/RED Parking brake lever pulled Check for voltage to ground: There should be less than 1 V. Faulty parking brake switch An open in the wire Parking brake lever released Check for voltage to ground: There should be about 5 V or more. Faulty parking brake switch Short to ground Q5 BLU/RED Ignition switch ON (II), driver's seat belt is unbuckled. Check for voltage to ground: There should be less than 1 V. Faulty driver's seat belt switch Poor ground(G552) An open in the wire Ignition switch ON (II), driver's seat belt is buckled. Check for voltage to ground: There should be 5 V or more. Faulty driver's seat belt switch Short to ground P18 RED Hatch or tailgate open Check for voltage to ground: There should be less than 1 V. Faulty hatch latch or tailgate latch switch An open in the wire Hatch or tailgate closed Check for voltage to ground: There should be 5 V or more. Faulty hatch latch or tailgate latch switch Short to ground X5 RED/WHT Ignition key is in the ignition switch. Check for voltage to ground: There should be less than 1 V. Faulty ignition key switch Poor ground (G401) An open in the wire Ignition key is out of the ignition switch. Check for voltage to ground: There should be 5 V or more. Faulty ignition key switch Short to ground X8 WHT/BLK With all doors closed Attach to ground: The ignition key light should come on. Blown No. 3 (7.5 A) fuse in the under-hood fuse/relay box Faulty ignition key light (LED) An open in the wire O7 GRN/RED Ceiling light switch in the middle position, all doors closed Attach to ground: The front ceiling light should come on. Blown No. 3 (7.5 A) fuse in the under-hood fuse/relay box Faulty front ceiling light An open in the wire C11 BLU Under all conditions Attach to ground: Dash lights should come on. Blown No. 2 (15 A) fuse in the under-hood fuse/relay box Faulty taillight relay An open in the wire F8 GRN/RED Parking brake released, disconnect the brake fluid level switch 2P connector, and jump the GRN/RED and BLK wires. Check for voltage to ground: There should be less than 1 V. An open in the wire Parking brake released, brake fluid level switch connector disconnected, jumper wire removed. Check for voltage to ground: There should be 5 V or more. Short to ground E10 YEL All doors and tailgate closed, ignition key removed Check for voltage to ground: There should be battery voltage in the sleep mode and 3-7 volts when awake. An open or short in the wire K10 WHT/GRN K2 (1) BLU/ORN Under all conditions Check for continuity between the K2 terminal and the keyless receiver unit 5P connector No. 2 terminal. (Disconnect connector K and the 5P connector): There should be continuity. An open in the wire Y1 BRN/YEL ABS control unit-modulator disconnected Check for continuity between the Y1 terminal and the No. 13 terminal of the ABS modulator-control unit: There should be continuity. An open in the wire F9 BLU/WHT Air conditioning switch OFF Check for voltage to ground: There should be about 5 V or more. Short to ground (1) '04-06 EX and '06 EX-P models