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SL 55, Stalled while driving won't crank, OBD2 can't communicate with comouters
Hello,
I would really appreciate any thoughts on diagnosing the following problem for a 2004 SL 55 AMG.
I was driving the vehicle when it suddenly stalled. There was no warning lights on the display but the engine cut out. I put it in park and try to restart and got nothing. The shifter is now stuck in park. I tried two separate diagnostic tools including Carly for Mercedes but I am unable to communicate with any of the computer modules even though there is power in the port. I can insert and turn the key on the ignition. The key fob operates the alarm/doors.
Some items such as the horn does not work even though it was functional beforehand however lock in unlocking turn signals lights wipers everything selse seems to be operational.
I have checked fuses and relays and also cleaned front left and front right same contact points. There was some corrosion there and also in the boot. Cleaning did not seem to have made a difference.
I currently get an ESP display malfunction and the red battery icon. Note that the consumer battery was a bit weak but I had been driven it for several months without any issues. The starter battery is strong and fully functional.
One curious aspect is that the car has the exact same symptoms even when I completely remove the connections to the engine ECU.
My running assumption at the moment is that it is either the electronic ignition switch (EIS), engine ECU, or the Central gateway module? Does anyone know where the Central gateway is? I have looked under the passenger footwell after removing metal cover and Bose subwoofer. I can see the black transmission control module (,I think) but not the central gateway.
Any other suggestions? Keep in mind that there is no crank I do not hear the fuel pump running and I am unable to communicate with any of the computers. Thank you so much.
If it was my car I'd:
1) Disconnect the consumer battery
2) Disconnect the starter battery, after the consumer is already disconnected
3) Charge both batteries up while completely unconnected to the car
4) Check the trunk and passenger floor to make sure they are dry. Common areas for water
5) Connect the starter battery
6) Connect the consumer battery, after the starter battery is connected
7) Try the diagnostics to see if you can access anything
8) Turn the ignition on, but not start
9) Try diagnostics again
10) Cross my fingers and attempt to start the car
If it was my car I'd:
1) Disconnect the consumer battery
2) Disconnect the starter battery, after the consumer is already disconnected
3) Charge both batteries up while completely unconnected to the car
4) Check the trunk and passenger floor to make sure they are dry. Common areas for water
5) Connect the starter battery
6) Connect the consumer battery, after the starter battery is connected
7) Try the diagnostics to see if you can access anything
8) Turn the ignition on, but not start
9) Try diagnostics again
10) Cross my fingers and attempt to start the car
I tried this but without any change. I did however find that one of the connectors for CAN B on the passenger side was corroded and when I tried to pull out to clean it broke. Could this be the issue? See photo below. Also, there was a pink connector that wasn't plugged in at all.
I think you might have to remove the cover under the dash to get to the central gateway or the system diagnosis module. Up thru 8/03 is system diagnosis, 9/03 and later is central gateway. Assuming that you have central gateway, it connects directly to the diagnostic port, so if it is functional and has power, you should be able to read faults with an OBDII based tool. DAS reads off of several sources, so you might have better luck finding fault codes with it. For example, ECU is read on K-Line, and other systems are read on extra pins not used in OBDII.
I think you might have to remove the cover under the dash to get to the central gateway or the system diagnosis module. Up thru 8/03 is system diagnosis, 9/03 and later is central gateway. Assuming that you have central gateway, it connects directly to the diagnostic port, so if it is functional and has power, you should be able to read faults with an OBDII based tool. DAS reads off of several sources, so you might have better luck finding fault codes with it. For example, ECU is read on K-Line, and other systems are read on extra pins not used in OBDII.
I appreciate the help. I was able to find the central gateway on the passenger side. No visible signs of corrosion or other damage. I cleaned it. Interestingly enough, only one of the two connectors was plugged in on the gateway. No other connector was around. See photo below.
Would the icarsoft diagnostic tool use a similar protocol to the DAS? Also, note that the engine ECU is getting 14.6 volts as tested through a voltmeter on one of the connectors.
