Oh, this is going to be a doozy

nickb2

Wrench. Diagnostic Tech.
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Messages
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Location
St-Hyacinthe, Quebec, Canada
Make
mercedes benz
Model
gkl 350
Year
2011
Miles
221k km
Engine
v6 gas
Apparently I have this car for a whole week. So this is a cool thread to start some brain storming.

Initial complaint on work order translates like this.

No start, have to tries many times, eventually it starts. Needs oil change, and check link kit in front,

Hand written, check slow leak left front
 

nickb2

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This is a straight low and high speed can bus issue for sure, and it is elusive.

I will keep posted with codes, cuz when I first scanned the car, every module had a can fault or miscommunication U code.

But was able only to see that the client was loosing front right wheel due to, NOT link kits, but a SEVERELY loose lower ball joint

Literally, I counted 23 or more can and U codes.

Most of which of all, was a gateway code. SO I narrowed down on that, and then end of shift came. But still got time, to snap sleep time for can, as I knew it would dies in 30 mins and could go home knowing my stuff didnt have to be lit all night, especially with the power shut we had .
 

nickb2

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So next step, either rip apart car disconnect each and every module and wait and see. No, there is a better option. Time and research.
 

nickb2

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Tiny update, new problem.

This morning, suv was still in my bay, went to start it, yes, no start, f with it for a long time, finanly start, now no more gears expect park and neutral.

No time to f with it, had other shyte to do. So we pushed it outside, so even the tranny module is no see high and low. Interesting, gives me more info that client didnt give me before. He just said it takes forever to get the key to start the car. Well now we know for sure, this is going to be a very hard trace to find, but the more info I accumulate, the better.

So pushing it while live was a good idea, no reboot done, just studying what the can line is doing to system, and which module is the gateway.

That is key, I need to find the gateway module. And my databases are not showing it. But I do have the wiring diagrams and also the can comm lines also.

SO a bit perusing those diagrams should in principle help me narrow down which modules that are not gateway modules to disconnect till full function of can line, then reconnect 1 at a time till can failure happens, at that point, it is down that module, or it wiring and grounding..
 

nickb2

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The principle behind the above approach is easy to understand, once you know how BUS lines work. If you are NOT a host module, such as a door module, by definition, the rest of the network is designed to work without your input.

But lets say a ecm or tcm, BCM etc is on the fritz or some of its associated wiring or chassis grounds etc is bad, it WILL cause a global network shutdown or limited network function.

But by design, a radio module, or a moonroof module, or even an ac module are designed to not interrupt network.

But they all interact with the network and can possibly cause noise which gives way to same result. SO by eliminating those one at a time till function is restored, it pins down greatly and save alot of time.

Using a scope is great for this, you can see the communication restore, the baud rate smoothed out and bingo.
 

billr

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Honestly, that CAN stuff and analyzing hex-code PID data is beyond me. Microchip is certainly a good name in the electronics world, so any product they offer is creditable. I tried looking at the "examples" of data display, but those were zipped and even when extracted seemed to need an install of the SW; so I aborted the attempt to look. I prefer demos/examples that "self run"; even just some screen-shots of typical data the SW can display. The $100 price seems reasonable.
 

nickb2

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I rather listen to my mom

Bullshyte is like a guy like me.

Today, I understood just one thing. Always listen, and never underestimate the power of your peers
 

nickb2

Wrench. Diagnostic Tech.
Joined
Nov 22, 2008
Messages
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Points
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Location
St-Hyacinthe, Quebec, Canada
Basically, most ppl here need to now, whatever they think, we are all connected, whether yo want it or not, so on this, my song selection of last ditch beer effort.

 
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