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Power door locks suddenly not working

221K views 55 replies 37 participants last post by  stevem48a3 
#1 ·
So today I get home from work and in the usual routine I hit my lock button on my key and start walking away, only this time I noticed that my interior lights stayed on and didn't fade out. I walked back over to my car and hit the lock button again and still the lights stayed on. :scratch: Hmmmmm. I hit the unlock button and opened my door and then closed it again thinking maybe the door didn't shut all the way the first time. Well it wasn't that because once again the interior lights stayed on when I hit the lock button. I noticed that the door lock stems were not down as far as usual. In fact they barely moved when I hit the lock or unlock button inside the car, although they did move slightly, just not enough to lock and shut off the interior light.

I can manually lock/unlock the doors with the key in the drivers door key hole or by manually pushing the door lock stem down on either driver or passenger side door. All other electical seems fine and when I push the drivers side lock stem down the passenger side goes down as well. I checked fuse for the power locks in the interior fuse panel and it's totally fine. The driving lights and interior lights flash like they should when I hit the lock/unlock button on the key but again the locks are barely moving/working.

Does this sound like it's a power door lock actuator gone bad? If so how difficult is it to replace? I looked online and I can get it from a local Honda dealer for $38 and change, so not too expensive. I've never had a reason to take the door panel off so it'll be new for me (for this car anyway). Any pointers, opinions or help would be greatly appreiciated! For what it's worth it's a 2003 V6 Coupe 6spd.
 
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#40 ·
Hi,
I'm having same issue exactly like yours, I replaced driver door actuator but still the same. All 4 doors won't lock but unlocks fine.
Accordnewb: Are you having this identical issue of the doors unlocking OK but not locking? Is your dash light indicating a door ajar (make sure your bulb isn't burned out first)? Regardless, the condition above may happen if one of the door sensors is not recognizing the door(s) to be locked. Try removing the door sensors one at a time and clean out the contacts and see if the locks work.
 
#37 ·
This is a very old thread and I have not read through every single posting to see what has been said or done. My apologies. But I think I get the gist of your problem: doors unlock don't lock back up from the keyfob. Doors lock fine manually, and alarm can be armed via the keyfob after that. Is that correct?

For now I'm going to give you the basics...and I'm going to assume you checked the appropriate fuses (you'll have to research which ones they are), put new batteries in the keyfob, and, for good measure, re-programmed the keyfobs (easy to do yourself.) If you haven't, please do so and report back on your findings. Also check on your car battery status. Is it old? Any difficulties with car starting? A week battery can occasionally cause problems.

The driver's door actuator controls the others. If this actuator is sluggish or not working, the others may have difficulties--other locks may or may not work, or work intermittently. If this is the case, replace it. It's a very easy DIY and will cost about $20-35 off ebay or Amazon.

The driver's door also has what's called a "master switch". This is only under the driver's armrest control "switches". It has a small circuit board on the underside. You can remove the master control switch, have a look around for good contacts/wiring, and re-solder joints on the circuit board itself that may be going bad. Extreme heat and age can wear out the circuits/solder joints. Or, you can just replace the switch. I AM NOT SAYING the problem is your switch. 'Just giving you a bare-bone explanation.

OK, so there is also something called a multiplex control unit that controls a myriad of cabin functions, among which houses circuits for the door lock, unlock, and trunk features. I'm not sure where this is on your particular car (make, model please). It's usually behind the driver's or passenger side fuse box, accessed from under the dash or under and the glovebox. If you have a car manual look for the wiring to see where the lock/unlock/trunk feeds off. Don't worry about getting dizzy, just see which unit it is.

On this multiplex unit there are three relays that are soldered on. They are for, you guessed it, door lock, door unlock, and trunk release features. Has your unlock relay or the entire unit failed? Dunno. Apparently you can still manually lock and use the trunk feature. But the master switch circuit feeds the multiplex unit and vice versa. So the problem, if not the driver's door actuator, could be in either the master switch or the multiplex unit. Or the wiring in between, usually a more rare problem.

All three things I mentioned--driver's door actuator, master switch, and multiplex unit can be easily replaced in about twenty minutes time or less for each. (Or go to the dealer and have it done for $250 each.) But which one is at fault? I do not want you to go out and throw parts at your cars. I'm just saying these are generally three of the things that control your lock/unlock features that can go wrong. I won't talk about the wiring in between.

