greeni70

I was wondering if anyone has had a similar problem: my 2001 Civic EX keyfob won't lock/unlock the doors. The lights will flash and horn will honk as it should, however the locking mechanism doesn't function as it should. Tried a new battery, but didn't help. I can hear the locking mechanism making a very slight noise when I push the button, and the power lock button on the inside of the driver's door does work fine. Doesn't make sense that if the power locks are working from the inside of the car, they wouldn't work from the keyfob. Any ideas? Thank you.

D Murphy

There is a separate keyless receiver unit under the middle part of the dash

Matt_75

You might want to check the fuses and cabling in the drawings below. You already know your horn works and driver door actuator works and the lights flash so you should be able to trace it from there. It still could be the keyless receiver unit as well.

If you think you'll need a keyless receiver unit it's piece #8 in the link below.

http://www.hondaautomotiveparts.com/...IT+%28CABIN%29

Also see below note out of service manual.

NOTE:

• If the doors unlock or lock with the transmitter, but the LED on the transmitter does not come on, the LED is faulty; replace the transmitter.
• If any door is open, you cannot lock the door with the transmitter.
• If you unlocked the doors with the transmitter, but do not open any of the doors within 30 seconds, the doors relock automatically.
• The doors do not lock or unlock with the transmitter if the ignition key is inserted in the ignition switch.

Using a keyless entry checker, (07MAJ-SP00300):
Put the transmitter (A) on the keyless entry checker (B) and press the button.

• If the ray indicator light (C) does not come on, check for:

• a dead or low battery.
• faulty transmitter.

• If the ray indicator light comes on, the transmitter is OK.

NOTE: When the transmitter battery was replaced, aim the transmitter at the receiver and press the transmitter button six times. The receiver is located behind the centre lower panel. Confirm you can hear the sound of the door lock actuators when you press the sixth time.

ezone

If there is zero response from anything when you use the fob, then look for a keyless issue.

OP says the lights flash and horn honks...I assume that is when the fob is used?
Can you link to the MICU self diagnostics pages?

Matt_75

Multiplex Control System

Troubleshooting

22-273


Special Tool Required: MPCS Service Connector 07WAZ-0010100

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 %u2013 Go to step 2.
NO %u2013 Find and repair the cause of the blown fuse.

1. Remove the dashboard lower cover (see page 20-75).
2. Turn the ignition switch ON (II).
3. 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 spotlight and ceiling light should come on then blink 0.2 second. This means that you are in Mode 1 of the self-diagnosis function.

1. 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 %u2013 Count the blinks, then go to step 8.
NO %u2013 See if the SCS circuit is working properly. Go to step 6.

1. Check for continuity between the inspection connector T1 and T3 terminals.

Is there continuity?
YES %u2013 Go to step 7.
NO %u2013 Faulty under-dash fuse/relay box, replace it and recheck for DTCs.

1. Check for continuity between the connector J of under - dash fuse/relay box No. 4 terminal and body ground.

Is there continuity?
YES %u2013 Go to step 9.
NO %u2013 Repair the open in the wire and recheck for DTC's.

Multiplex Control System

Troubleshooting (cont'd)

22-274

1. 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 below:

• 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 E24 and in the WHT/GRN wire between multiplex control unit terminal K10 and gauge assembly terminal A2. 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 E24, 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 DTC's 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 A2, 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 DTC's after each substitution.
• DTC 1 only (no other DTC's present): Substitute a known-good multiplex control unit and a gauge assembly one at a time, in that order and recheck for the DTC's after each substitution.
• DTC 2 only (no other DTC's present): Substitute a known-good multiplex control unit and a ECM/PCM one at a time, in that order and recheck for the DTCs after each substitution.
• DTC 3 only (no other DTC's present): Substitute a known-good multiplex control unit and recheck for the DTC.
• DTC 5 only (no other DTC's present): Substitute a known-good gauge assembly and recheck for the DTC.

• DTC 6 only (no other DTC's present): Substitute a known-good ECM/PCM and recheck for the DTC.

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. 4 The gauge assembly cannot receive signals from multiplex control unit and the ECM/PCM. 5 The ECM/PCM cannot receive signals from multiplex control unit and the gauge assembly.

Multiplex Control System

Troubleshooting (cont'd)

22-275

1. From Mode 1, disconnect the special tool from the multiplex control inspection connector for about 10 seconds, then reconnect it. The spotlight and ceiling light should come on for 2 seconds, then blink twice more at 0.2 seconds 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.

1. Look in the following table for the switches most closely related to the problem. While still in Mode 2, operate the switches and the control unit. If the circuit is OK, the spotlight and ceiling light should blink once. If the circuit is faulty, there will be no indication.

