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M119 ETA rewire, ASR light on

36K views 44 replies 16 participants last post by  bioinsul_nightmare 
#1 ·
So, I was finally bitten by the ETA wiring bug.

Symptoms were;

- During normal driving, ASR light illuminates and car switches to limp-home mode
- Shorting pins 1 and 6 on the 38pin socket does not turn off limp-home
- No CEL or codes for the first few miles
- Eventually get, code 6 on the DM for 'high idle'
- Engine idles fine

So I studied the fine work of Pete from the V12 Uber Alles, Repair Help for Mercedes Benz S600 V12 W140 site and prepared for the worst. Instead of cutting into the harness for the ETA, I just removed it and opened the non-control side of the case. There I found lots of rotten wiring, but, as noted by Pete, none to the control side of the unit. In fact, my wiring to the control side was a ribbon cable. And, my PC board was vertical instead of horizontal in the ETA.

So I spent my Saturday rewiring, which was tedious and painful because I had to make my own diagram of the PCB. It was different from what Pete had documented and the connection numbers were obscured by someone who seemed to think that more is better, even when soldering! :(

Several hours and about 55 feet of the wire recommended and I was able to get things back under control. See the pics below for more fun.

Some notes;

- You will need a security bit set to remove the screws of the ETA cover
- It's a good time to replace the ETA gaskets (intake manifold to ETA and ETA to MAF)
- It's a good time to replace the PCV tubing that connects to the back of the ETA

I reinstalled the ETA today and performed the relearn procedure and WOW! What a nice smooth power curve I have now. :)

Thanks to Pete, Brett, Jonathan, Robert and Dietrich for all their posted brain power and advice.
 

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#27 ·
I should had found this thread before I started to rewire 2 years ago.
I made a mistake reversing motor(+) and (-) just checking the resistance using an ohm meter which could not read the small resistance. This caused no engine starting and it took me an extra time to complete the job. Using a good multimeter, I noticed that there existed some small resistance and I understood the reason why the engine didn't start. Reversing the line to the connector pin#4 and 11, everything became OK.

There is no limp home mode anymore and the car is running fine.
 

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#6 ·
The entire cable was degraded, just as the wires in the picture. I will see if I can find the pics I took of it. You can see at the connector that the cable is in very poor condition.

Thanks for the encouragment, unfortunately this will only lead to a false sense of ability, which will then have me thinking I can fix anything! ;)
 
#5 ·
Just replaced my with a reman for $400 plus $150 refundable core - the guy on eBay out of Florida.

I am very well pleased with the unit - new cable and connector, new gaskets both side and tun - turned out well. When purchased on eBay, supposedly "owner lifetime warranty" versus 1yr warranty when purchased on his website..

Just wish someone here in the US had the cable available, but wishes don't make it so..

Good work - saved yourself a chunk !
 
#8 · (Edited)
Nice work and pics.

Did you splice into the existing wires coming from the ECU connector where it was no longer degraded? Or, did you dismantle the ECU connector and replace the wire connector to connector?

Brett
Thanks Brett.

I completely removed the old wire, disassembling the connector and desoldering all 11 pins. Then resoldered all the pins. So the wire from the pins to the PCB is all new.

EDIT: The harness was degraded its entire length. I did follow the previous advice given and left the 10" of sheathing at the ETA intact, just pulled new wires through it after removing the old, and bits of insulation.
 
#10 ·
Yes, the harness from the fender connector for the ETA to the computer seems to be newer and not degraded. I have attached two more pics, one of the connector and wirebundle prior to rewire and on one of the finished connector. Yes, the yellow wire was a bit long, but it still managed to snuggle in there.
 

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#13 ·
Thanks for your kind words!

Yes, I've been Benzless since the summer of 2006. It was a sad day when I sold my baby. It just got to the point where it wasn't fun anymore. It demanded too much of my time and money. But I'm glad I bought it, no regrets at all. It was a great car.
 
#15 ·
Thanks CRBenz!

I think if you never soldered (welded?) before, this job is going to be tough and perhaps not recommended. There is an art to removing the old solder and resoldering new wires without damaging the PCB. Also, there are 11 conductors, so you have to be very careful not to cross connect any circuits. The 14Ga wire carries a decent current, so accidentally connecting it a pin which needs milliamps to operate would likely cause some other component to fail.

I used a magnifying lamp to do the work and even then it was an all day job.