I'd start out with a new keyfob battery, and re-programming the keyfob(s). Inspect and report back on your driver's door actuator. If it's sluggish at all or intermittently flakes out on you, change it. It's cheap and easy. If it seems Ok, your multiplex control unit may be getting bad. But, I have read in the past the master switch might be at fault, too. The best way to test which one truly is at fault, and you will not like what I have to say, is to temporarily switch them out from a car that's working properly. Easier said than done. Chances that you know similar car owners might not be good. I have done this as I have nine Hondas in the family and four others I know. Or, you can order and replace them one at a time, and if it wasn't the problem, return it for the cost of extra shipping.

Go inside your car and click the unlock button and trunk releases on your keyfob. Listen closely and you can hear the click of the appropriate relay activating. Close the door if you haven't, and click the lock on your keyfob. Do you hear the relay on the multiplex unit clicking? Use the door control to lock. Do you hear it now? If you hear the relay and nothing is happening, troubleshoot or replace the master switch. This will also tell you where that unit is located. (My '98 is on the passenger side fuse box). Yours, I think, is behind the driver's fuse box.

I won't talk about a bad keyfob transmitter. But it's quite possible that could be failing as well. If you have more than one and they are all misbehaving with the unlock function, the transmitter is not the issue. But if you only have one, keep a failing transmitter in mind.

I think the multiplex unit on your car is called a "control unit (cabin)". Go to any of the major Honda dealer websites (Bernardiparts.com is just one) to see it.

I had a problem with passenger side multiplex (door lock/unlock issue) and I was able to re-solder some joints and it's been working pretty good for a year now. I have a long post on it if you ever want to take a peek.
 
#42 ·
I didn't want to type all this all over again. In your situation, try a couple of things:

1. Listen for both the lock and unlock relays to click as you press the keyfob, per the above. Are you hearing them? I am mostly interested if you're hearing the unlock relays. If no sound, your relays (probably the lock relay) on the muliplex unit may be faulty and that whole unit needs to be replaced. Easy $40 (used) project for you.

2. Carefully inspect your dome lighting and its operation. Play with the on/off positions. Is it functioning properly? Carefully inspect the bulb at night and see if it's fluttering at all. If bulb is out check its fuse or replace the bulb. Ugh duh. Report back. The dome light circuit may be tied into the door lock sensor, alarm, etc and may cause your condition. I don't know for sure until I can see an electrical diagram for your car. What's your year and model, anyway?

3. Check and clean every door sensor. Pull the grommet out to expose the plunger. Lightly spray with WD40 and work the plunger. Do all of them in this manner and test the locks. If still no improvement, remove the door sensors by removing the screw(s)--I'm not sure how they're secured--and clean the contacts. Be careful that the sensor don't fall in the door.

4. The door master switch is not the culprit; it mostly controls the windows. But wait, is your lock/unlock door switch contained in the master switch or is it separate? If together, remove the master switch and look at the lock/unlock portion of the switch. I believe you should be be to remove it. Carefully inspect the contacts and clean them out and see if your doors work. If your door lock/unlock switch is separate, remove that, check the wiring, and clean the contacts. Any improvement? There are voltage tests I can have you do but I'd much rather have a margarita right now rather than explain it to you.

I may be very busy the next few days in case I am slow in responding to any further questions. Please post your results, and include pictures so we can see (door switch, master door switch, door sensors, etc. ). Maybe other very knowledgeable users on this forum will chime in and have some other things for you to try.

All the best,
Smurf
 
#39 ·
Accord 4, were you ever able to get this solved?

I am now experiencing this exact problem. I replaced the driver's door actuator about a year ago (due to a different problem) so I doubt it's that, checked the fuse under the dash as well as, and tested my remote. I also tried disconnecting the battery per this bulletin (http://ww2.justanswer.com/uploads/thebesthonda/2010-12-30_020210_tsb_power_door_locks.pdf) which did not seem to help.

Any solutions??
 
#43 ·
Adding a post-script since I always appreciate it when people do that on these forums:

I ignored the issue for a couple of months until I finally got sick of it. So two weeks ago I bought a multiplex unit from a junkyard (about $65 all-in) and got my mechanic to put it in for about $100. Problem solved. Everything works now.

I initially dragged my feet (after seeing Smurf's response) because the part is more like $150 to $200 new; for anyone in this situation in the future, I'd recommend scouring car-part or eBay for the part. Note that there are a number of different variations of that control unit so I'd use a site like hondapartsnow (or Bernardiparts) to confirm the item #.

Thanks again to Smurf for the helpful feedback.
 
