SL/R230: KEY not recognized - no ignition turn
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KEY not recognized - no ignition turn
I am having issues with my 2003 Sl500 R230.
A couple of days ago, my keys stopped working, both the spare and the normal one. I have replaced the key fob batteries, trunk AUX battery, and checked the main front battery voltage v12.7 . I also checked the right, left, and rear fuses, and all came back good.
My keys won't lock, unlock, open the truck or panic; nothing works. When I get into the car and put my key into the ignition.. Nothing ... can't turn the key. It shows KEY NOT RECOGNIZED. I have keyless go as well, tried the door buttons, nothing.. push to start nothing.
When I let the car sit for 20-30 min and push the unlock button, I mean what sounds like the pump in the trunk working. But no light flash, no doors lock/unlock, no truck opens..
I am stuck.. I was thinking maybe it's one of the fuses under the footwell?
A couple of days ago, my keys stopped working, both the spare and the normal one. I have replaced the key fob batteries, trunk AUX battery, and checked the main front battery voltage v12.7 . I also checked the right, left, and rear fuses, and all came back good.
My keys won't lock, unlock, open the truck or panic; nothing works. When I get into the car and put my key into the ignition.. Nothing ... can't turn the key. It shows KEY NOT RECOGNIZED. I have keyless go as well, tried the door buttons, nothing.. push to start nothing.
When I let the car sit for 20-30 min and push the unlock button, I mean what sounds like the pump in the trunk working. But no light flash, no doors lock/unlock, no truck opens..
I am stuck.. I was thinking maybe it's one of the fuses under the footwell?
Senior Member
Joined: May 2020
Posts: 443
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From: North Carolina, USA
2004 SL500AMG, 2003 SL500 USA
Your security component error can be with the EIS. See discussion link below and ECU Pro link.
The H3 Alarm error is probably the corroded NiCad battery in the alarm siren in the driver's side wheel well. It is easy to replace and can cause mysterious problems. However, it does not usually cause no start problems.
SL/R230 Key Fob won’t turn in ignition or unlock doors, new fob battery. Buy fob from dealer? - MBWorld.org Forums above is my post
2004 Mercedes-Benz SL 500 EIS Security System Test | The ECU Pro (the-ecu-pro.com)
The H3 Alarm error is probably the corroded NiCad battery in the alarm siren in the driver's side wheel well. It is easy to replace and can cause mysterious problems. However, it does not usually cause no start problems.
SL/R230 Key Fob won’t turn in ignition or unlock doors, new fob battery. Buy fob from dealer? - MBWorld.org Forums above is my post
2004 Mercedes-Benz SL 500 EIS Security System Test | The ECU Pro (the-ecu-pro.com)
Super Member
Joined: Sep 2021
Posts: 534
Likes: 115
From: Ann Arbor, MI
2004 SL600
For experimentation, I removed the 7.5Amp fuse near the trunk battery; this fuse power the electronics in the EIS.
This gave me almost exactly the same symptoms as in your first post. The key does not turn in the ignition, but I didn't get the "KEY NOT RECOGNIZED" message.
Interestingly when I pressed the unlock button, the light in the trunk (which had been off for a long time) turned on and it sounded like the rear pump turned on too. But nothing would lock or unlock with the key.
I did not connect a scanner.
Your rear SAM error might be the real problem.
Many here remove the fuse for the alarm siren; likely the old NiCad batteries in it no longer hold a charge and will drain the consumer battery attempting to recharge the defective NiCads. I don't recall seeing a scanner error for this begin disconnected.
This gave me almost exactly the same symptoms as in your first post. The key does not turn in the ignition, but I didn't get the "KEY NOT RECOGNIZED" message.
Interestingly when I pressed the unlock button, the light in the trunk (which had been off for a long time) turned on and it sounded like the rear pump turned on too. But nothing would lock or unlock with the key.
I did not connect a scanner.
Your rear SAM error might be the real problem.
Many here remove the fuse for the alarm siren; likely the old NiCad batteries in it no longer hold a charge and will drain the consumer battery attempting to recharge the defective NiCads. I don't recall seeing a scanner error for this begin disconnected.
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Joined: Aug 2020
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From: Gretna, NE
'03 SL55 Black, '03 SL500's Aegean, Mars Red, Tazanite, Alabaster, '11 S550 Flint Gray
Key turn only requires a good EIS with power supplied to it and a matching key. Considering neither key works and you are getting the 'key not recognized' message, my money would be on the EIS.
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Thank you guys for the help! I took out the EIS and got it diagnosed, and it was the EIS. The processor in the EIS was damaged, which causes internal memory to fail, which is unrepairable, so I'm getting a replacement unit and cloning the data over. We'll see how it goes!
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Yeah, the car has only 50K miles on it.
Yes, I went with the ECU Pros out of PA. They have YouTube videos online, seem pretty legit. I am not sure how they will clone the data, but they do have a replacement unit, and they will send me my broken unit back, aswell. So we'll see.
Yes, I went with the ECU Pros out of PA. They have YouTube videos online, seem pretty legit. I am not sure how they will clone the data, but they do have a replacement unit, and they will send me my broken unit back, aswell. So we'll see.
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Super Member
Joined: Sep 2021
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From: Ann Arbor, MI
2004 SL600
Like the ECU I suspect the EIS has an internal EPROM which can be read with a tool like KTAG and the data written into the replacement EPROM. On some automotive modules the EPROM has to be unsoldered, programmed and soldered back in, which obviously takes knowledge and practice.
It is good to know that the EIS can be replaced and re-programmed like this. Otherwise you have to buy a replacement EIS with keys, the transmission shifter, and have the ECU reprogrammed to the new EIS security codes. (Technically you could swap a small module inside the transmission shifter.)
I has assumed the EIS had unchangeable security codes in a ROM, not changeable ones in an EPROM.
It is good to know that the EIS can be replaced and re-programmed like this. Otherwise you have to buy a replacement EIS with keys, the transmission shifter, and have the ECU reprogrammed to the new EIS security codes. (Technically you could swap a small module inside the transmission shifter.)
I has assumed the EIS had unchangeable security codes in a ROM, not changeable ones in an EPROM.