Is there power at and a good ground at the gateway connector? Should be battery voltage at pin 6 (ground is pin 1). Fuse is fuse 8 on the drivers side fuse box. Pin 4 on the gateway connector is wired to pin 14 on the OBD connector, pin 5 goes to pin 6 on OBD.
The small connector on the gateway is for the (obsolete) emergency call system, so no worries there.
Is there power at and a good ground at the gateway connector? Should be battery voltage at pin 6 (ground is pin 1). Fuse is fuse 8 on the drivers side fuse box. Pin 4 on the gateway connector is wired to pin 14 on the OBD connector, pin 5 goes to pin 6 on OBD.
The small connector on the gateway is for the (obsolete) emergency call system, so no worries there.
I will use the voltmeter tomorrow to check just this. I have checked all fuses and they seemed fine I take it you are not concerned that I found that one of the CAN B connectors was damaged as shown in the image below.
Is there power at and a good ground at the gateway connector? Should be battery voltage at pin 6 (ground is pin 1). Fuse is fuse 8 on the drivers side fuse box. Pin 4 on the gateway connector is wired to pin 14 on the OBD connector, pin 5 goes to pin 6 on OBD.
The small connector on the gateway is for the (obsolete) emergency call system, so no worries there.
I confirmed battery voltage at pins 1 and 6 of the central gateway. Note that I also checked that there is 0 voltage at the purple wire for the starter on the front left/passenger SAM/ fuse area when attempting to start the engine. Doesn't that point most likely to an EIS issue?
I am not saying that you don't have an issue with CAN-B, clearly there are some things that need work. However, I don't see CAN-B being the source of your issues. I don't believe that a CAN-B fault would cause a stall/no start problem.
In any case, my priority would be to get communication with the various modules and see what codes are stored and current. If you can't get an ODBII reader to work (maybe a bad central gateway), I would try to get someone with DAS to scan it.
I took out the EIS (easier to do through the command unit opening). Opened it up and don't see any obvious signs of corrosion soldering problem. Perhaps it is the front passenger SAM.
I confirmed battery voltage at pins 1 and 6 of the central gateway. Note that I also checked that there is 0 voltage at the purple wire for the starter on the front left/passenger SAM/ fuse area when attempting to start the engine. Doesn't that point most likely to an EIS issue?
Thank you so much.
No, the start relay is energized by the engine control after getting authorization from the EIS and ESL. No power out of the starter relay just means that it isn't being turned on by the ME-SFI (engine control) module.
,
With dealer level diagnostics you can see if the EIS has authorized a start. If it hasn't, then the EIS, ESL, and CAN-C wiring would be suspect and the problem could be narrowed down further with codes from those modules. If it has authorized a start and the ME-SFI doesn't attempt to turn on the start relay, it is most likely a fault in the ME-SFI (or connection between the ME-SFI and the start relay coil). The general idea is that the EIS first reads the key. If the key is a match for the vehicle, it checks the ESL to make sure it is properly coded to the vehicle. If that is okay, it communications with the ME-SFI and gives it start authorization (this is encrypted and is a 'secret handshake' to make sure that both modules are properly coded to the vehicle).
In other words, you need a working and properly coded key, EIS, ESL, and ME-SFI all able to communicate in order for the starter relay to be engaged.
Remarkably, a $120 Foxwell NT510 Elite can do this. The Foxwell is reviewed and discussed in this sticky.
Drive authorization is checked with the key in position 0. If it fails, the key can not be turned to position 1 or 2. In position 2 the key is checked periodically, and if at any time it fails, then the vehicle behaves generally as if the key were back in position 0. Consequently, the operation of the power windows is a litmus test for the key passing authorization in position 2: if they work and the instrument cluster displays "P" or "N" for the gear position, then the engine should start when the key is turned to position 3. If it does not, then I would suspect a faulty ignition switch, though it could also be a faulty engine controller. I do not know how to discern which would be the faulty unit in this case, since the signal from the ignition switch to the engine controller is a CAN message.
I'm able to turn the key all the way to the third position with no problem. The vehicle is in park but it does not show on the digital display. I hooked up the iCarsoft (independent and dealer can't see me until next week) and have the following update.
