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Hey everyone, working on my 2007 SL, It is giving me some electrical issues. Was getting multiple electrical codes, and I cleared everything.
Getting these codes
N10/N11 Passenger SAM control unit is defective. If no customer complaint fault can be erased, Tried clearing but still coming back
Terminal 15: Short Circuit to Positive
Terminal 15: Short Circuit to Ground or open circuit
The car seems to have some sort of battery draw. It startes perfect sometimes and then is totally dead.
I have replaced both batteries and checked the alternator, which is fine. I checked all fuses.
I think the Passenger SAM is bad or something in the pre-fuse panel. I will check these next.
If your only symptom is battery drain, I would start by trying to pinpoint the drain. Common issues are the alarm siren and the Teleaid module. The rear battery positive has branches to the rear prefuse and the BCM. In turn, the BCM branch has an alternator connection and a connection to the front prefuse. You will have to wait several minutes until the car is in full sleep before measuring anything.
I have seen the SAM defective warning. Not sure what it looks at, but I have cars that are fully functional with very low drain that still throw that code.
I'm still learning the R230 electrical system, so take my thoughts with many grains of salt, but let me go out on a branch which will help me learn more too.
Circuit 15 is hot when the ignition switch is on. Circuit 30 is always hot. Not sure what circuit 87 is; something after a relay.
Having recently removed my EIS (for making more keys), I see that it has high amperage connections. Correct me, but I think one goes to the 80 Amp fuse in pre-fuse F32 which is in the passenger footwell. (For which unspeakable things should be done to whoever decided on this location.)
Not directly related, but the 7.5A fuse by the rear battery (pre-fuse block F52) provides signal power to the EIS, meaning the key will turn even if the 80 Amp pre-fuse in F32 is blown.
I don't know much about the front right SAM, but this SAM is more expensive ($200+) on ebay than any other SAM, which indicates there is a higher demand for it. (I have bought spares of all SAMs and most modules.)
Good luck with you diagnosis. I'm eager to learn how you solve it. Hopefully its not an intermittent 80Amp fuse in F32.
You simply have to measure the current drain first to know where you are. You're looking for 50 - 70 mA at rest but know that you have to wait as mentioned and that the car has to be locked.
The car seems to have some sort of battery draw. It starts perfect sometimes and then is totally dead....
What is dead? No crank, or no power etc? Car will run with a dead rear battery, but will just crank slowly with a low front battery.
Completely dead may mean a dying or dead EIS or bad connection in one of the pre-fuse blocks as mentioned.
so I charged the battery overnight. The car started right up and now I am getting this on the dash. I have an Autel, Icarsoft and foxwell. I am not sure if I can access the SAM to check the volts so might have to do manually.
Thanks Tom, yes have repeately cleared them and they keep coming back. Sometimes rear sam, sometimes side. For the hell of it I am going to replace the alternator tomorrow. If that does not do it the only thing can be the module or one of the pref-fuses. All of the voltages are good.
If the rear battery shows a voltage above 14.2 volts when the engine is running, you can assume the Alternator is good.
The "Alarm Signal Horn" can be ignored as Tom said because it likely was disconnected by a previous owner because they are notorious for battery drain.
I'll guess an intermittent regulator in the alternator, but you have to put a voltage logger on it to know. There was an issue with it from new but I thought it was solved by 2007. Sound idea just to replace it.
Alarm - if the brown 7.5A fuse in the LHS fuse box is blown or missing it's probably the internal battery in the siren. They leak, short out the board and blow the fuse.
I just remembered that on later cars the regulation was done by the engine ECU and not the alternator. Check if yours has a removable regulator, if so you can just replace that. Not sure what year the change was.
This is driving me crazy, I am checking thre pre fuse in the passenger footwell right now. Will update later. I also ordered a new alternator just to rule it out.
Please educate me - Does the OP's red "Battery/Alternator Stop Car" message correspond to the B1013 or other code? Seems you should get a more obvious low voltage code. I also wonder if anything other than the BCM monitors battery voltages.
Since I now have my BCM fused, I plan to soon remove the fuses and start the car to see what codes I get.
If you cut the connection or remove the fuses you'll get a bunch of portentous messages about the brakes as the system thinks it's lost power to the SBC, as it can't pull in relay K57, allowing the system to run from the front battery.
Have your tried using your diagnostic to clear the red battery fault on dash? I had this from an alternator issue, however when I changed the alternator it did not immediately get rid of the red battery warning, I had to use the diagnostic to remove it. Have you unplugged your siren? if the batteries inside are worn out, you will get the fault on the diagnostic.
Yikes, that does sound expensive.
If you had posted earlier it needed a new ECU, I would have suggested buying a replacement on ebay and having a cloning or tuning service transfer the VIN and security codes from your old one to the new one.
Still, glad you have it all working now. I see you joined this forum in 2003, so you must have had at least one MB well before your 2007 SL.
"Alarm - if the brown 7.5A fuse in the LHS fuse box is blown or missing it's probably the internal battery in the siren. They leak, short out the board and blow the fuse."
Invaluable insight - that'll explain why my fuse had blown and blew the replacement in short order. Do you know where the siren is located please?
The alarm is in the back of front left wheel-well.
It contains a circuit board, two non-replaceable rechargeable batteries and a horn.
I read that a common problem is that the two batteries no longer hold a charge and thereby put a significant constant drain on the car battery. Hence many just pull the fuse.
if its blowing a fuse, then either the two batteries are shorted or there is a short in the circuit board.
The batteries usually leak acid onto the board and at that point it’s shorted out. I believe the battery drain is from the alarm activating the lights repeatedly when it goes south. It was for me, and got worse when I either washed the car or drove in the rain. None of the 7 cars I have with these sirens are connected.
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