Does the spotlight and ceiling light blink?
YES %u2013 Go to step 12.
NO %u2013 Go to step 11.
In each table below is a list of circuits that can be checked in Mode 2.
Taillight relay Windshield washer motor
Windshield wiper motor (INT, Auto stop)
Driver's door switch
Front passenger's door switch
Left rear door switch
Right rear door switch
Ignition key switch
Trunk/Tailgate latch switch
Parking brake switch
Driver's door lock switch (LOCK/UNLOCK)
Passenger's door lock switch (LOCK/UNLOCK)
Driver's door key cylinder switch (LOCK/UNLOCK)
Driver's door lock switch (LOCK/UNLOCK)
Front passenger's door key cylinder switch (LOCK/UNLOCK)
Driver's seat belt switch (UNLATCH)
A/C switch (with fan switch ON)
Combination light switch
Keyless signal line
ECM/PCM communication line
Gauge assembly communication line
ABS communication
Front fog light switch
Tailgate key cylinder switch (LOCK/UNLOCK) (5 - door)

1. Check two or three other circuits listed above.

Does the spotlight and ceiling light blink for each circuit?
YES %u2013 The additional circuits are OK. Repair the short or open in the circuit that failed the test in step 10.
NO %u2013 Multiplex failed circuits can mean that the control unit has failed, but without triggering a DTC. Test a few more circuits. If they also fail, test the multiplex control unit inputs (see page 22-277). If all the input test are OK, substitute a known-good control unit, gauge assembly, or ECM/PCM, one at a time, then recheck. If the system works properly, the original control unit 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.


Multiplex Control System

Troubleshooting (cont'd)

22-276

1. Shift to the sleep mode:
   Turn the ignition switch OFF.
   If the control unit receivers no inputs from the inputs listed below, it will go into the sleep mode after about 20 seconds.

Multiplex Control Unit Taillight relay Driver's door switch
Front passenger's door switch
Left rear door switch
Right rear door switch
Tailgate latch switch (5-door)
Trunk latch switch
Driver's door key cylinder switch (LOCK/UNLOCK)
Driver's door lock switch (LOCK/UNLOCK)
Passenger's door lock switch (LOCK/UNLOCK)
Keyless communication line

1. Confirm the sleep mode:
   Check for voltage on the YEL and 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 70 through 80 mA to less than 10 mA.

1. 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 parts of the system will malfunction at the same time.
In the table below, the control unit is followed by a list of the switches and input signals that can wake it up.
Multiplex Control Unit No. 9 (10 A) under - hood fuse Communication lines (ECM/PCM, Gauge assembly) Taillight relay Driver's door switch
Front passenger's door switch
Left rear door switch
Right rear door switch
Driver's door key cylinder switch (LOCK/UNLOCK)
Driver's door lock **** switch (LOCK/UNLOCK)
Driver's door lock switch (LOCK/UNLOCK)
Tailgate key cylinder switch (LOCK/UNLOCK) (5 - door)
Front passenger's door key cylinder switch (UNLOCK)
Keyless communication line
Ignition key switch

Is the wake-up function OK?
YES %u2013 Intermittent failure; the system is OK at this time.
NO %u2013 Test the multiplex control unit inputs (see page 22-277).



Multiplex Control System

Multiplex Control Unit Input Test

22-277

1. Remove the dashboard lower cover (see page 20-78).
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. CONNECTOR C (14P) CONNECTOR E (13P) CONNECTOR F (12P) CONNECTOR J (8P)

CONNECTOR K (17P) CONNECTOR O (12P) CONNECTOR P (18P)

CONNECTOR Q (8P) CONNECTOR X (8P) CONNECTOR Y (13P)

1. 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.

Multiplex Control System

Multiplex Control Unit Input Test (cont'd)

22-278

1. With the connectors still disconnected, make these input tests at the connector.

• If any test indicates a problem, find and correct the cause, then recheck the system.
• If all the input tests prove OK, go to step 5.

Cavity Wire Test condition Test: Desired result Possible cause if result is not obtained

J4 BLK Under all conditions Check for continuity to ground: There should be continuity.

• Poor ground (G301)
• An open in the wire

Y6 BLK Under all conditions Check for continuity to ground: There should be continuity.

• Poor ground (G501)
• An open in the wire

Y1 BLK Under all conditions Check for continuity to ground: There should be continuity.

• 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 (10A) fuse in the under-hood fuse/relay box
• An open in the wire

1. Reconnect the connectors to the under - dash fuse/relay box and make sure 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.

Cavity Wire Test condition Test: Desired result Possible cause if result is not obtained

Q3 GRN Driver's door open Check for voltage to ground: There should be 1 V or less.

• 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 LT GRN/RED Front passenger's door open Check for voltage to ground: There should be 1 V or less.

• 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 Left or right rear door open Check for voltage to ground: There should be 1 V or less.

• Faulty rear door switch
• An open in the wire

Left or right rear door closed Check for voltage to ground: There should be 5 V or more.

• Faulty rear door switch
• Short to ground

Q8 %u00B7
C8
%u00B7
F1
GRN/ORN %u00B7
GRN/RED
Parking brake lever up Check for voltage to ground: There should be 1 V or less.