This reader was not able to detect the engine ECU, traction control, etc. However, it was able to find and no errors showed for the EIS and the central gateway. I did, however get the following errors when reviewing the front left and right SAMs. What do you think this reveals? A CAN problem?
B1342 - Drivers side SAM circuit 15 input signal not ok
B1074 - Control module N64(EIS [EZS] control module) is not transmitting data on the CAN bus, OR No CAN data was received from the control module electronic ignition switch or Central gateway.
Interesting that both EIS and central gateway are mentioned. Yet, the scanner can talk to there and no error was found. Could a.bad engine ECU cause the EIS and the central gateway to not talk?
In theory I suppose the engine ECU could fail in a way that shorts both the high and low CAN communication lines to ground or the two of them together and thereby take down the engine CAN, but I don't think this would have any effect on the body CAN.
The B1342 code indicates that switched 12 VDC power is not reaching the SAM from the EIS (likely, in my opinion), or the SAM is faulty and not recognizing it. The other code is actually not a fault -- it's an "event" -- and as such is not of serious consequence. Note that neither code is relevant unless its status is "CURRENT".
Very interesting. By the way, those are current codes. I'm thinking that the problem may be CAN Bus C. Will get to any independent shop but in the meantime will try to clean and test the voltage for the CAN. I see that the X30/18 connector for CAN bus - C has built in circuits/chips at the connector. These seem to control to the ECM, traction control, ESP etc. The signal to wake comes from the EIS. Since the EIS is waking up the other systems such as lights, windows, instrument panel (controlled by CAN-B after wakeup signal from EIS), perhaps fixing wiring issue for CAN-C might fix the root problem. I don't see any obvious signs of corrosion, burning.
Here is the diagram of the CAN system showing that CAN-C wakes from EIS as well as the connector for CAN-C with the green wires.
In theory I suppose the engine ECU could fail in a way that shorts both the high and low CAN communication lines to ground or the two of them together and thereby take down the engine CAN, but I don't think this would have any effect on the body CAN.
The B1342 code indicates that switched 12 VDC power is not reaching the SAM from the EIS (likely, in my opinion), or the SAM is faulty and not recognizing it. The other code is actually not a fault -- it's an "event" -- and as such is not of serious consequence. Note that neither code is relevant unless its status is "CURRENT".
Very interesting. By the way, those are current codes. I'm thinking that the problem may be CAN Bus C. Will get to any independent shop but in the meantime will try to clean and test the voltage for the CAN. I see that the X30/18 connector for CAN bus - C has built in circuits/chips at the connector. These seem to control to the ECM, traction control, ESP etc. The signal to wake comes from the EIS. Since the EIS is waking up the other systems such as lights, windows, instrument panel (controlled by CAN-B after wakeup signal from EIS), perhaps fixing wiring issue for CAN-C might fix the root problem. I don't see any obvious signs of corrosion, burning.
Here is the diagram of the CAN system showing that CAN-C wakes from EIS as well as the connector for CAN-C with the green wires.
I foumd shorter wires for a remote start system that was installed by the prior owner. I did not know this existed but as I was tracking wires from the EIS I noticed it that it was installed in a series with the EIS. When this shorted it must have shut off the communication with CAN-C. Removed the remote start and it fired right up. I now have a break wear error visit workshop and a light sensor (probably from damaged CAN-B on passenger side).
Too bad since remote start could be useful. Thank you all for your help. I hope my experience helps someone else out.
Glad you found the problem. Did you happen to run a scan to see if you can scan the engine ecu and, if so, what codes you had stored? Just curious.
Mike
The only stored active codes on the ECU relate to the 2 pre-cat O2 sensors. Both show as faulty even though they have been replaced twice. This is likely a wiring/ground problem and not a new symptom. Unlikely that both are bad. Although I purchased the Bosch parts and have not tried buying the O2 directly from the dealer. My understanding is that Bosch makes them and Mercedes simply rebrands.
What is new is an error indicating the brake wear sensor. I'm also getting the red SRS light. Perhaps I unplugged one of the wires for the SRS as I was fidgeting around the dash . I will also check under the seats. I'm currently unable to communicate with the SRS module. I am able to talk to the other ECUs I couldn't before such as the ECM, ESP, Transmission, etc.
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