Remote Lock/Unlock Intermittenly Not Working

[floridarunner]

I have had the same problem with our 2007 S60. It can be reset by alternately locking and unlocking the driver's door with the engine running. Sometimes it takes 3 tries while it may take 10 tries the next time. Since our mirror has a compass direction in one corner we can tell when it is working when it shows in the mirror. After many months of doing this we have determined that it works better in hot weather than on cold days. Someone on another forum traced it down to a "crystal" on a circuit in the UEM (inside rear view mirror). I think it could also be a bad solder connection in the UEM. We have decided to try the XeMODeX solution that works most of the time and seems to depend on getting a good used mirror to send to them along with your defective UEM. The cost is $250 plus the used UEM (which may or may not be good). Since you have to disconnect your battery before your remove the UEM and leave it unconnected until it comes back from XeMODeX you'll need to pick a time when you won't need to use the car for a few days. If you send it on Monday it should be back by Wednesday or Thursday. XeMODeX will send you a list of places where you can buy a used mirror for less than $100 including shipping. I'll update this when we get our mirror back. Our problem now is to find a time when we can go without the car for 3-4 days....

[abscate]

This thread has a lot of mixed up info between P2 and P3 chassis so if you are here trying to sort out a problem read carefully. Better yet, start a new thread, with title

Year Model symptom

To stop the thread mix problem

[firstv70volvo]

I have had the same problem with our 2007 S60. It can be reset by alternately locking and unlocking the driver's door with the engine running. Sometimes it takes 3 tries while it may take 10 tries the next time. Since our mirror has a compass direction in one corner we can tell when it is working when it shows in the mirror. After many months of doing this we have determined that it works better in hot weather than on cold days. Someone on another forum traced it down to a "crystal" on a circuit in the UEM (inside rear view mirror). I think it could also be a bad solder connection in the UEM. We have decided to try the XeMODeX solution that works most of the time and seems to depend on getting a good used mirror to send to them along with your defective UEM. The cost is $250 plus the used UEM (which may or may not be good). Since you have to disconnect your battery before your remove the UEM and leave it unconnected until it comes back from XeMODeX you'll need to pick a time when you won't need to use the car for a few days. If you send it on Monday it should be back by Wednesday or Thursday. XeMODeX will send you a list of places where you can buy a used mirror for less than $100 including shipping. I'll update this when we get our mirror back. Our problem now is to find a time when we can go without the car for 3-4 days....

I had the "crystal" problem and the symptoms were that my remote worked better in cooler weather, when hot it became intermittent but it could also be the other way around since it's likely a change in frequency over temperature that's causing the problem. Same symptoms with both key fobs because it's the receiver in the car that's the problem. The crystal device is on a vertical circuit board (see photo) in the rear view mirror and the one good thing about this is the small circuit board can be replaced without the need for programming the UEM at the dealer. The downside it is not an easy DIY job due to the soldering skills needed to remove and replace the circuit board but it can be done. You do need a used mirror for the donor board and and as I recall it doesn't have to be an auto dimming mirror either. Xemodex probably does this same repair.

I remember taking my car to the dealer for this problem and they couldn't even narrow it down to the CEM or UEM, which are both expensive items to replace, plus programming.