• Faulty parking brake switch
• An open in the wire

Parking brake lever up Check for voltage to ground: There should be 5 V or more.

• Faulty parking brake switch
• Short to ground

Q5 BLU/RED Ignition switch ON (II) driver's seat belt unbuckled. Check for voltage to ground: There should be 1 V or less.

• Faulty driver's seat belt switch
• Poor ground (G551)
• An open in the wire

Q6 BLU/RED P18 RED Trunk lid [tailgate] open Check for voltage to ground: There should be 1 V or less.

• Faulty trunk[tailgate]latch switch
• Poor ground (G601)
• An open in the wire

Trunk lid closed Check for voltage to ground: There should be 5 V or more.

• Faulty trunk[tailgate]latch switch
• Short to ground

X5 RED/WHT Ignition key is in the ignition switch Check for voltage to ground: There should be 1 V or less.

• 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

[ ]: 5-door




22-279

Cavity Wire Test condition Test: Desired result Possible cause if result is not obtained X8 WHT/BLK Under all conditions Attach to ground: The ignition key light should come on.

• Blown No. 3 (7.5A) fuse in the under-hood fuse/relay box
• Blown LED
• An open in the wire

O7 GRN/RED Ceiling light, spotlights switches in the middle position Attach to ground: The ceiling light, spotlights should come on.

• Blown No. 3 (7.5A) fuse in the under-hood fuse/relay box
• Faulty ceiling light or spotlights
• An open in the wire

C11 BLU Under all conditions Attach to ground: Dash lights should come on.

• Blown No. 2 (15A) fuse in the under-hood fuse/relay box
• Faulty taillight relay
• An open in the wire

F8 GRN/RED Brake fluid reservoir float in down position Check for voltage to ground: There should be battery voltage.

• Faulty brake fluid level switch
• An open in the wire

E10 YEL Under all conditions Check for voltage to ground: there should be 3 - 8 volts in the sleep mode and battery voltage when awake.

• An open or short in the wire

K10 WHT/GRN Under all conditions Check for voltage to ground: There should be 3 - 8 volts in the sleep mode and battery voltage when awake.

• An open or short in the wire

greeni70

Thanks for the responses guys, and all the great info! Yes, the lights flash, and horn honks when pressing the lock button on the keyfob. It sounds like the locking mechanism tries to work when I press the unlock button, but very faintly. Wouldn't a short of some kind prevent it from moving at all?

ezone

So it only makes a faint noise when you use the remote fob, but actually works correctly when you use the power lock switch on the door panel?

If it works from the switch on the door panel, will it operate more than twice in a row? (motors get weak when they get old....work for a couple seconds, then have to cool down before it works again).

greeni70

Yes that's correct. It seems to work perfectly from the power lock button on the door. Sounds like something is stuck or it's just getting very little power when pressing the unlock button on the keyfob, which is why I thought a new battery for the keyfob might fix it, but no luck.

ezone

This tells me that the fob works, and the receiver works.

SWAGs:
I would first make certain that the key warning beeper switch in the ignition housing isn't stuck on. (That would disable all remote functions.) Wait....that would keep the lights and horn from working too....
Same for the key cylinder switches in each door (built into the lock actuator, the 3 wire connector).
In my mind, I can see any of these above causing a disable or override of the remote functions.

Then maybe confirm powers and grounds present (or not) when remotes are activated, tested at the power lock actuator. If voltage is actually present but insufficient, that points toward the MICU.
Next steps would be testing the MICU (multiplex system) as outlined in the charts above.

Then decide what's next.

greeni70

So I took a closer look at what's going on, and the remote will lock/unlock the passenger side, but not at all times. It won't lock/unlock the driver's side at all. Is there some kind of trick I'm missing here? I know that the driver's side handle has to be pulled out for the switch to be pushed down manually, but there seems to be something wrong here. Unless there is some sort of trick to it and I'm activating a safety lock-out feature that I'm unaware of? It seems like the passenger's side lock will operate with the keyfob when I've unlocked it from the key on the driver's side, if I remember correctly. Is there a separate fuse for the driver's side lock?

ezone

That's correct. The passengers door cannot be unlocked until the MICU sees that the drivers door is unlocked.

I'll ask this again: Does the power lock switch on the drivers door operate all the power locks properly?

greeni70

I see. It does operate the passenger side. I'll have to check tomorrow to confirm, but I'm thinking that it does not operate the driver's side.

greeni70

Just checked it, and the power lock switch on the drivers side does not operate the lock/unlock on the drivers side. Its a coupe.

CraigW

iTrader: (1)

I think you have a failing drivers side actuator, The pulse used for keyless is very short and will make them show problems more easily.

scrapdog2grand

CraigW is correct, you need a drivers door lock actuator.
They go bad all the time.
the other side will go as well.
seen 3 out of 4 bad at one time on the 4 doors, a couple times.

civic1316

hi just wondering where did you connect your central locking?