Remote won't always work

[Wafter]

I have a problem with the Mercedes approved alarm/imobiliser on my 1994 E280. On average, about once a week, the remote refuses to either lock or unlock the car. The red light on the zapper lights up but nothing happens. This is very embarrassing when it won't work and using the key to get in just sets off the alarm when you then open the door. The alarm is also set to passive mode so that it self activates after 20 secs on the last door closing. This means that you can't just use the key to lock and unlock the doors and not use the alarm. I tried to disconnect the alarm by using the special round key in the unit under the bonnet but all that does is to turn the siren on or off.
If I play with the remote long enough (longest time 25 minutes) it eventually works and unlocks the car.
This can happen anywhere, usually in supermarket carparks when you end up looking like a car thief, and I have put new batteries in the remote. Any ideas anyone?

 

[Orlando 300E]

This may be a silly question, but have you tried a new battery in your alarm fob.
Mine starts playing up, similar symptoms, when it starts running low.
good luck
Orlando

 

[Wafter]

Yes Orlando, I put new batteries in the first time it happened. I've just been out and it happened again. Took 3 minutes of walking around the car pressing on the fob before it finally unlocked. Can't think of anything else to try, but thanks for the reply.

 

[grasmere]

Since replacing the battery was flat have you tried 'resetting' the key fob via the sensor?

When I got my car 2 of the spare fobs did not work even with new batteries in them. I was going to dispose of them when I read the manual which described how to reset them - something like holding down the button or pressing twice did the trick and all was fine. Check your book and if theres no mention I'll tell you what mine says for a C220 1996

 

[maddog]

Mine started doing that on my 01 E320 cdi , i replaced the battery but it soon started playing up again so i mentioned it to MB at the last service .

They ordered me a new one under warranty and have just replaced it for me.

 

[TonyCoolDaddy]

I had the same problem with volvo 1997 V70, resetting the remotes cured it although one remote "lost" frequency after 2 weeks

 

[Wafter]

Thanks for all the information guys.

Grasmere:- I only have a 4 page pamphlet that says nothing about 'resetting' the key fob. What's the drill for your C220 please?

Maddog:- Did you mean that they replaced the battery or the fob itself? Will MB care about a 10 year old Scorpion alarm?

TonyCoolDaddy:- Again, how do you reset the remote?

Thanks for all the help.

 

[maddog]

Sorry i thought you were referring to the MB alarm/imobiliser in my case they replaced the whole key fob.

For your alarm you need to bear in mind a new installation costs around £200 and replacement key fobs often cost £60 each!!!

 

[grasmere]

Hi

For the MBSS installed in my C220 D 1996, I think its a Scorpion, but no way to tell as far as I can see. In my 4 page MBSS booklet ther is no mention of resetting a problem system. The process is however referred to in the manual as 'synchronising the lock system' if the car cannot be locked or unlocked, page 40 in mine.
Quote: . . .
1. Aim the transmitter of the remote control at the receiver in the interior mirror and press transmitter button briefly twice.
2. Turn the key in the steering lock to position 2 within about 30 seconds.
3. The lock system is then operational again.
. . . Unquote.

Good luck

Ian

 

[Wafter]

Cheers Ian, I'll give it a whirl tomorrow - assuming it opens that is!
Thanks for your trouble.