Don't know much about the W210, have you considered the alarm system?
Also, the ignition switch behind the dash, can cause this kind of trouble too. How much weight is on that key chain?
Once upon a time I owned a VW Golf that had a similar symptom. Turned out to be the ignition switch (electrically not mechanically).
Perhaps there is a relay in the alarm system that seperates the chassis ground.
To verify this you have to know where on the connector the Battery voltage should be present and measure from there to the battery neghative terminal directly.
If there is nothing showing up, investigate closer in the ignition switch area!
If there is something, take a reading across the battery terminals, make a note of it. Then measure the connector pin again to battery negative. If there is any significant difference to be seen, you are dealing with a high impedance
on B+ caused by a relay with burned contacts, or the list could go on and on.

I guess the fan is running because the ECU is not energized. Normally the ECU switches a relay open so the fans don't run until they should. It's a fail safe to keep the coolant temperature down in case??? Oooops, you said this already!

One thing is for sure, the electronics lost its return to battery!! The source is very difficult to locate! Troubleshooting must be done very systematically!

Since you have the main power relay module already out, have a close look at the pins on the solder side. This stuff is soldered automatically, but the pins are relatively large and require just about the right amount of heat to be flow soldered.
Wickle a little on the pins observing the solder side, better yet use a beeper and see if all pins beep to the PCB (Printed Circuit Board) not to the other side of the pins, actually to the trace on the board, measuring the solder joint too.

I have found intermittently open pin contacts and resoldered them. It seems that this is common. You'll only know if you beep it to the trace.


Sorry about this miserable experience out in the cold!
Sounds like me, if the s%$#@t hits the fan there is always, at least two or three other things going really bad!

Hope that gives you a few more Ideas, if you haven't found the problem already!

__________________
Mostly, I don't know notin, I just know where to look.
I am looking back, to over 30 years in Electronics Design.
Electrons don't care if they move in a car, computer or relay!

95 W124 E320 M104.992 - Because, I love to repair, naaaah!
Over 221,000 Miles
Cheers,
Norbert

This sounds like a wiring failure somewhere or the K40 relay bank has gone bad.

__________________
2012 BMW X5 (Beef + Granite suspension model)

1995 E300D - The original humming machine (consumed by Flood 2017)
2000 E320 - The evolution (consumed by flood 2017)

Ok,

The EIS system (immobilizer) is functioning properly. The lock and unlock functions work correctly and EIS recognizes the key because it allows a start command to be issued and executed. Changing the CPS (of course) had no effect, because the ECU is offline, but I changed it anyways just for good measure.

The car is a one-owner in pristine condition. There is not a single broken electrical connector on the car, no aftermarket radio or alarm system. There is no damage to any of the wiring.

The K40 relay looked perfect inside as did the ECU with no odor or visible signs of short circuits.

The consensus of the technicians I have spoke with who have W210 experience is a failure of the ECU components internally. This is difficult to prove, because you cannot re-code a used ECU to test this hunch. Only a new ECU can be coded to the car. Many people sell used ECU's. and are unaware of this issue.

I really can't complain. This is the first time in 35 years of driving that I have ever had to be towed back in.

On a lighter note, my BMW E34 is a fantastic car and it did a lot of work this weekend ferrying parts and tools back and forth...

__________________
Did you just pass my 740 at 200 kmh in a 300SD?????

1978 300SD 'Phil' - 1,315,853 Miles And Counting - 1, 317,885 as of 12/27/2012 - 1,333,000 as of 05/10/2013, 1,337,850 as of July 15, 2013, 1,339,000 as of August 13, 2013



100,000 miles since June 2005 Overhaul - Sold January 25th, 2014 After 1,344,246 Miles & 20 Years of Ownership

Did you check all the power / ground pins at the ECU harness?

Check for power at the pos side of the injectors.

If you are getting power to the ECU , crack it open, follow pins to the power to the board check for power / ground. There should be a voltage regulator, largish capacitor and MOV inside, check for power here.

Yes, power is present, but no modulated ground signal...

__________________
Did you just pass my 740 at 200 kmh in a 300SD?????

1978 300SD 'Phil' - 1,315,853 Miles And Counting - 1, 317,885 as of 12/27/2012 - 1,333,000 as of 05/10/2013, 1,337,850 as of July 15, 2013, 1,339,000 as of August 13, 2013



100,000 miles since June 2005 Overhaul - Sold January 25th, 2014 After 1,344,246 Miles & 20 Years of Ownership

First of all, keep in mind that this is a one-owner W210 with only 100,00 miles, with stock stereo and alarm and no broken electrical connectors or other evidence of tampering. An originla California car, bought new at MBZ of Palm Springs, it has no signs of rust or corrosion anywhere on the vehicle.

After reviewing the wire diagram, and consulting a W210 platform expert here at our firm, I discovered that power to the ECU is supplied by connector 'E' pin 5-6 of the K40 Relay. Fuse F4 (40amp Maxi) was hot vut (3) of the (5) 15amp fuses on the K40 were dead - clearly a bad K40, right???

Swapped in a known good K40 and instantly found voltage present at 'E' connector and fuses F-1 through F-6 were now energized. However, the car still cranked but would not start.

Ok, so we know now for a fact the K40 is bad, but what else is wrong???

I then checked the voltage signature and found the battery to be 12.72 and 'E' connector pins 5-6 AND Fuses F-1 through F-6 (excluding the F-4 maxi fuse) had only 8 volts!!!