#44 ·
Power door dysfunctional

Hey Guys, I am one of the new Honda Users who drives an old Honda. Bought my 2003 Accord EX Coupe a few weeks ago from a dealer (while trying my best not to get ripped off) and managed to get a sort of a decent deal, but not without a few shortfalls. And one of them, you guessed it, is the door lock/unlock feature.
To begin with, let me tell you that the remote I got while purchasing the car looks like it has been punched in the face by an ace boxer. The remote at some point, used to have a key attached to it, which is not there now. Instead the previous owner must have gone to a local locksmith and made himself one of those cheap keys, without remote. The lock button on the remote doesn't work (Looks like there is glue under it and it is fixed). The door unlock and trunk buttons work though (by work I mean that they can be pressed. The trunk button works fine and thankfully so, because the trunk lever on the driver's side is dysfunctional- and that is a whole different issue). Here's my problem, in details.

I can press the door unlock switch and the driver's side door opens fine, but the passenger door doesn't. When I press the master key on either side, I can hear the relays clicking but none of the door opens or locks (except sometimes, when the driver door locks, but doesn't unlock unless I pull the little knob with my hand). Needless to say, with the condition of my remote, I cannot try to unlock the doors with it. However, the funny thing is that when I long press the remote unlock button, both the windows roll down smoothly. Also worth mentioning here is that my power windows work just fine. So, what I do is I unlock the driver's door with the remote and then go inside the car and manually unlock the other door. While locking the car, I have to lock both doors manually. Now, here are my questions.

1. Could it be a problem with the actuator on driver's side? I am really confused because the driver's door opens with the remote but the master switch does nothing to lock/unlock it.

2. Could it be a problem with the actuator on the passenger door? This is a possible source as the passenger door neither unlocks with the remote nor locks with the master switch, but this still doesn't explain my question 1.

3. Could it be a problem with the multiplex circuit board as mentioned in the previous posts.

Also, a little off topic but worth asking. Is it worth to buy a new remote from amazon (15-20 bucks), program it myself and then go to a locksmith to get it cut, will it start the car (the serial number on the back of my existing remote is illegible) or should I rather go to a Honda dealer and get a new key for 120 bucks?

Looking forward to some eye openers!
 
#45 ·
Adding details about my own experience...

2003 Accord EX V6 sedan. The power door locks stopped LOCKING a couple of weeks ago. All 4 doors would not lock via the key fob, the lock button on the front door armrests, or via the driver's door keyhole. All 4 doors would power unlock, but they would not lock. When you pressed the door lock button there was no sound of any kind.

The door open/closed switches seemed to be working okay. When you opened any door the dome lights would come on and the door ajar indicator on the instrument panel illuminated as expected.

I purchased a new interior fuse box and Multiplex Integrated Control Unit (MICU) (Honda Part # 38200-SDB-A21 -- for the 4-door SEDAN) from Bernardi Honda -- $159.38 plus shipping. I installed the new fuse box and that has resolved the problem with the doors not power locking.

It's my understanding there are 4 relays on the printed circuit board (PCB) on the MICU -- door lock, driver's door unlock, all 4 doors unlock, and trunk release. Apparently the door lock relay failed and since the relays are integrated onto the PCB you have to replace the entire unit when a relay fails.

Replacing the fuse box was not a fun job. Working under the dash is difficult and disconnecting the multitude of wire plugs from the fuse box was hard. In particular unplugging the ones on the back side of the fuse box was quite difficult. The wiring harnesses are tightly wrapped and tethered to the underside of the dashboard. The lack of free play in the wiring harnesses and tight space between plugs makes it hard to pull the plugs out of the sockets.
 

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#46 ·
Hey Smurf, if you're subscribed to this thread and happen to have the time, maybe you could help me with similar problems I'm having with my door locks, keyless entry, etc.

First I'll list each of the players in the chain and their respective functionality or issue whichever is more relevant.

Key fobs:
Both have quit working altogether.
No functionality/response from any component when pressing its corresponding button on the fob.
Replaced batteries in both fobs and verified their voltage via multimeter.
LED's work on both fobs.
Attempts to enter programming mode are futile as the fobs do nothing.

Door lock buttons:
Each works to lock/unlock a door.
Driver side power lock button will only lock all doors. will not unlock any doors and no sound is heard when attempting to unlock.
Pass door lock button functions normally.

Key lock cylinder:
All functionality using the key in the door including:
Locks all doors
Unlocks driver door on first turn
Unlocks remaining doors on second turn
All windows up/down

Other possibly related issues:
- When driver door is closed, the locks cycle twice but do not actually lock/unlock any door. You just hear the sound of the door lock actuators cycling twice.

