wraydp

I have a problem with my 2003 4-door Accord door locks not working properly. The remote key will unlock the doors, but not lock them. Even when using the interior door lock button on the door the doors will not lock, but they will unlock. I can manually lock them with the key though. This is the case for all 4 doors.

I ended up bringing my car into the Honda dealership and they hooked it up to their computer. They told me I need a new Multiplex unit and it would cost $400.00. Has anyone ever replaced one of these and how hard is it? Also, where can i buy one from?

MSchu

Any of the online dismantlers will have this unit at perhaps a 60-70% reduction in price. I am sure it is a bolt IN unit... so if you can screw bolts you should be okay.

Goev these guys a look, email him and ask, and if not there are many online parts houses. even your local napa may have the unit new(aftermarket)

Schu

http://cgi.ebay.com/ebaymotors...16811

Ch3mik

I had this issue for a week and then it went away.

vapor40

I have had to replace 2 of them. Not in my own car but at work. It's really the left underdash fusebox so it's not too hard to replace.

Good luck

phootbag

The doors won't lock with an open door. I'd make sure the door switches are functioning properly. They will unlock with an open door...

wraydp

Thanks for the replys.

Phootbag, The honda dealership hooked it up to their computer and they said it was the multiplex unit. But when I open the drivers side door, the indicator light on the dash does not show the door as being open. I can open any of the other 3 doors and the indicator light turns on showing the door open on the dash. This makes me think that the car thinks the door is not closed. Could the dealerships computer be wrong?

phootbag

It's possible they are correct. That car is a B-CAN car and they can see if there is a communication problem however I would think that multiple symptoms would be present if the entire multiplex unit wasn't communicating.

I'd check the door switch circuit before spending a few hundred bucks. It's a simple open/close switch. There is one wire. The switch grounds to the body. It's probably one of the easiest circuits to diagnose. You should see the switch in the door jam. It's got a little black rubber boot over it.

phootbag

By the way, their computer will never tell you what is wrong with a car. It just doesn't work that way.

wraydp

Thanks. How do I check the switch circuit if I don't have the proper tools? I'm not very good when it comes to electrical stuff.

phootbag

Remove the switch from the vehicle. When you unplug the switch be careful to NOT let the harness slip back into the hole in the vehicles body. Unplug the switch. Use a paper clip and carefully connect the terminal in the connector to a good body ground. The shiny door stiker next to the door switch works well. When you connect the terminal in the connector to the striker watch the indicator on the dash for a change. I cannot recall off the top of my head if the indicator comes on when you jump the terminal or not. Either way, look for a change in the indicator. Be careful when you use the paper clip not to damage the connectors terminal. I like using the metal part of the terminal from the BACK of the connector. Less risk of damaging the actual connection portion.

Pretty easy. Let me know what you find.