2007 S600 Crank, No start.
05-14-2016, 12:36 PM
#27
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Thread Starter
Yeah, if this were an issue that would show up in a scanner, I'd already have it fixed by now. It doesn't help that the fuel pump relay doesn't actually control the damn fuel pump. If I'd known there was a relay that controlled injector pulse but it wasn't called the injector relay, I'd be a few days further ahead on diagnosing this.
05-14-2016, 01:50 PM
#28
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Looks like a dead end. Apparently the fuel pump relay doesn't do a damn thing on the M275 engine. If I'm reading this schematic correctly, U779 is the part specific to the M275 engine, which is saying the fuel pump runs when its told by N118 which is the fuel pump module under the rear left seat, and it gets power from the common line to N10/2 which is the rear SAM. The only thing in between there is a fuse, which can't be blown otherwise the fuel pump wouldn't run, which it does.
In the M273 engine (S550) the fuel pump relay energizes from the ECU and powers the fuel pump, the rear SAM is shared between the S550/S600, but it looks like the fuel pump relay doesn't do anything in the S600, but it should still have 12V at pin 30, even though its not used, simply because the two cars share the same Rear SAM. Unless I'm reading this wrong, in which case someone please correct me.
I'm going to try to find what actually supplies power to the injectors, and trace back from there, will update if I find anything.
Edit: The fuel injectors are fed by the engine computer, and again if I'm reading this right, it looks like they get their information from....the throttle valve actuator. If the TB is shot, the engine computer doesn't know how to pulse the injectors. I wish the damn throttle body had gotten here Friday, but I guess I'm done diagnosing until I can rule out the throttle body as the root of the problem. Too many things are pointing to it at this point.
Last edited by GPrime2; 05-14-2016 at 02:08 PM.
05-16-2016, 08:52 AM
#29
Looks like a dead end. Apparently the fuel pump relay doesn't do a damn thing on the M275 engine. If I'm reading this schematic correctly, U779 is the part specific to the M275 engine, which is saying the fuel pump runs when its told by N118 which is the fuel pump module under the rear left seat, and it gets power from the common line to N10/2 which is the rear SAM. The only thing in between there is a fuse, which can't be blown otherwise the fuel pump wouldn't run, which it does.
In the M273 engine (S550) the fuel pump relay energizes from the ECU and powers the fuel pump, the rear SAM is shared between the S550/S600, but it looks like the fuel pump relay doesn't do anything in the S600, but it should still have 12V at pin 30, even though its not used, simply because the two cars share the same Rear SAM. Unless I'm reading this wrong, in which case someone please correct me.
I'm going to try to find what actually supplies power to the injectors, and trace back from there, will update if I find anything.
Edit: The fuel injectors are fed by the engine computer, and again if I'm reading this right, it looks like they get their information from....the throttle valve actuator. If the TB is shot, the engine computer doesn't know how to pulse the injectors. I wish the damn throttle body had gotten here Friday, but I guess I'm done diagnosing until I can rule out the throttle body as the root of the problem. Too many things are pointing to it at this point.
Sorry for the basics but sometimes it is the issue
05-18-2016, 10:23 AM
#30
I've tried as much diagnostic work as I can before posting in hopes that someone knows more than I do about these cars. I have a 2007 S600 that has been an absolute joy to drive until recently it started having intermittent starting issues. I believe there is an issue with the throttle body, as the throttle angle reads 8.6 degrees with my foot off the throttle (acceptable range per my scanner is 0-2.4 I believe). My main question is can the electronic throttle body issue cause a no start condition on this car?
I've eliminated spark from the equation by spraying starter fluid directly in the TB and it starts. I removed the fuel pump and bench tested it, it runs correctly. The fuel pressure reading from the scanner is in the 40psi range, raising to the mid 50s during starting. There is fuel at the rail, I have not tested the actual pressure at the rail, I've only depressed the schrader valve to verify fuel spraying out, the pressure seems consistent with the pressure readings. I've tested injector pulse at the injector connectors, they seem to be working correctly. I've also changed the crank position sensor just as preventative maintenance and to rule it out as a possible culprit. Any ideas?
I have a Maxidas DS708 available to scan any system, so if anyone needs a specific reading to help with diagnostics, I'd be happy to rescan the car. A few other things I've checked, cam position hall sensor is reading correctly, crank speed is reading correctly, batteries are both fully charged and crank is strong.