- Doors have locked while engine was running and no one was in the car three times in the last couple of months.

- Driver window button auto up function works intermittently. It functions normally when not engaging the auto up/down feature.

- Unlocking the door with the key doesn't always deactivate the alarm. 3:10 times, after unlocking the door, the alarm sounds. can always immediately silence it using the key.


Have verified all fuses are good.

Does this sound like the MICU? I don't know how to t-shoot any further without an HDS to diagnose the B-CAN and/or pull any codes that might be present.

Any help with this will so very much appreciated! This is the wife's DD which translates to me hearing about it equally as often. :0:laugh

Coach
 
#48 ·
You've covered all the bases, as usual, Coach Steve!

Replace your MICU.

The relays are soldered and not replaceable. But it's not all about these relays... Several circuits (power windows, auto lock, dome light, climate control, etc.) flow through the MICU using the same electronics components, so if one or two bad components go bad (capacitor, resistor, transistors, etc.), it can effect one or more systems that are controlled by the MICU as you are experiencing. If you have the manual on your car look at the electrical section for the wiring diagram of the MICU just for fun.

Thanks, @BLCKFLSH on the diagnostics test on the other thread! (http://www.driveaccord.net/forums/15-7th-generation/399402-location-multiplexer.html#post5100354)
 
#49 · (Edited by Moderator)
If you have the manual on your car look at the electrical section for the wiring diagram of the MICU just for fun.
I'm afraid my head would explode if I did that.
Electrical wiring makes my mind go numb for some reason. I have to watch 2 or 3 YT videos and print out step-by-step directions just to wire a 3-way switch!! :yes: LOL! completely ,the opposite when it comes to wiring home theater, audio/video for large events, car stereo, etc. I guess it's because I love doing that stuff and I'm not intimidated by it like I am with electricity. Absolutely H A T E getting zapped!

Thanks for the verification on this. Now I won't feel like I'm rolling the dice, so to speak, by purchasing one. I hate, hate, hate throwing money at cars with fingers crossed and hope it solves the problem. I much prefer the process of elimination and isolating the responsible party.

If you were closer, I'd throw a nice detail on your car for you. But, you're not so I won't. :devil:laugh

Thanks again!

Check your other thread coach.
Just did, very cool! Thanks!

One last question..

Do I need to buy one specifically for my year and trim pkg. or will any 7th gen. MICU work?
 
#50 ·
I would just get the part number from any dealership website using your VIN, then google that number.
 
#51 ·
Got lucky by browsing Craigslist last night. Found a guy parting out his 2005 EX-L sedan with identical options. He just listed the car yesterday and had not sold anything off of it yet so the fuse panel is still there. And, since I'm having issues with the master power window switch, I'm going to get that from him as well. Total cost: $60.00 Niiiiiice!
The part I'm unclear about is the need for reprogramming the MICU. Does it need to be programmed to my car? If so, I'll have it done by one of the indy Honda repair shops that have an HDS machine rather than getting it done at the dealer. i just wish I could find the definitive answer about that. So far, no joy.

EDIT:
Was just thinking about this situation and realized if the vehicle requires reprogramming I won't be able to drive it to get it programmed. Apparently the immobilizer will interpret the new fuse panel as tampering and not allow the car to start. Additionally, the key will no longer be recognized. awesome!
It shouldn't be so freakin' hard to make your car work correctly when something the manufacturer installed fails!
 
#52 ·
Door lock button does not work on my 2003 Honda acccord

Hi I am having problems with my doors locking. I have a 2003 honda accord ex 4 door. My key remote stopped working totally and know i cant use the door lock buttons to lock my doors. I have to do it manually. But I dont think its the door actuator because if I manually lock all the doors. I can unlock them with the unlock buttons in the doors. But i cant lock the doors with the door lock buttons. I dont even hear a sound of the a door actuator trying to do any thing. I replaced the drivers door power window door master switch and this did not help. Help Please.
 
#54 ·
Hi I am having problems with my doors locking. I have a 2003 honda accord ex 4 door. My key remote stopped working totally and know i cant use the door lock buttons to lock my doors. I have to do it manually. But I dont think its the door actuator because if I manually lock all the doors. I can unlock them with the unlock buttons in the doors. But i cant lock the doors with the door lock buttons. I dont even hear a sound of the a door actuator trying to do any thing. I replaced the drivers door power window door master switch and this did not help. Help Please.
did anyone had sort this problem out
Replace the MICU.
 
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