A check of the wire diagram showed a multi-point ground in front of the ECU 'Nest' and it looked perfect, with no sign of moisture or corrosion. However, this ground had 190-200 ohms of resistance.

I took the blades off the stud and still no visible sign of corrosion. This car doesn't even have dust in the engine compartment, because it has always been (and still is) garage kept. However, once I treated each blade with dielectric grease the resistance value disappeared and both the 'E' connector and fuses registered battery voltage.

The M104 started immediately.

So, looking back over the past 30 days of ownership, my wife has complained about pushing the throttle at times with no acceleration and a bizarre intermittent 'misfire' or 'roughness' while idling at a traffic light.

2 weeks ago, I drove the car (for the first time) and noticed a slight misfire at idle with a corresponding 'puff-puff' in the exhaust. I also got a CEL and code for cylinder misfire. In response, I changed to a new set of OEM spec spark plugs and this problem seemed to go away. However, the more I think about it, the more I think the ground insulation and K-40 issues are the true cause of these anomolies.

The car always ran great, but it is noticeably smoother and more powerful now.

So, to the $3,000 purchase price of this W210, I now only have to add a brand new MBZ K40 Module for $147.95. What a blessing!!!!

Hope this helps someone with a similar issue...

Attached Thumbnails

       

__________________
Did you just pass my 740 at 200 kmh in a 300SD?????

1978 300SD 'Phil' - 1,315,853 Miles And Counting - 1, 317,885 as of 12/27/2012 - 1,333,000 as of 05/10/2013, 1,337,850 as of July 15, 2013, 1,339,000 as of August 13, 2013



100,000 miles since June 2005 Overhaul - Sold January 25th, 2014 After 1,344,246 Miles & 20 Years of Ownership

Told ja it was a K40 module issue. - anyway - its good that your car is in service again.

I helped a guy troubleshoot a similar issue across the world via skype. lol

anyway. How come you have a 104 in there in a 99-2000 model. The last cars with this were 1997.

__________________
2012 BMW X5 (Beef + Granite suspension model)

1995 E300D - The original humming machine (consumed by Flood 2017)
2000 E320 - The evolution (consumed by flood 2017)

Grounding is always the first thing I check. In fact, I'll go as far as loosen and retighten the grounds in the engine compartment. I don't care where the car is from, any time a metal gets wet, corrosion is suspect. It doesn't take much chemical contact to start the corrosion, and it will be where you cannot see it. (Inbetween grounding washers)

I also firmly believe that a good majority of repairs (r/r fuel pump, or this valve/sensor) actually get fixed by disturbing the electrical connection, until it happens again and the owner things it's a lemon,,,

__________________
Closing the store
Benzbonz.biz on your smart phone or tablet.

Great to see a happy ending to an unfortunate situation.

By the way, the M104 was the inline 6 that ended in 1997 in the E320 and 1999 in the S320.

You have a M112 V6.

Love the pics. That interior is ultra clean.

__________________
Paul S.

2001 E430, Bourdeaux Red, Oyster interior.
79,200 miles.

1973 280SE 4.5, 170,000 miles. 568 Signal Red, Black MB Tex. "The Red Baron".

Can you tell us where the K40 is located and maybe provide a photo? I am having issues with a '98 E300, and that was said to be the usual suspect.....Rich

__________________

All Diesel Fleet
1985 R107 300SLD TURBODIESEL
2005 E320 CDI (daily)

LOTS of parts for sale!


EGR block kit
http://www.peachparts.com/shopforum/diesel-discussion/355250-sale-egr-delete-block-off-plate-kit.html

1985 CA emissions 617 owners- You Need This!
Sanden style A/C Compressor Mounting Kit for your 616/ 617 For Sale + Install Inst.

Sanden Instalation Guide (post 11):
http://www.peachparts.com/shopforum/diesel-discussion/367883-sanden-retrofit-installation-guide.html

Paul, Doktor Bert has an inline 6 in his 210 automobile. Look at the engine compartment picture again.

__________________
Fred Hoelzle

Glad your problem is solved, but dielectric grease is non-conductive and should generally not be used at the ground connections.

__________________
Prost!

The K40 is the unit in the front of the stack with (1) 40amp Maxi-Fuse and (5) 15 amp fuses...

Attached Thumbnails

 

__________________
Did you just pass my 740 at 200 kmh in a 300SD?????

1978 300SD 'Phil' - 1,315,853 Miles And Counting - 1, 317,885 as of 12/27/2012 - 1,333,000 as of 05/10/2013, 1,337,850 as of July 15, 2013, 1,339,000 as of August 13, 2013



100,000 miles since June 2005 Overhaul - Sold January 25th, 2014 After 1,344,246 Miles & 20 Years of Ownership

edit:

the doc already got it.

__________________
2012 BMW X5 (Beef + Granite suspension model)

1995 E300D - The original humming machine (consumed by Flood 2017)
2000 E320 - The evolution (consumed by flood 2017)

You're right. I thought he said he had a '99 or '00 E320 in a previous post.

His car is actually a 1997 E320 then.

__________________
Paul S.

2001 E430, Bourdeaux Red, Oyster interior.
79,200 miles.

1973 280SE 4.5, 170,000 miles. 568 Signal Red, Black MB Tex. "The Red Baron".