I've eliminated spark from the equation by spraying starter fluid directly in the TB and it starts. I removed the fuel pump and bench tested it, it runs correctly. The fuel pressure reading from the scanner is in the 40psi range, raising to the mid 50s during starting. There is fuel at the rail, I have not tested the actual pressure at the rail, I've only depressed the schrader valve to verify fuel spraying out, the pressure seems consistent with the pressure readings. I've tested injector pulse at the injector connectors, they seem to be working correctly. I've also changed the crank position sensor just as preventative maintenance and to rule it out as a possible culprit. Any ideas?
I have a Maxidas DS708 available to scan any system, so if anyone needs a specific reading to help with diagnostics, I'd be happy to rescan the car. A few other things I've checked, cam position hall sensor is reading correctly, crank speed is reading correctly, batteries are both fully charged and crank is strong.
05-18-2016, 09:14 PM
#31
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Thread Starter
I gave up, the throttle body didn't fix it, injectors still aren't getting pulse, I checked the wiring harness for the injectors, power and ground are getting there so I'm guessing it's either the engine computer or something stupid I forgot to check. Either way, I talked to the head tech at my local Mercedes dealership, told him what I'd done already, and he wants to take a look at it. I figure their computers and techs are better than I am at this, so we'll see what happens. I'm towing it down there next Tuesday, I'll update the thread when I find out what the problem was.
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mercedesbenzs55 (05-24-2016)
05-23-2016, 09:17 PM
#34
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Going in tomorrow to be tested, already changed the crank position sensor, and I'm not going to replace an ECU on this car before being 100% sure that's the problem. I'm totally ok with paying an hour or two of diagnostic time at the MB dealership to make sure that's the issue, we'll see what it ends up being, whatever it is it's beyond my capabilities to figure it out.
Edit: you said harness, i doubt that's the problem, I'm getting a valid crank speed reading from the scanner, which (correct me if I'm wrong) is pulled from the CKP.
Edit: you said harness, i doubt that's the problem, I'm getting a valid crank speed reading from the scanner, which (correct me if I'm wrong) is pulled from the CKP.
05-25-2016, 09:29 PM
#38
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Thread Starter
MB Tech called today, he's chasing a transmission code as the possible issue, I have it written down at my shop but it's basically saying the torque converter is locked, which could be causing the engine not to get enough RPM on cranking to signal the injectors to fire. As a favor he's unbolting the torque converter and trying to start the engine tomorrow so I don't have to tow it back to my shop and do what'll probably take 20min of time. I'm not looking forward to pulling the trans to swap TCCs but if I can get a definite answer, it'd probably be the happiest trans swap I've ever done lol.
05-25-2016, 09:49 PM
#39
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2015 S550
MB Tech called today, he's chasing a transmission code as the possible issue, I have it written down at my shop but it's basically saying the torque converter is locked, which could be causing the engine not to get enough RPM on cranking to signal the injectors to fire. As a favor he's unbolting the torque converter and trying to start the engine tomorrow so I don't have to tow it back to my shop and do what'll probably take 20min of time. I'm not looking forward to pulling the trans to swap TCCs but if I can get a definite answer, it'd probably be the happiest trans swap I've ever done lol.
05-25-2016, 09:52 PM
#40
Man this would be a bizarre one.
I know how you feel about the "If I only knew the answer" type thing. You definitely paid your dues with this one.
Guess what I don't understand is how the TC is locked up when cold. Are they getting TC speed sensor codes on this?
I know how you feel about the "If I only knew the answer" type thing. You definitely paid your dues with this one.
Guess what I don't understand is how the TC is locked up when cold. Are they getting TC speed sensor codes on this?
05-26-2016, 11:14 AM
#41
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Thread Starter
They're not pulling the trans (I wish I had MB techs willing to that kind of favor for me lol) they're just disconnecting the tcc from the flex plate (access plate under the bell housing, usually 4-6 bolts) and trying to start the car without the load of the trans on it. I don't think that's going to be the issue but I hope it is just so I know for sure what the problem was. At that point I'll tow it back to my shop and drop the trans.
Edit: the code he found was 2783: torque converter lockup clutch excessive power consumption
Edit: the code he found was 2783: torque converter lockup clutch excessive power consumption
Last edited by GPrime2; 05-26-2016 at 11:17 AM.
05-26-2016, 11:50 AM
#42
They are clutching at straws- are you hearing the crank to be much slower than normal? Record a sound clip and post if in doubt. It has to be a really slow crank for the ecu to not pulse the injectors. Like reaaaaaaaly slow. You would have noticed something that bad.
