RF lock/unlock works in cold weather only ?

Bonifatich

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Jan 20, 2012
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C200K W203 2001reg
Hello all,

Problem
RF lock/unlock misbehaving

I am reduced to locking/unlocking my car via IR only, for a while now.

However, recently as the cold weather has arrived the RF suddenly has started to work again but only if the temperature outside or inside the car remains at or roughly below 5C.

So I am really confused what the problem is and how do I begin solving it?

Things like fuse 8 is fine, radio also works alright, no tinting

Thanks
 

wongl

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When an electronic circuit is sensitive to temperature I would suspect a 'dry' solder joint somewhere. Hairline cracks can be affected by the temperature; as the temperature drops the metal contracts...
 
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Bonifatich

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C200K W203 2001reg
I see! So is this something that can be repaired or might as well get a new antenna amplifier and replace it?

Thanks
 

Dec

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Is the car alarm in full working order?

Dec
 

wongl

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A180CDI, B200d, C300h, SLK250
I see! So is this something that can be repaired or might as well get a new antenna amplifier and replace it?

Thanks

If you can remove the module from the car, I would get it to a 'decent' electronics technician and ask them to have a look at it for dry joints. See if you can get them to 'reflow' the solder joints.

Technicians with the correct tools and/or skills to do this will usually be mobile phone or laptop repairer technicians. But do choose a competent one to prevent them doing more damage to your module (or even 'frying' it in the process!).
 
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Bonifatich

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Car
C200K W203 2001reg
**Dec**

The alarm is in good working order.

I know it, because I recently had to replace EIS because it suffered with the same problem I now have with RF which **wongl** suggested, which actually seems probable.

Since the EIS would freeze overnight, the car would not open via RF or IR but via metal key only and siren would wake up the whole neighbourhood while i was there with the hair drier heating the damn thing.

**wongl**

If you have or know a post that has guidance on how to take roof cover down including amplifier that'd be great, otherwise off I go to look for one and look for decent electricians in Hants...

Thanks
 

Dec

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When you lock the car with the remote fob, the alarm is armed, opening the door with the metal key blade will trigger the alarm, the metal key blade is for emergency entry into the car, it will not disarm the alarm, only the remote fob can do that.

If that were my car, I would unplug the alarm siren, I know the alarm appears to be in working order but a 13 year old alarm siren just can not be trusted. Unplugging the siren is an inexpensive test which may or may not cure the RF locking problem but worth a try.

See… Alarm / Siren Issues : Goes off for no reason/Kills Battery FIX DIY.. - MBWorld.org Forums

Dec
 
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Bonifatich

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Dec

From the link you added, I could not find where siren causes broken RF signal, but I agree, taking siren down is an easy job to try...
 

Dec

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The link above was intended to illustrate the condition these alarm sirens get into when the age, if your siren were to be faulty like the one in the link then its best unplugged if its not working properly.

There may or may not be a link between your alarm and your RF fault.

Dec
 

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