There is no electric lock for the fuel cap. The only electric lock is the one on the trunk latch controlled by the PTCM. WHERE is the sound coming from?
Here is how it all works:
Fob talks to SKREEM which tells the Body Control Module which tells the CLP/SSM to lock or unlock.
or...
Button on console tells the Body Control MOdule which tells the CLP/SSM to lock or unlock.

The turn signals are flashed by the SKREEM when you use the FOB.

If there is a CAN BUS failure between the BCM and CLP/SSM, I can see it manifesting in the way your car acts. But almost EVERY time, it's the damn CLP/SSM.

 

Okay... this CLP/SSM is the black box with the vacuum pump and PC board in it... right? If so, I've replaced that with the other one I bought some time ago for the harness, and nothing works... no vacuum pump for the lock system... nothing. So I unsoldered the pump and tested with 12VDC and it works fine. I took my original pump off and tested it... IT works fine too. So, something that is supposed to energize that pump ISN'T. Now this leads me to believe that the vacuum RELEASES the locks and a spring/solenoid LOCKS things because it locks when the car is NOT running, nor is that little pump, and since I always used to start the car and hear that little pump running when I hit the key--even without engaging the start position--but just in the 'on' position of the key switch. Is there a vacuum chamber that holds vacuum as a reservoir? The wiring looks fine with NO signs of corrosion or green anywhere. Sigh. If replacing that CLP/SSM isn't the issue (and I realize it may still be, and that the 2nd one may also bad even though there is NO sign of any moisture issues with this one), then what? Go and buy a THIRD CLP/SSM only to find it is something else? I've reassembled both CLP/SSM units and will put the original back in and hook up the wires and vacuum... then I'll try testing with the car running and NOT running and see what I get. Love this car, but absolutely HATE Mercedes electrical engineering... way too far over the top of what's necessary.

 

Okay... this CLP/SSM is the black box with the vacuum pump and PC board in it... right? Yes.

If so, I've replaced that with the other one I bought some time ago for the harness, and nothing works... no vacuum pump for the lock system... nothing. OK

So I unsoldered the pump and tested with 12VDC and it works fine. I took my original pump off and tested it... IT works fine too. So, something that is supposed to energize that pump ISN'T.
The pump is operated by the controller board in the CLP/SSM Thats why they call it that, it's the Central Locking Pump/Security System MOdule. The pump/motor combo NEVER goes bad, it's always the controller.

Now this leads me to believe that the vacuum RELEASES the locks and a spring/solenoid LOCKS things because it locks when the car is NOT running, nor is that little pump, and since
No. THe pump sends PRESSURE to the locks to unlock and sends VACUUM to the locks to lock. See the really good details in the service manual.

I always used to start the car and hear that little pump running when I hit the key--even without engaging the start position--but just in the 'on' position of the key switch. Is there a vacuum chamber that holds vacuum as a reservoir?
No, see my post above. And the pump DOES NOT run when you start the car, it will lock the doors at about 8mph, tho, that is automatic, but the pump does not run just because you start the car.

The wiring looks fine with NO signs of corrosion or green anywhere. Sigh. If replacing that CLP/SSM isn't the issue (and I realize it may still be, and that the 2nd one may also bad even though there is NO sign of any moisture issues with this one), then what? Go and buy a THIRD CLP/SSM only to find it is something else? I've reassembled both CLP/SSM units and will put the original back in and hook up the wires and vacuum... then I'll try testing with the car running and NOT running and see what I get. Love this car, but absolutely HATE Mercedes electrical engineering... way too far over the top of what's necessary.

The CLP/SSM system is on battery power, it's operation has little to do with the key being on or off. PLease read thru the "Vehicle Theft Security" chapter of the service manual and you will be way more up to speed.
I still question the CLP/SSMs but I admit this may be a CAN BUS or BCM (Body Control Module) issue. But the thing is, you MUST understand how it works and some of your statements above are WAY off base and I urge you to read thru that chapter of the service manual and SO MUCH will be clear to you. You are troubleshooting by GUESSING and that is going to lead you astray badly.

THis leads me to make a basic statement: The symptom-function troubleshooting method is based upon a good understanding of the system you are troubleshooting. The really good techs/engineers/fixers are those who understand the system the best; this understanding has to be more than a theoretical understanding, which is why a lowly tech can often find and fix a problem faster than the engineer who designed the system. This is why my "engineering" title is not really why I am valuable to the company, it's because I have done my job for 40 years.

ONE MORE TIME: Download the service manual. The manuals are ALL here:
CLICK THIS!

 

Alright... battery power yes, but it ALWAYS came on (that little pump) when I turned the KEY on, and before it would crank over. So the key must have something to do with energizing that little pump... This problem only started when that little pump stopped working so it seems. I did just 'park' and go away, come back a day later and the problem was there. I've downloaded a bunch of manuals and will begin reading on the "Vehicle Theft and Security" section right away. Thank you. Here's where I 'seem' to be right now... I installed the "replacement" module and the flashing red light stops, and I can start and drive the car. NO locks are working via the FOB, but I can manually lock the doors from inside, and using the lock button on the dash, my doors are locking and unlocking electrically, but NO vacuum. The fuel door has remained unlocked which is fine with me... at least I can drive and fuel the car while I am reading and trying to figure out this mess. Thank you, again, for all your help. BoB

 

I think you are hearing the fuel pump prime when turning the key to “on”.

