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1998 C43 AMG, 1983 300TD, 1983 300CD (deceased)
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7 Posts
Discussion Starter #1
Howdy!

So, we're a classic MB garage. 300SL and 300 limos our specialty. We service only a few contemporary MB vehicles, although most of us drives one (1998 C43 AMG, here). We have a Chinese C4 multiplexer, as well as an iCarSoft handheld tester. Both have worked well for us in the past.

About. a month ago, our insurance agent brought in her 2006 ML350 4matic for engine management issues (rough running at low throttle). We diagnosed intake manifold air flap issues (both the control levers and the flaps were disintegrated). She agreed to a factory reman intake manifold, for $$$, which we ordered from MB and installed without issue.

Now here's where it starts to get weird.

After reassembling things, we reconnected the battery, cleared codes, and the car started right up. We pulled it out of the workshop, and it suddenly threw a warning: red display, battery icon, "Visit Workshop". We checked the alternator output at the terminal strip over the right front wheel well, and it read 14.2V, so we restarted the car and went out for a test drive.

Car ran fine on the test track, and we parked it for the night.

When we got in the next day, we wanted to rearrange the parking lot, so we started up the ML350, backed it out of its spot, drove forward about 10 feet, and the car completely shut down. Display read "Drive to workshop without changing gear". (Which we could not do anyway — because this f*&@# car cannot be shifted into neutral with the computers offline. MB sells a "kit" for that, which is literally four big roller bearings that bolt between the hubs and the wheels. I am not making that up. Todays Mercedes-Benz is not the company of yesterday, that's for sure.)

Anyway, I got the DAS system out, plugged it in, and discovered that, out of nowhere, all the high-speed CAN-C nodes were not communicating:

ME 9.7 - Motor electronics 9.7
- ! -
Transmission
- ! -
ESP - Electronic stability program
- ! -
AB - Airbag
- ! -
SCM [MRM] - Steering column module
- ! -

The ISM module had entirely dropped off the list of available modules.

There was simply no communicating with any of these modules, with either the faux-MB system or the iCarSoft handheld. And, without being able to communicate with the ISM, we could not even shift the car into neutral. So there it sat, in the middle of the parking lot.

After much screwing around, I accidentally tried communicating directly with the ISM module with the ignition off, using the iCarSoft handheld, and this, bizarrely, allowed me to clear the ISM errors, and shift the car into neutral.

In addition, the DAS system warned that the CGW needed to be recoded. We have no online recoding access, of course, so I followed the prompts to recode locally. Received a few errors during that process but it completed.

After several days poring over wiring diagrams, I concluded that the common element in the CAN-C communication faults was the ECU, so I sent ours, with a used module from LKQ, in to a Chicagoland reprogrammer, who was able to transfer our authorizations to the junkyard unit, for more $$$.

The reprogrammed ECU now communicated with our diagnostic systems, and I was able to clear some codes. But the car still could not be started.

The new ECU was complaining that it could not communicate with the alternator, and this made sense given the battery error we saw when the car was first run post-repair, so we next installed a new Bosch brush pack / LIN-BUS transmitter, and that code went away.

But the car still will not start.

As we stand now:
  • Car can be shifted but does not start.
  • Throttle body servo can be heard at engine when key is in drive position.
  • AB / SDS module can only be talked to with the key off.
  • ESP module cannot be talked to at all.
  • Multiple modules throw CAN communication errors.
  • ECU communication is intermittent using iCarSoft handheld tester.
This whole situation is absolutely baffling, considering all we did to the car was to gently relocate ECU, cables, and such from the top of the intake manifold and then put them back — and the car ran fine after we did that. It only failed the next day.

Help!

Thank you, community, for any help you might be able to provide. I can't imagine we're the only ones that have encountered this suite of problems. We're facing dire consequences if we cannot get this ^$&#* thing mobilized.
 

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Coupe/Convertible Forums Moderator
CURRENT: 2011 SL550 FORMER: C300, ML350, CLK550 Cabriolet, C240, ML320, 300TD
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20,034 Posts
You had to unplug the ECU wiring harness to remove the manifold. I suspect the issue lies in that. Maybe the connectors or wiring were brittle and something broke or you bent a pin. I'd check there.
 
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1998 C43 AMG, 1983 300TD, 1983 300CD (deceased)
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7 Posts
Discussion Starter #3
Thanks!