For me it came down to risk/reward. I knew if I could not fix it, it was going to cost me $400-$600 for a rebuilt unit or $900 for a new one. The total cost of parts was $40.
 
#17 ·
I want to share my experience for the same ETA problem.

The first photo, difference between the cable in cooking around the engine, and the other and connected to the engine management computer.


Here is the throttle body disasambled, bad condition!


Same thing with the orange cable, cracked and ugly.


Here is my fix on the cable, just cut it around the better end, because i cannot dissasemble the connector, or get a new one, do you know how ??


Here is the first tryout, a little bit sloppy work for my behalf.




And this, the throttle potition sensor, it had just a little bit of an accident, and is impossible to repair due to strange materials used, i contacted the manufacturer and they seem to have really strict contract regarding this unit. If anyone can point me out where i can buy this plug, and the resistor plate, i would be greatful.
 
#19 ·
i am currently rewiring my eta unit. if possible, can someone upload an image of the board with its respective whire color labeled on it? I am stuck on which wire goes to which part of the board. my wires were soo bad, they were pretty much bare wire. I would appreciate any help.
 
#20 ·
I have had a couple of questions regarding the chart I posted, so perhaps this illustration might clear up the confusion. The view below is what you see when you remove the cover of the ETA -- the solder side of the pcb. I wouldn't put too much stock in the wire colors as they seem to vary, even in the same model year. The important part is matching these connections to the connections on the fender plug.
 

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#21 ·
Thank you for putting up the diagram. I just finished wiring my eta board and still have the issue....even worse, the ASR light comes on instead of just the warning triangle. I see what i did wrong on some of the wires. Hopefully it is not too late to fix.
 
#22 · (Edited)
Well, this is two years later but since I am rewiring the ETA on my car and found this thread useful, I thought I might point out a typo in the diagram of the circuit board. I think he meant to number it 3,2,1, 5,4, 9,8,7,6 instead of 3,2,1, 4,5, 6,7,8,9. Read from right to left, top to bottom... which may be why the last guy was still having problems with his ETA. So follows I redid the diagram and put instead the actual pin numbers so that there should be no confusion whatsoever.

Also,

Pin assignments:

4, 11 - Motor
12, 13 - Clutch
8, 10 - Switch 1, 10 is common
6, 10 - Switch 2, 10 is common
1, 3, 14 - Main Potentiometer, 1 is common
2, 3, 14 - Cruise Potentiometer, 2 is common

I like his write-up though, it was very useful.
 

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#40 ·
https://www.benzworld.org/forums/attachment.php?attachmentid=2444061&thumb=1

My ETA board configuration (1995 S420 with ASR) is-looking into the tip of wire or solder side, top row 11, 10, 7, middle row 5, 8, bottom row is 4, 2, 1, 8. Unfortunately, my wires have been corroded to such a bad level that some of the wires actually were broken so I couldn't figure out which numbers on the PCB corresponds to which pins on the connector. Please help!!!
 

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#23 ·
And today mine my ETA is finished, so this diagram is confirmed.

You will also need to clear DTCs on Pin 7 of the 38 pin connector for EA / CC / ISC. They remain in memory even if battery is disconnected. And the system will remain in limp mode even with the the rewiring done correctly unless these are cleared.

And again, thank you to the person who orginally made this write up, I just wanted to clarify the diagram because I found it unclear and thought maybe others may also.

A side note: I do love Mercedes and have owned many and will continue to only drive Mercedes, but... I had to rewire this along with the engine harness on my 95 S500 and after seeing how all the insulation on these wires turns to powder. I feel Mercedes should have been held responsible or should have taken responsibility for this. This sort of thing is unacceptable on a vehicle that cost about 100,000 new.

I have owned cars older than this and have not seen the wiring harnesses do that.
 
#24 ·
Awesome job on correcting my drawing, indeed you are correct about the transposed pin assignments.

As for the wiring harness, that's what happens when you let marketing run engineering. The harness is supposed to 'biodegrade', unfortunately it was a wee bit too successful at doing so.

Nice work getting yours back running well! :thumbsup:
 
#32 ·
I worry about the damaged ECU caused by the bad wires. But before to think so, I would check the stand alone bench test like this below.


I actually did it and confirmed that the ETA was properly rewired. But I noticed later that the wires to the motor were crossed. After fixing it, everything became OK.
 
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