SL/R230: r230 doesent switch off
Thread Starter
Junior Member
Joined: Jun 2025
Posts: 16
Likes: 0
r230 doesent switch off
hi guys, i hope you can help me, my sl500 2005 occasionally wouldnt turn off when the key was turned off and taken out. but it is doing it all the time now. i stop it by removing the ignition relay.
so now it starts off the ignition switch, not much is working , no lights on the dash and it wont turn off.
when i get the engine off, the only way to get the ignition to turn on is by removing the positive lead to the rear battery and replacing it. this seems to reset it and let the ignition turn again.
i had the eis block tested along with the keys, and the guy said there was no problem with it.
also i have pulled out the alarm siren fuse as it keeps going off.
the key fobs are not opening the doors or operating the alarm.
any ideas guys, i need to be using this car, the sun is shining andyfireblade (andy in the UK) thanks
so now it starts off the ignition switch, not much is working , no lights on the dash and it wont turn off.
when i get the engine off, the only way to get the ignition to turn on is by removing the positive lead to the rear battery and replacing it. this seems to reset it and let the ignition turn again.
i had the eis block tested along with the keys, and the guy said there was no problem with it.
also i have pulled out the alarm siren fuse as it keeps going off.
the key fobs are not opening the doors or operating the alarm.
any ideas guys, i need to be using this car, the sun is shining andyfireblade (andy in the UK) thanks
Last edited by andyfireblade; Jun 28, 2025 at 03:23 PM. Reason: spelling
Super Member
Joined: Oct 2012
Posts: 538
Likes: 89
From: Hollywood, CA
W209, W124
Really sounds like a bad EIS to me.
But it could be ECU. Does gear show correctly on dashboard?
I’m gonna guess it’s a cold solder joint somewhere.
Get on a scanner that speaks MB. Something isn’t talking regularly
But it could be ECU. Does gear show correctly on dashboard?
I’m gonna guess it’s a cold solder joint somewhere.
Get on a scanner that speaks MB. Something isn’t talking regularly
Last edited by MacVidMB-V8; Jun 28, 2025 at 09:17 PM.
Super Member
Joined: Sep 2018
Posts: 746
Likes: 185
From: Melbourne, Australia
2005 SL 500 R230
Agree, possibly EIS. There is a known issue with water ingress under the SAMs (fuse boxes) under the bonnet, caused by blocked drain tubes. No idea if corrosion there could be causing your problem but I would pull them both to inspect the various plug connections.
Thread Starter
Junior Member
Joined: Jun 2025
Posts: 16
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thanks for your help, the gears showed correctly on the dash, that is up untill there is nothing on the dash.
thats a good idea about the dry joints. i might go round all of the connections with a wiggle and a spray of oil.
thats a good idea about the dry joints. i might go round all of the connections with a wiggle and a spray of oil.
Thread Starter
Junior Member
Joined: Jun 2025
Posts: 16
Likes: 0
thanks for your help, i had the EIS checked with the keys, and the guy said there was no problem.
good point about the fuse box under the bonnet, that's where the ignition and starter relays are, of coarse you know.
i will have a look at that although there is not much access and it looks like the bonnet hinge is in the way for removal of the box.
thanks andy
good point about the fuse box under the bonnet, that's where the ignition and starter relays are, of coarse you know.
i will have a look at that although there is not much access and it looks like the bonnet hinge is in the way for removal of the box.
thanks andy
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Super Member
Joined: Sep 2021
Posts: 541
Likes: 117
From: Ann Arbor, MI
2004 SL600
Next time it stays on, try removing the 7.5 Amp fuse on top of the small fuse block in front of the rear battery. This powers the electronics of the EIS, and if removing its fuse shuts down the car, we have an important clue.
Super Member
Joined: Sep 2021
Posts: 541
Likes: 117
From: Ann Arbor, MI
2004 SL600
I'm confused. Earlier you said "it still runs even when the eis unit is totally unplugged". Do you mean that both the big and small connectors behind the EIS were disconnected? I don't know how that could be.
Now you are saying that removing the 7.5 Amp fuse by the rear battery kills the engine; that is expected as that powers the electronics in the EIS, presumably through the small connector on it.
Now you are saying that removing the 7.5 Amp fuse by the rear battery kills the engine; that is expected as that powers the electronics in the EIS, presumably through the small connector on it.
Junior Member
Joined: Nov 2023
Posts: 28
Likes: 3
06 SL500
There's something of an issue with ignition switches and old MB's. I've read about them and what to do. My key used to 'stick" in the ignition and not want to come out once in the while. Can be the start of a real problem, expensive I think. Fortunately a shot of graphite seems to have fixed it (18 months later, knock on wood).
