ML270CDI No Start

[Laurie in oz]

Hi all.
My much liked Merc. is off the road.
The key turns OK to the on position, the warning lamps light except the pre-glow one, then after two Seconds the engine cooling fan runs to full speed and that is as far as I get. The key will not turn further.
Fortunately for me, the first occurrence was under cover at work shortly after unloading. I restarted to move the vehicle. That start was normal but the engine shut off and the fan kicked in right after. I attempted another restart several times but no joy. Just the fan.

I connected a scanner and it showed problems related to the ECU and CAN Bus Communication plus something like "Engine temperature implausible". A look at live data showed an engine temperature over 2800 degrees. The in-dash gauge was showing about 65 degrees and there has not been any loss of coolant so definitely "implausible".

So does the ECU get its temperature information from some other sensor?
Such as the "oil sensor" on the lower left side of the sump. It has three wires to so might it be sensing temperature as well as level???

Any clues much appreciated, especially if they save me a truck-away.
Laurie.

 

[LostKiwi]

Have you tried clearing the codes and attempting a restart and seeing which codes come back?

 

[Laurie in oz]

Have you tried clearing the codes and attempting a restart and seeing which codes come back?

Yes bembo449, thanks for your response.
The same codes come right back.
Car purchased August last year, the scanner in December.
Cleared many (over 40) old codes at that time.
Only the CAN bus errors came straight back in but the car was driving fine until the above.
The scanner is now not always able to establish communication.

After many tries the car started and ran three times since the cutoff but I have been afraid to take it onto the public road.
I drove it around the 25 acre property for about 10 minutes the first time with no problem.
Nearest Mercedes Service Centre is 25 minutes away.
Battery is unknown age but cranks well when it does.

 

[LostKiwi]

Ok in that case have you tried unplugging ECU connectors, spraying with switch cleaner (do NOT use WD40/GT85 or similar products - only use proper contact cleaner or preferably switch cleaner)?

 

[Steve@Avantgarde]

Basically its lost a CAN feed from the engine ECU which is why the fan is running flat out. Its in emergency running.

Usual problems with MLs doing this is the AAM module breaking down. You will need STAR to do a full test step procedure.

 

[Laurie in oz]

AAM has B1 040-001 Stored. Can bus fault in communication ESP/ETS if no malfunction ignore.
and B1 040-005 Stored. Can bus fault in communication N1 0/1 Extended Activity Module EAM.
Other details on the AAM.
ECU info Control Unit AAM
MB Number 163 545 25 32
Supplier Kostal
Hardware Status 14/99
Software Status 31/99
Diagnosis Identifier 0/6
Production Day 02
Production Year 2000
No events in Memory

Car started after I plugged in the scanner again.
Now running a full scan.
If that completes I will see if I can get it home.
Your help so far much appreciated.
.....Later.....
Drove home like normal, about 20 minutes. (With the Scanner connected.)
No new fault codes.
Set the scanner for "Live Data" and to test the CAN bus. (Car sitting with engine idling.)
It found 611 the Traction systems: 612 the Transmission control: 613 the Drive Authorization System: 615 the Air Conditioning: and 616 the Instrument cluster. All except the instrument cluster showed "N/A" for one to five seconds randomly for maybe 2% of the time.

 

[Laurie in oz]

Ok in that case have you tried unplugging ECU connectors, spraying with switch cleaner (do NOT use WD40/GT85 or similar products - only use proper contact cleaner or preferably switch cleaner)?

How about "DeoxIT?
It is a "Contact Cleaner Enhancer and Protector".

 

[LostKiwi]

How about "DeoxIT?
It is a "Contact Cleaner Enhancer and Protector".

Not familiar with it but (aside from being hellishly expensive!) it looks fine.
I normally use Servisol products.

 

[Steve@Avantgarde]

The CAN network is obviously down which is why its flagged the ESP, it probably uses the same CAN buzz bar.

The car needs STAR really.

 

[television]

There are about 4 fuses on the K4 ECU, as above STAR could help, but do check those fuses.

 

[Westheath]

If the can bus box is down reset by removing the vehicle battery/s
or physically remove the connectors from the unit and reset.

MB Star will not always sucessfully diagnose the can bus system as it relies on information from it,
bit like trying to diagnose a internet fault at your home office
with no isp providing packet data.