johnboy033

I apologize up front for the long post. I really need some help. My wife’s 99 Accord EX has intermittent power door lock and power window problems. Once every week or two, the car won’t unlock with the key fob (either fob). I unlock the car manually, it starts okay but the power locks and front windows don’t work from the driver’s armrest controls. I believe the back windows do work. Also, the locks don’t work from the passenger’s armrest control but the passenger’s window does work. They generally don’t work for about ten minutes then suddenly, everything is back to normal. It was merely an inconvenience until three weeks ago, while the locks and windows were not working; I tried this crazy sequence I found online to resets the multiplex unit (wipers on intermittent, turn key to on position, turn it off, blah, blah). When I did this, I could hear something clicking in the passenger side kick panel, and in concert with the clicking, the lights on the center consol were blinking. The clicking and blinking would not stop, even after I started the car. I played with it for a few minutes, repeating the steps until… the factory alarm starting sounding. I could not shut off the alarm because the key fob did not work (I ended up disconnecting the battery). The car was fine for a week then the next weekend, the locks stopped working; I opened the car with the key (like I’d done with no problems many times before) and then opened the passenger door for my wife and… the alarm started sounding. This time the locks started working rather soon after so I was able to shut the alarm off. I did not know at the time that you could deactivate the alarm by turning the key in the lock (if the key fob is not working) so I do not know if that would have turned off the alarm but, I had just entered the car using the key and the alarm sounded. I was also not paying attention to the security LED by the door **** (I inherited this car when I married my wife and still have a lot to learn about it). Anyway, we took it to Honda, they could not find anything wrong or replicate the problem (obviously). I need to fix this. Please help. Sorry again for the long post. Thanks.

hawkmgc

First off, honda shops love to say they can not find anything wrong as they know when it acts up again you will be right there to pay again.

here is a tech bulliton close to your issue:

Before diagnose a keyless entry problem on a 98-99 Accord EX, be aware that the keyless remote tramsmitters have a small battery contacts that can cause the transmitters to lose their memory if they're handled roughly. In other wards, don't drop them. If an Accord EX comes in with a trnsmitter problem, the first thing to do it make sure the transmitter's signal can be reconized by the passenger's multiplex control unit. To do this, resynchronize the transmitter.

To resync a trnasmitter, stand near the car, and press the transmitter's Lock or Unlock button six times. If the transmitter works after you resync it, let the customer know that banging it around or dropping it causes the problem.

Show your service advisors how to resync transmitters too. That way they can tell customers how to do it over the phone and prevent an unnecessary trip to the dealership.

Now this is a tech note to the dealerships.

Try this and if it still is buggy then you have a bad multiplex control unit.

johnboy033

Thanks for the reply. I can certainly try and see if that works but several things make me think it’s not the transmitters. When the locks go out, neither transmitter works. Also, the door lock switches on the door panels don’t work, and both front windows don’t work from the driver’s side controls. It's also intermittent, everything works fine 95% of the time. Unless I don’t understand how keyless entry works, the problem you describe sounds like a transmitter (not both at the same time) would cease working and not work again until it was resynchronized. That’s not the case here.

Are the keyless entry, power door locks, power windows, etc, all controlled by the passenger’s multiplex control unit? What does that unit cost, $100? I’m almost willing to just swap it for a new one to see if that works. Honda was nice enough not to charge me for the first visit. Thanks again for the input.

Rx7Rob

I had a similar problem on my dads 2002 Accord that I added an aftermarket remote starter / door locks.

The short version of the story is the door lock / unlock function stopped working. I traced the problem to the passengers side MPX control box. I opened the box and found a cold solder joint. After resoldering the unlock function returned. I didn't have time to trace down the lock problem.

I bet you have the same problem!