pranesh

Hi guys. I'm in need of sum great help. My c200 w203 has an intermittant lock and unlock problem but works from the ir receiver. I do hav smash n grab tint on the back glass. Not sure if this causes it. I also ordered a new key and stil no luck. I notice wen this problem arises I pull out fuse no 8 on rear sam and replace after a few minutes. This seems to start workin again but the next mornin we bak to same problem. Plz help.

wtmfi

I'm working on a similar problem on my gf's 02 C240. F8 feeds the RF antenna amplifier AND the alarm system. I've read of problems with shorted amplifiers (in read headliner), shorted alarm siren (behind front passenger wheel liner), and faulty anti-tow sensors (not sure where that is yet).

I'm going to look at it tomorrow. the last time the fuse blew, the front fogs were flashing, so I'm going to start with the siren. I'll let you know what I find.

wtmfi

Sorry... I should have stated that the keyless works on RF, so if F8 is blown, the keyless will only work with the IR reciever on the door handle

SunnyRayToronto

Do NOT use metallic tint

wtmfi

It was the alarm siren on my GF's car.

Pulled passenger front wheel well liner, disconnected siren, and fuse F8 no longer blows. New siren from dealer installed. Put everything back together, and both remotes work properly again. Radio signal back to normal also.

If the remotes stop working "suddenly" (nothing to do with recent tint job), and F8 is blowing, I would definitely check the alarm siren BEFORE pulling the headliner or C Piller cover to check the antenna amplifier

edkelly1966

I have recently purchased a 2002 C220 Coupe as a second vehicle and all has been well except for the last 2 mornings my remote keys will not unlock the vehicle first thing in the morning. I can manually unlock but this sets off the alarm, I can stop the alarm by putting the key in the ignition after which I have no further problems for the day with it locking and unlocking remotely no problem. Am I being stupid and missing something? This is my first Merc and everything else has been fine, I was really enjoying it but I don't want to annoy my neighbors by setting off my alarm every morning as I tend to be up and away when many are still in bed! Any advice guys?

wtmfi

the remotes work in 2 ways. Radio Frequency (RF) for long distance lock/unlock/trunk release, and Infra-Red (IR) up close. There's an IR sensor on both front door handles that you can try by aiming the remote from a few inches away. If the IR works, that should keep the alarm from going off, and it proves the batteries in the remotes are good.

If IR works, then that leaves RF. Common problems on RF could be metalic tint (which will block the RF signal), or a bad RF antenna amplifier (which could have been damaged when tint was installed/trimmed).

Check the IR and get back to me.

edkelly1966

Thanks wtmfi. On both days the problem occurred I also tried the IR at the door handle with no success before having to manually unlock and insert key in the ignition, after doing this the remote central locking worked first time for the rest of that day. However the problem has now only happened for those 2 mornings after which there has been no recurrence with it opening first time every try... Fingers crossed it remains so!