 

If the doors are locking and unlocking, you have pressure and vacuum. Again,please read thru that chapter of the service manual and you will understand more.

 

Exactly.

 

Yes... you are probably quite right on that as is sounds like it's coming from the rear area... but I'm not hearing it anymore and the car is running fine???

 

Hi Bob,
I wouldn't take the fuel pump being quiet as a sign of anything being wrong. If the line stays pressurized, the pump won't come on, or sometimes it doesn't vibrate as much. I put a pressure gauge on the fuel rail to check the fuel pump pressure. I bled the line, and then jumped the fuel pump relay at the RCM - never heard the pump go on, but the pressure in the rail shot up to 60 psi and stayed there.
-Jerry

 

Hi... I downloaded that manual, and I've 'tried' to read and understand that section 8Q on security, but I might as well be reading in Chinese. I'm okay on normal 12VDC wiring and such, but THIS is way out of my scope of skills. I don't even understand what they're telling me to do as a test, let alone "understand" this system. So, if you guys can't help me figure out why upon replacing the large module in the trunk well did NOT restore my vacuum locking system, or interior lighting (but DID restore my headlamp delay function) then I will have to take this vehicle to a dealer (God help me!). I'm not stupid, but also NOT an EE. I've tested the vacuum pumps on BOTH of the modules I have by removing them from their boards and apply in 12VDC and both pumps run fine. This tells me that some "brain" somewhere in this ridiculous system is NOT sending current to the vacuum pump when it should... that's about as far as I have been able to get so far and reading this manual did not help at all. Still needing help in Massachusetts... BoB

 

Iv got to re-read the thread to see where you are, been helping so many people on FakeBOok I can't keep track of who is doing what. Taking the car to a dealer won't get it fixed, they have no factory support for the Crossfire anymore, you are better off to keep chugging along alone.

So just to summarize:
Car starts and runs, door locks work using the console button, but not the key fob, but when you hit LOCK or UNLOCK on the fob, the turn signals flash. Is that a good summary of where we are at now?

GOtta work, back tonight.

 

Any ideas yet? It's all apart in the back for weeks now. Thanks in advance!!

 

YOu didn't answer my question.

 

Yes ... your summary is VERY correct. I did answer, but I can't see the answer either. God only knows where THAT ended up. Sorry!

 

This one is hard.

We know the SKREEM is decoding the FOB signal, because the SKREEM is flashing the turn signals.
We know that the CAN BUS from the BCM to the CLP//SSM is OK, because the console switch works.
We know that the CLP/SSM's pump is OK, because, again, the console switch works.

The driver's door lock cylinder is wired to the SKREEM, so if you unlock the drivers' door with the key, the SKREEM should tell the BCM, which then tells the CLP/SSM that an authorized unlock has happened and the alarm can be disabled. If you are not getting an alarm after unlocking the driver's door and opening the door, then we would expect the FOB to also work.

If you look in the service manual at the "Power Door Locks" section in the wiring chapter, you will see the control lines from the SKREEM to the BCM:

C4 - 57: Door Lock Switch Sense
C4 - 55: Door Unlock Switch Sense
C4 - 59: RKE (Remote keyless entry) Status

These pins are how the SKREEM tells the BCM when the FOB buttons or door lock cylinder are manipulated. I"ve never looked at these lines act in response to the FOB or key in the door. I may do a test or two this afternoon - that point is where you determine if the SKREEM is telling the BCM what to do, or not.

 

I am getting NO alarms... I manually lock the passenger's door and it STAYS locked until I use the panel rocker switch. I manually lock and unlock the driver's door with my key. The trunk lid does NOT lock, nor is the fuel door locking (which right now is okay so I can drive the vehicle). As I stated, one "missing" feature (the headlamp delay) DID return when I installed the 2nd BCM.

 

Well, "ONE DRIVE" SUCKS.

I am unsure what happened, but I started up my "lab" computer (I have three PCs here) and it said, "One Drive has removed files". I noted that a lot of stuff was gone.
Booted one of the other PCs, same files were gone. Checked One Drive recycle bin - nothing there. File history in Windows is also gone.

So, I lost TONS of stuff, including most of my Crossfire documentation. I have logged out of ONE DRIVE, never to allow it to screw me again. I am restoring from my fourth PC (the one I have not used since I bought my new one early this year) and will then get into my stuff here and on Fakebook to grab the rest of what I have. Not sure what all this has cost me at this time.

Tomorrow (or today) I will go get a huge external drive for backup. No more online backups.

So gimme a few days to get my s*$% together.

 

"did NOT restore my vacuum locking system, or interior lighting" from your post 30

Have you check fuse #9 under the hood fuse box?
If you haven't disconnected the siren under the windshield cowl, you should

 

Hi... any luck in recovering your stuff? I feel horrible about that and hope that I was in no way connected to this loss.

 

So basically for me. The SKREEM is going out because no signals flash anymore when pressing the fob. I have a used fob and tried to program it but no luck. So signals or anything.