R230 SL...advanced Central Locking Infrared query

Vlad

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Ok so I have a 2003 SL350 which has a problem that is not uncommon, ie central locking only works if you place the key right next to the infrared sensor on the drivers door. If you step back 1 metre it wont work.

So far the following has been done.

1) New infrared sensor replaced in drivers door handle....no difference

2) Vehicle has been placed on STAR and nothing particularly meaningful if coming up.

3) New amplifier/antenna has been installed on right hand A pillar....no difference

My Indi is now saying that its likely to be the windscreen itself and they've done a couple. Big gamble as a new windscreen is £590 + fitting. Apparently the amplifiers work through the inbuilt antenna in the windscreen which then amplifies the infrared signal from the key to the central locking, which sounds plausible. Apparently the connections into the windscreen can break

However, before I embark on that route I have also read that the N70 dome module in the roof, ie where the internal roof lights sit, can also play up, as the signal from the amplifier in the right hand pillar goes to this module, again for the central locking.

Has anybody got any further clues or inputs on this, as this is driving me up the wall and I just want it sorted.

I should also add that both keys are working and have had new batteries
 

whitenemesis

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IR is only line of sight and very short distance operation using the door handle. The antenna and amplifier will be for the RF operation.
Surprised STAR didn't show any error codes.
If the key fobs have been dropped the little signal coil may have come adrift?
 

flowrider

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If its the IR having issues why did the garage replace the antenna amp? The windscreen and antenna amp have nothing to do with the IR, they are RF only. Have you had the keys tested? I have been through a similar issue recently on my SL but in my case neither RF or IR worked. Despite the keys tested by the indi and testing ok, it was the keys at fault. My indi said he had tested them on his basic key tester but a more thorough test by an auto electrician showed they were faulty.

My SL had no error codes either.

BTW, I would be asking the garage to refund all the cost of the antenna amp if they haven't done so already, that's a basic mistake they made.
 
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Vlad

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I may have got some of my terminology wrong...I assumed it was IR that was at fault as I had it in my mind that it was IR that operated the central locking and was boosted by the amplifier.

The amplifier by the way has gone back to MB and I've not been charged.

Anybody ever heard of the windscreen giving issues?
 

flowrider

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I may have got some of my terminology wrong...I assumed it was IR that was at fault as I had it in my mind that it was IR that operated the central locking and was boosted by the amplifier.

The amplifier by the way has gone back to MB and I've not been charged.

Anybody ever heard of the windscreen giving issues?
Whilst not out of the question i have not heard of the windscreen being an issue. I would look further into the keys, both my keys had an IR signal, both keys had an RF signal but both were weak due to dry joints within the keys circuitry.
 

SMS

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The infra red works but not as efficient as it should be, but works however the radio transmitter doesn’t, key output is good. No faults shown on star test. We replaced a screen last year with the exact same problem, yes it’s a bit of a gamble and this was explained as there isn’t a fault showing and all values are correct. Cheaper if the windscreen was covered under insurance?
 

ToeKnee

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Does the ir actually unlock the car? I thought it was purely for the global open/closing feature? If I'm correct then the rf must be working a bit to unlock the car once close, so maybe it is the key that's at fault for not giving out a strong signal.
 

flowrider

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Have you looked into the EIS. If IR and RF is a problem, and you are 110% confident its not the keys, then this is the next component common to both RF and IR. However my money is still on the keys being at fault. :)

Have you tried a new key?
 

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