SL500 remote not working

[laf]

Hi Everyone,

I have a 1996 SL500 R129.

My remote locking/alarm arm, disarm has suddenly stopped working.

I unlocked my car this morning, and started it up as usual. I then turned it off and went to to lock it but it wouldn't lock. The immobiliser has armed now and I can't start the car.

I've tried two remotes.
I've checked the remotes are working by looking at them through my phone camera (I can see the light come on when I press the button).
I've tried the lock reset procedure in the manual (point remote at mirror, press button twice then turn ignition to position 2).

Nothing works.

What I do notice is that when I turn the key to position 2, the red light in the mirror flashes (about once per second).

When I try to start the engine, the red and green light DON'T flash. I would normally expect them to flash.

Has my immobiliser/alarm given up the ghost?

Can anyone help? I'm going to go and buy some new batteries but I don't think that's the problem.

Thanks,
Lee

 

[laf]

A quick update: I replaced the batteries in remote #1. That didn't work so I swapped the batteries from remote #2. I did this as quickly as possible.

Still no joy. When I press the remote button, though, I notice that some times, the red light on the mirror flashes. Not pressing the button the light stays off.

I hope this helps.

Thanks,
Lee

 

[television]

Do try putting the key into the ignition and quickly press any button on the remote

 

[laf]

Hi Television,

Tried that but no joy.

It's weird how the lights on the mirror don't flash when I try to start the car. Normally they would if the immobiliser is on.

 

[television]

I know that it is annoying to disconnect the battery on a SL but this could enable the alarm to re set, you would have to re sync the windows and possibly the roll bar

 

[laf]

Hi Malcolm,

Thanks again. I tried that (disconnected the negative). I left it disconnected for 10 seconds and reconnected it. Still no joy :cry:

When I press the remote button, the red light on the mirror just blinks once.

It looks like I'm going to have to get it to Mercedes. I can hear my bank balance groan at the thought of it. And! it looks like it will be next year now too. The up-side is I'll lose the weight I put on over Christmas.

Thanks again for your help. Any more ideas for me to try will be gladly appreciated?

 

[television]

I will see if there is anything else in WIS on this

 

[laf]

Hi,

Just a quick update on what I've tried today.

I have a smaller second key with each remote key; I assume this is to disable the alarm/immobiliser. I found a few references on forums suggesting a few places where such a disable switch could be. I also re-read the handbook but can't find any reference to it. Searching the car (in the cabin, under the bonnet and in the boot), I couldn't see anything either. So I gave up.

Next I disconnected the battery for 10 minutes (with the doors locked). I then unlocked the driver's door with the key and the window wound down halfway. I tried to start the car but still nothing - no flashing lights under the mirror either.

I wound the driver and passenger windows all the way down and then all the way up and they're working fine again. So everything works except the car won't start.

The only thing I can think of what changed between the car running and then the remote not working is that when I opened the door to take the key out, it swung right open. I wonder if that could have disconnected of wrenched something in the door? It's almost as if there's an error condition rather than something not working because pressing the remote makes the red light blink once.

If I do end up taking this to a dealer, do you think they'll be able to find the fault using the diag computer or will it be an expensive bug hunt?

Thanks for your continued help,
Lee

 

[laf]

Fixed it!

It was fuse number 15!! Replaced the fuse and it fired straight up.

It does beg the question of why can't you start the car just because the IR remote fuse blows? Why no manual override?

Anyway, thanks for your help,
Lee