Hey everyone,

My sister has an 05 MCS (built 04/05) with about 45k on the clock.
About 3.5 weeks ago I had her car for a couple of days for maintenance
work. (oil change and brake pads) My dad and I took it to a local O'Reilly's to get the car battery checked and it said good-needs charging. So we put the car battery charger on it for a couple hours and it seemed good.

The next day the car went to a local mechanic to get new brake pads on it and we asked him if he would check the charging system....battery/alternator etc.

They said the car battery was kinda low and that the alternator was going bad. I told them that I thought the car was on it's original battery from the factory, so maybe the battery is making the alternator look bad.

So the day after that, I had an appointment with another mechanic to get a second option and to check some error codes as well...They suspected the same thing. After all of this happened, one week later we replaced the old factory battery with a brand new Duralast Gold (H5-DLG) then took it back to O'Reilly and they tested it and it said Good Battery and it was at a higher voltage and they tested the alternator and it was OK.

I saw the "Eli" (the car) and Haley yesterday (April 10) and she said the key fob remote does not work anymore on both keys.

I have read the key battery is suppose to charge in the ignition when on long trips, because there is no way you can open up the key to replace the battery. Could this be related in anyway to the alternator and the charging system or could the batteries in the key just died and I need to get different keys from the dealership?

I also read on a different thread on here that someone had to have rear view mirror replaced because mechanism to program the keys was in the mirror? The Rear View Mirror is a little wobbly and shakes like it going to pop off on every road bump. Or maybe the keys need just to get reinitialized?

Sorry for the long winded post, I thought telling the back story would help. Does anyone have any ideas what could be going on? Please reply.

Thanks!

 

Battery recharges on the 2005+ cars on longer trip....
If the battery was removed from the car for a long time, the remote might need to be "re-paired" to the cars remote door unlocking mechanism (the remotes).
The keys both have chips, one passive for antotheft, and the remote (unlocking, etc) that use the battery. There should be a post for re-pairing the remote to the car....just besure to use the right procedures....if i recall it is slightly different for the pre 2005 cars and 2005+ cars (when the keys became self charging). Google site search might be needed to get the right post if it has not been active in a couple years.
Replacement keys are very $$$, (about $150) and there are 2 steps with new keys...they must be paired with the antitheft (you do not need in your case as the keys are known to your car, and starts it fine) and the remote pairing (you need it redone). If the keys are charged, the re-pairing should take you just a few seconds. And just an hour or so of driving on each key a month should be enough to keep the batteries alive...heck my spare gets used 3-4 hrs a year, no issues.

 

Blueberry03MC:
Factory keys on the 05 MCS definitely charge themselves while in the ignition; no need to replace a battery.

Something similar happened with my key a few months ago. The remote functions on the key just stopped working; I couldn't pin down exactly what caused it (potential culprits were water on the key and the battery draining due to lights being left on, but I was never sure).

I tried a bunch of protocols that are supposed to re-program the key. I'm sure you've found them online: pressing buttons a certain number of times while opening and closing the door, etc. I tried numerous schemes like that, but to no avail; none of them ever worked.

Finally, I took the car to the dealer. The dealer rep took the key, sat inside my car with it for about 30 seconds, and then came back and said I was good to go. He reprogrammed the key and it has worked fine ever since. I don't know how he did it and he didn't charge me for it.

So I would suggest either continuing to try the various re-program schemes until you find one that actually works, or just take it into the dealer and have them do it.
MD

 

There are several reprogramming sequences? I have been able to find only (https://www.northamericanmotoring.co...n-r53-how.html) but it has not worked for me so far. Can you point in the direction of any other sequence we can follow to try to fix this issue.

By the way, I have a 2006 MC and until last night, I had no issue with the remote control function of my key. For some reason, that was not the case this morning.

 

If this doesn't work try your other key i tried over and over again and finally grabed my other key and got it to work the 1st time still cant get the 1st one to work but im okay with that for now

 

This happened to my 06 MCS.

I followed all of the reprogramming steps on both keys but still never got it to work.
I eventually brought it to the dealer and they determined it was a bad RF sensor in the car, which happens to be an auto-dimming & Homelink mirror too.

They quoted it as a $418 part and 30 hour worth of work. For now I'm just dealing with it. I've found the mirror online for $350, which isn't too much of a savings.

Hopefully yours just needs to be reprogrammed.
Mirror part #51169134363

 

Its almost been a year for this problem....the car has 61k on the clock now and we had to put this on the back burner because we had to get idler pulley harmonic balancer and the serpentine belt replaced. I have talked to the dealer about it and they said it could be the keys, the antenna, or the door latch itself. Nothing about the homelink mirror, which I think its the problem.
I live 3 hours away from the dealership its just finding the time to take it there sometime. I hope it just needs to be reprogrammed as well.

Hoonta- why would they charge for 30 hours worth of work? I too have searched online for a mirror and have not found anything cheaper than $350

 

My bad. Initially I was going to write .5 hours.
I meant 30 minutes.

 

I have the same problem.
Just stopped working after changing the battery and no reprogramming works

 

I suggest just taking it to the dealer. See my post above.

 

I bought new key from the dealer and they mailed it to me. Told me everything would work fine. Buttons don't. Dealer is three hours away.

 

By the way, I need a bad key that I can salvage a push-button out of. One of my buttons on the circuit board of my original key is bad.

 

A new key will start the car right away but the remote lock needs to be programmed. For '02-'04, the remote needs to be programmed by the dealer (some independent shops can also do it). For 2005 and newer, there is an initialization procedure you can do yourself: https://www.northamericanmotoring.co...ml#post1462932.

I owned a 2006 R52 for 9 years, and during that time my wife lost her keys twice. I bought a new key both times and the remote initialization worked perfectly. If the initialization isn't working, the problem could be in the car, not the key.