Door Lock problem Honda Accord 2005
 

Hi,

I hope someone could point me in the right direction for troubleshooting a door lock issue I have:

My honda accord 2005 sedan v4 ex door lock system will not lock. I had some mechanics look at it but they said only the dealer can fix it, but they seemed to be confused when looking at the car so before going to the dealer here if what I have done:

Since the back doors unlock and don't lock I think the actuators are fine there but the driver's side door would not unlock or lock so I replace the actuator and it started to unlock again. When I say unlock I mean using the switch on the driver side door. The remote on the key unlocks the back doors and the driver's side door but it too doesn't lock them. By the way, I am ignoring the left side front door as it doesn't lock or unlock, I believe the actuator is bad there too but even if I replace it I still believe it won't solve the locking issue, so I want to leave that until the end.

I noticed that when I unlock the doors there's a small click on top of the fuse box under the dash and then the actuators take over and unlock the doors. When I lock the doors I hear the same small click on top of the fuse box but the actuators don't activate and hence don't lock the doors. It seems that electricity goes from the switch to the fuse box area but from there it doesn't go to the actuators. I noticed there's some relays on top of the fuse box but the manual doesn't even show these relays and I haven't found any manual online that shows what each of them do. I believe one of them might control the door locks and might be faulty. Am I in the right direction? I noticed in some door lock posts that a user said there's no relays involved in the door lock system, is this accurate?

I have read that for similar issues that grounding might be at fault but how can the actuators unlock fine if grounding is the issue? Is there any test I can do with a voltmeter? I tried to read voltage by setting the voltage to 20 and 2 but don't seem to get any readings when I press the switch to unlock or lock. I do get some very small readings when using 2 and unlocking but I also get the same readings by just touching the tips of the voltmeter prongs with my fingers so I don't know if I am using it right. Sorry for my ignorance if I am doing something totally dumb, it is my first time troubleshooting anything with a car.

Thank you in advance for any help you may provide.

It may be a problem with the Multiplex Integrated Control Unit (MICU), which is built into the under-dash fuse/relay box.

1. Do a battery cable reset by disconnecting the negative and positive cables and connecting them together with a jumper wire for 15 minutes. -- Do not touch the battery terminals.

2. If that doesn't work, the MICU may need replacement.

See this thread:
https://www.hondaaccordforum.com/for...k-doors-51779/

Another possibility is there is an open in the Yel/Blk wire that controls the lock function from the MICU to the respective actuators. But, usually the problem is related to the MICU.

HI,

Thanks for your feedback, after doing some googling I thought that the MICU was bad too but when I went to Pepboys and asked for the part they said what I am looking for is the Main relay and that I can only get it from the dealer. My mechanic didn't know what that is so I dropped that hunch. But since you mentioned it could you describe where it is on the car? I thought it would be one of the relays on top of the fuse box (under the dash) but none of the labels say MICU, can't find any pictures with google either just descriptions.

Thanks again for all your help.

That MICU is integrated into the fuse box. If it required replacement, the entire interior fuse box on the driver side is replaced. Only two bolts hold the fuse box in (one bolt at the bottom and one bolt at the top left of the fuse box). You have to transfer the relays and fuses to the new one. Honda does not recommend using pliers to remove the relays, as you can damage the relays that way.

Did you try the MICU reset procedure I posted above?

Thanks for the feedback,

I ran the reset procedure this morning but I still have the same issue but the reset seem to have fix the factory radio system as I could not input the code before but now when I input the code it took it and the radio works. But the doorlocks are still not locking.

One more thing that I forgot to mention is that as I am driving the actuators keep on unlocking themselves as if I was hitting the unlock switch.

thanks again for the feedback.

I called Honda to get a price for the MICU unit, they said they have never heard of this part. They gave me a price for the fuse box, is there another name that the MICU unit goes by? I want to make sure that I get the right part just the fuse box is over $200, does that sound right?

Reading this post: "BRAKE" light stays on dashboard,cruise,central lock,AC not working - Honda-Tech

found this honda parts site: Honda Automotive Parts

where they list the fuse box at $140, with this part number:

38200-SDA-A21 007 001 BOX ASSY., FUSE

from the image and what redbull-1 mentioned about the micu unit being intergrated into the fuse box I take it that the back part of the fuse box in the image is the micu, I will get it and install it and post back my results in case anyone is having similar issues, (the fuse box is number 7 below):

http://www.hondaautomotiveparts.com/...da01_b1310.png

Thanks for the assist Redbull-1.

I usually don't like to make recommendations to replace parts without proper testing; however, there is no easy way to test the MICU without the proper equipment and procedures; additionally, diagnostic at the dealer will not be cheap.

It does sound like it is related to the MICU though.

This service bulletin is for a V6 with a different fuse box part number since it is for a V6; however, I am posting it to give you the basic fuse box removal and installation instructions.

Honda TSB 03-029

There are some used fuse boxes on ebay; but, the ones I see don't necessarily list the part number used by your car model.

Good luck and let us know how it turns out.

door lock issue SOLVED!
 

Hi,

First - Thanks Redbull-1 for all your help. I was hesitant to replace the fusebox(MICUO unit because I had an aftermarket alarm for which I no longer had the remote control and I had taken out the fuse at the battery because it would arm itself and unlocking the door locks with the key wouldn't disarm it any more. This started to happen after the battery died and I got someone to jump start it.

Anyhow, I looked at the aftermarket alarm wiring and it looked too complicated to take out, it had wires connected to the fuse box so I wasn't sure the connectors had to be taken out or just cut the wires. I paid the dealer to do this for $220 and they verified that it was the MICU unit not working.

I bought the MICU unit for $140 and installed it myself with the instructions provided in the previous post. Dealer would do it for $640 including parts and labor. Took about 4 hours, the fusebox has some connectors on the back towards the top which are very hard to take out, I had to move the dash a little.

There's one problem, now the rear left door's window doesn't work, it won't go up or down. Honestly, I am going to leave it like that unless it is something easy. The switch on the left rear door doesn't control the window either so I hope it is not this MICU unit. I got it form majestic honda, I think they sell new stuff or maybe refurbish. Not sure.

Anyhow, I am good for now, thanks!!