The harnesses were the first thing I thought of, especially as we found traces of rodent habitation in the engine bay, I’ve unwrapped both harnesses and checked for damage, checked continuity in all 15, 30, and ground pins as well as the LIN line from the alternator, and inspected the ECU plugs and jacks as well.

Unless I’m mistaken, the ESP and AB / SRS modules have their own connections to the CAN backbone, which does not run through the ECU harness. And it’s those that are behaving the most bizarrely.
 

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Outstanding Contributor
02 ML320 06 ML500
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17,274 Posts
Take a voltage check on the main battery, should be 12.7v.

Then take a voltage check on the Auxiliary Battery, should be 12.7v. The Aux. Batt. is there for your present problem. While the conectors are still in place,Introduce 12v to positive cable and ground to negative cable.

This will allow you to put the selector lever in NEUTRAL so you can push the car into the shop.
 

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Outstanding Contributor , SDS Guru
1998 MB E300TD, 1997 MB E36 AMG, 2001 MB E55 AMG
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4,909 Posts
First thing first.

Since you have SDS, that's a big help.

Check CGW, check DAS in ISM, check DAS in ECU, check DAS in EIS and report back. Be better if you could post pics of the DAS in those modules.

The CGW and ISM are a known issue, and both will cause no start, since CGW acts as the router and the ECU, EIS, TCM and ISM must communicate before car is allowed to start. If none of these modules can talk to each other, no start.
 

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Registered
1998 C43 AMG, 1983 300TD, 1983 300CD (deceased)
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7 Posts
Discussion Starter #6
Take a voltage check on the main battery, should be 12.7v.

Then take a voltage check on the Auxiliary Battery, should be 12.7v. The Aux. Batt. is there for your present problem. While the conectors are still in place,Introduce 12v to positive cable and ground to negative cable.

This will allow you to put the selector lever in NEUTRAL so you can push the car into the shop.
Yeah, the batteries are both fine. The shifting issue had to do with the ISM being offline. It now works.
 

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Registered
1998 C43 AMG, 1983 300TD, 1983 300CD (deceased)
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7 Posts
Discussion Starter #7
First thing first.

Since you have SDS, that's a big help.

Check CGW, check DAS in ISM, check DAS in ECU, check DAS in EIS and report back. Be better if you could post pics of the DAS in those modules.

The CGW and ISM are a known issue, and both will cause no start, since CGW acts as the router and the ECU, EIS, TCM and ISM must communicate before car is allowed to start. If none of these modules can talk to each other, no start.
Thank you!

I do suspect the CGW, as DAS has prompted a CGW reflash twice. I don’t have online DAS access, so I have had to accept the local firmware option. It flashes but throws some errors in so doing. I wonder if it is simply not coding in the modules that appear missing (though what on earth would make the Airbag module only communicate with the key off?!)

I’ll step through the DAS stages on Monday, print each to PDF and post.
 

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Outstanding Contributor , SDS Guru
1998 MB E300TD, 1997 MB E36 AMG, 2001 MB E55 AMG
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4,909 Posts
You don't necessarily need to do initial start, that requires online account. And right now online access isn't working for anyone except dealers.... This is worldwide. So even if you found someone who could log in for you, still no online access for the moment.

Try to code it through the adaptation, but if that doesn't work, then plan on getting a new or used CGW. Like I said, known issue, and the CGW is the router for the canbus comm lines. I believe all three or four canbus converge at CGW.
 

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1998 C43 AMG, 1983 300TD, 1983 300CD (deceased)
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Discussion Starter #9
Right! That’s what I’ve done, and the CGW wasn’t throwing any codes last I checked. But I will check again Monday.

Do you know off the top of your head where it’s located? Does the seat have to come out to get at it?
 

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Outstanding Contributor , SDS Guru
1998 MB E300TD, 1997 MB E36 AMG, 2001 MB E55 AMG
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Yup, driver seat has to come out.
 

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W163 Crash Test Driver
2008 ML350 (Me!), 2010 GLK350 (Wife), 2003 ML-350 (Deceased)
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1,755 Posts
I had identical, bizarre symptoms a few years ago when a mouse chewed some of the CAN wires coming off the ECU.

Here is the post.
 
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1998 C43 AMG, 1983 300TD, 1983 300CD (deceased)
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7 Posts
Discussion Starter #14
Here are the procedures to remove the CGM
Thanks! I’ve got it all downloaded already. (Amusingly, our LKQ rep called us today to ask where the module we purchased is located in the vehicle, and how to remove it.)
 
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