I still think it is ecu. Or something really stupid - fusable link, missing ground, etc.
I still think it is ecu. Or something really stupid - fusable link, missing ground, etc.
05-26-2016, 11:03 PM
#44
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Thread Starter
ALX - yes I think so too, but they did give me an idea that I hadn't thought of, the crank speed is reading low, like 150-200rpm on crank. Not sure where that leads me next but we'll see if the techs come back with anything different after unbolting the TCC
KN51 - no it's not a p-code, it's a mercedes error code. They didn't call me today, I'm hoping this gets under their skin and becomes a pet project to figure it out.
The slow crank speed reading has me thinking maybe he's onto something, it didn't sound like it was cranking slower, so maybe it's electronic. I always assumed the CKP read crank speed, but is there anything else in these engines that reads crank speed?
KN51 - no it's not a p-code, it's a mercedes error code. They didn't call me today, I'm hoping this gets under their skin and becomes a pet project to figure it out.
The slow crank speed reading has me thinking maybe he's onto something, it didn't sound like it was cranking slower, so maybe it's electronic. I always assumed the CKP read crank speed, but is there anything else in these engines that reads crank speed?
06-01-2016, 07:14 PM
#45
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Final Update: It's running again, turned out there was a burnt wire in the front SAM in the z-pack, it wasn't fully burnt so it was giving about 3.5V to several powertrain components including the injectors and the ignition module. (which is likely what I was seeing with the injectors, and why it only sputtered on starter fluid). The tech cleaned off the wire and made a clean connection, it starts and runs every time now. As a precaution, I'm going to be replacing the ignition module since he believes it's drawing too much amperage which is what caused the burnt wire in the first place. At this point, I'm inclined to believe what he says.
He told me he had ~8-9hrs in diagnostics in it, but only charged me for 5hrs at $100/hr so I was out for $500 which I can't say is all that bad considering how confused I was when I brought it to them. Kudos to the team at Mercedes Benz of Rochester (NY) for getting her running again!
He told me he had ~8-9hrs in diagnostics in it, but only charged me for 5hrs at $100/hr so I was out for $500 which I can't say is all that bad considering how confused I was when I brought it to them. Kudos to the team at Mercedes Benz of Rochester (NY) for getting her running again!
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alx (06-01-2016)
06-01-2016, 10:02 PM
#46
Good find. I have seen ignition modules go bad and burn fuses. However yours is apparently half- bad and drawing more current thus raising amperage and heating up wires. One more sneaky gremlin for the books. Thanks for the update.
Oh, and the official rate for authorized mb dealer in the states is $130-145... You got a discount
Oh, and the official rate for authorized mb dealer in the states is $130-145... You got a discount
06-02-2016, 10:11 PM
#47
Member
Thread Starter
Good find. I have seen ignition modules go bad and burn fuses. However yours is apparently half- bad and drawing more current thus raising amperage and heating up wires. One more sneaky gremlin for the books. Thanks for the update.
Oh, and the official rate for authorized mb dealer in the states is $130-145... You got a discount
Oh, and the official rate for authorized mb dealer in the states is $130-145... You got a discount
10-08-2019, 10:23 AM
#49
Senior Member
No start condition with the identical issues...
Final Update: It's running again, turned out there was a burnt wire in the front SAM in the z-pack, it wasn't fully burnt so it was giving about 3.5V to several powertrain components including the injectors and the ignition module. (which is likely what I was seeing with the injectors, and why it only sputtered on starter fluid). The tech cleaned off the wire and made a clean connection, it starts and runs every time now. As a precaution, I'm going to be replacing the ignition module since he believes it's drawing too much amperage which is what caused the burnt wire in the first place. At this point, I'm inclined to believe what he says.
He told me he had ~8-9hrs in diagnostics in it, but only charged me for 5hrs at $100/hr so I was out for $500 which I can't say is all that bad considering how confused I was when I brought it to them. Kudos to the team at Mercedes Benz of Rochester (NY) for getting her running again!
He told me he had ~8-9hrs in diagnostics in it, but only charged me for 5hrs at $100/hr so I was out for $500 which I can't say is all that bad considering how confused I was when I brought it to them. Kudos to the team at Mercedes Benz of Rochester (NY) for getting her running again!
So far I have not found any burned wires in this location perhaps I have to try and find one somewhere else? for now I'm puzzled and hopefully somebody will chime in with other ideas or suggestion to solve this.
Best H
