Key FOB Not Working When Car Has Been Sitting In The Sun

[MLPVT]

I have been experiencing a strange phenomenon with the power lock mechanism that only occurs when the car is in direct sunlight and hot to the touch (April - mid October).

Whenever my car has been sitting in the sun for at least one hour (and hot to the touch) and the air temperature is at least 50°F or higher, my key FOB's will refuse to lock or unlock the doors. However, when the sun goes down and the car cools off, or if I should move the car into the shade and allow it to cool, my key FOB works just fine. This happens day in and day out from mid April to around mid October when the intensity of the sun diminishes considerably.

I have never experienced a problem on heavily overcast days regardless of the ambient temperature. That leads me to believe the culprit is the mechanism which receives the RF signals from the key FOB.

I have replaced the batteries in both key FOB's so I know for a fact that is not the problem. Plus, I have only used one of the two FOB's exclusively since I purchased the car on November 30, 2004. The other key FOB was removed from the package for the very first time a few days ago when this phenomenon manifested itself for the first time this season.

My car is still under warranty, however, when I approached the dealership about this problem a few days ago, I got the distinct impression they are going to try once again to blame it upon the AstroStart Remote Starter which has nothing to do with the key FOB receiver.

Has anyone else experienced this problem?

Thanks in advance

[Bilby]

Dear Friend,
I had this problem with my 2001 XC also. I purchased the vehicle used in 2005 with a 2 year warranty. The problem started late in the first year of ownership. Because I live about 380 km from the dealership where I had the vehicle serviced - this ongoing problem would not present itself on the days when I had it down for service due to - cooler days or them not being able to park it in the sun for the period required. I was treated with some odd looks when I would explain that the vehicle had to be parked in the sun for at least an hour or two before the problem would arise. They often suggested that I purchase a new remote just to see if it would work better!? I declined..... One time it did actually play up while at the dealership and they said they fixed it by making an adjustment. Well I went home (380km away) and it was no different! Finally after the warranty had run out, they found the fault was with the Upper Electronic Module which apparently is in the rear view mirror (needed replacement)! The whole mirror had to be replaced and had to be ordered from Sweden - took about 3 months and cost me $521.50 for the mirror, $42.70 for the UEM reload, and $91.35 labour. By this time I was very fed up and just pleased to have it fixed, but I do feel they could have done more during the warranty period. The guys at the dealership said they tried to get VOLVO to cover this as it was a reported fault during the warranty period but they would not cover it. I have had no trouble since this was replaced (Dec 2007). I hope this will help you get your UEM looked at as the faulty part. Sorry for the long post too.
Best of luck,

[MLPVT]

Dear Friend,
I had this problem with my 2001 XC also. I purchased the vehicle used in 2005 with a 2 year warranty. The problem started late in the first year of ownership. Because I live about 380 km from the dealership where I had the vehicle serviced - this ongoing problem would not present itself on the days when I had it down for service due to - cooler days or them not being able to park it in the sun for the period required. I was treated with some odd looks when I would explain that the vehicle had to be parked in the sun for at least an hour or two before the problem would arise. They often suggested that I purchase a new remote just to see if it would work better!? I declined..... One time it did actually play up while at the dealership and they said they fixed it by making an adjustment. Well I went home (380km away) and it was no different! Finally after the warranty had run out, they found the fault was with the Upper Electronic Module which apparently is in the rear view mirror (needed replacement)! The whole mirror had to be replaced and had to be ordered from Sweden - took about 3 months and cost me $521.50 for the mirror, $42.70 for the UEM reload, and $91.35 labour. By this time I was very fed up and just pleased to have it fixed, but I do feel they could have done more during the warranty period. The guys at the dealership said they tried to get VOLVO to cover this as it was a reported fault during the warranty period but they would not cover it. I have had no trouble since this was replaced (Dec 2007). I hope this will help you get your UEM looked at as the faulty part. Sorry for the long post too.
Best of luck,

Bilby, thank you for the response. I just (knew) I could not be the only person having this problem.

Like yourself, I was greeted with some very strange looks from the service manager and others in the service department; all of whom claimed they had never seen or heard of anything like this before (which I cannot believe for one second).

I changed the batteries in both of my key FOB's (one of which has never been used since I purchased the car almost 3 1/2 years ago) which eliminated the FOB's as the cause of the problem.

Now, considering the key FOB uses radio frequencies to communicate with a radio frequency controlled remote locking mechanism in the car, I would suspect the cause of the problem is the receiver mechanism in the car, wherever that might be.

My car is under the original new-car warranty until November, 30th of this year. However, shortly after purchasing the car I had a Astrostart remote starter installed which not only started and stopped the engine, it also allowed you to control the door locks. Fortunately the door lock function was disabled last year as a result of an unrelated problem so I know (that) is not the cause of this problem.

Hopefully, sometime in the next week or two I will be videotaping this phenomenon and uploading it to Youtube.com where other Volvo owners can see it firsthand.