Could my S350 have blown the ISM and ECM at the same time?
08-23-2012, 04:51 AM
#1
Newbie
Thread Starter
Join Date: Aug 2012
Posts: 2
Likes: 0
Received 0 Likes
on
0 Posts
S350 W221
Could my S350 have blown the ISM and ECM at the same time?
This is my first post on this forum for the first merc I have owned. I bought a pre-owned merc s350 (w221) last month with ~72000 kms on it and car was running just fine for the first 10 days.
I decided to send it in for a diagnostic check to make sure everything was in order and the authorized merc workshop told me that there were no error codes and I should collect the car. Just as I was driving out of the garage the car stopped never to come on again! Nothing was coming on.
It took the workshop 2 days to tell me that the problem was with the ISM which needs to be replaced (~$900). I had to wait 5 weeks for the part and after installing it yesterday they are telling me that the car still won’t start.
Now they are telling me that the ECM is blown and that it seems to be tampered by the previous owner. Why did it take them 5 weeks to tell me this? Would they not check this in the first place?
They want me to order a new ECM (~$3500) but I am not sure these guys know what they are doing. Was there any problem with the ISM in the first place?
I do not know anything technical about cars but understand that these parts have to be factory ordered as they are linked to the particular chassis. I seem to have no choice but to listen to these guys.
But I feel I am being ripped off. The workshop is also not taking any responsibility for the repairs even though the car went in in working condition. Can someone please help me ask the right questions off the workshop and what options do I have?
Really appreciate any help I can get on this forum.
PS – imported parts can cost more in India because of import duties
I decided to send it in for a diagnostic check to make sure everything was in order and the authorized merc workshop told me that there were no error codes and I should collect the car. Just as I was driving out of the garage the car stopped never to come on again! Nothing was coming on.
It took the workshop 2 days to tell me that the problem was with the ISM which needs to be replaced (~$900). I had to wait 5 weeks for the part and after installing it yesterday they are telling me that the car still won’t start.
Now they are telling me that the ECM is blown and that it seems to be tampered by the previous owner. Why did it take them 5 weeks to tell me this? Would they not check this in the first place?
They want me to order a new ECM (~$3500) but I am not sure these guys know what they are doing. Was there any problem with the ISM in the first place?
I do not know anything technical about cars but understand that these parts have to be factory ordered as they are linked to the particular chassis. I seem to have no choice but to listen to these guys.
But I feel I am being ripped off. The workshop is also not taking any responsibility for the repairs even though the car went in in working condition. Can someone please help me ask the right questions off the workshop and what options do I have?
Really appreciate any help I can get on this forum.
PS – imported parts can cost more in India because of import duties
08-23-2012, 11:46 AM
#2
Super Member
I find it hard to believe that two units (that otherwise do not cause many issues) ,are defective all of a sudden,
after a diagnostic-visit to the shop.
My 2 cents is; they must have done something to cause an issue ,but might as well be something completely different ,then the above mentioned units.
The only way to tell is with Star(Xentry) and a Technician with indeep W221 Expertise, mostly to be found at the larger dealerships that do a lot of W221's..
Unless you have a renown person at an independent shop that knows what he or she is doing.
You have got a complex rolling computer called W221, that needs to be treated accordingly.
Try to get the car rolling out of there or take your loss and sue later and find a larger MB-dealership etc. or a renown expert...
after a diagnostic-visit to the shop.
My 2 cents is; they must have done something to cause an issue ,but might as well be something completely different ,then the above mentioned units.
The only way to tell is with Star(Xentry) and a Technician with indeep W221 Expertise, mostly to be found at the larger dealerships that do a lot of W221's..
Unless you have a renown person at an independent shop that knows what he or she is doing.
You have got a complex rolling computer called W221, that needs to be treated accordingly.
Try to get the car rolling out of there or take your loss and sue later and find a larger MB-dealership etc. or a renown expert...
Last edited by marthyh; 08-23-2012 at 12:00 PM.
08-23-2012, 12:22 PM
#3
Super Member
Yikes. I'm assuming there wasn't any limited warranty associated with the sale? Pretty risky car to buy used in such a harsh market. Regardless, I hope you find a reasonably inexpensive solution to your problem! Good luck!
08-26-2012, 12:01 AM
#4
Newbie
Thread Starter
Join Date: Aug 2012
Posts: 2
Likes: 0
Received 0 Likes
on
0 Posts
S350 W221
Folks - I finally got the repaired vehicle yesterday. The merc workshop gave back the ISM and ECM they replaced in the car and it seems to be working fine. But I am going to take a few more test drives before I am totally satisfied.
Below is an explanation from the mechanic - don't know what to make of it. Can the experts on this forum verfiy if the procedure followed was what was required?
"Initially when the vehicle stopped working, engine was not cranking and vehicle was not coming to neutral.We did free wheel using special tool and brought the vehicle inside the workshop.We did short test which is normally the procedure, in which ISM was not showing meaning internal failure in ISM. ECU (Engine Control Unit) and ETC (Electronic Transmission Control unit) were showing but not communicating. Further checking confirmed ISM (Intelligent Servo Module) faulty as CAN (Control Area Network) voltage was zero. After customer approval ISM was replaced. After replacing ISM all the three modules (ISM.ECU.ETC) started communicating but engine was still not cranking.With diagnostic steps we checked all circuits in EZS (Electronic ignition Switch) where drive authorization from ISM,ETC was ok but failed from ECU. We checked drive authorization in ECU and found no value appearing in star diagnostic screen. It means drive authorization failed from ECU.While checking ECU wiring and ECU , we came to know that the same is tampered and needs replacement. This was the stage where we approach ECU checking and the reason for not getting the tampered indication in the beginning.”
Thanks!
Below is an explanation from the mechanic - don't know what to make of it. Can the experts on this forum verfiy if the procedure followed was what was required?
"Initially when the vehicle stopped working, engine was not cranking and vehicle was not coming to neutral.We did free wheel using special tool and brought the vehicle inside the workshop.We did short test which is normally the procedure, in which ISM was not showing meaning internal failure in ISM. ECU (Engine Control Unit) and ETC (Electronic Transmission Control unit) were showing but not communicating. Further checking confirmed ISM (Intelligent Servo Module) faulty as CAN (Control Area Network) voltage was zero. After customer approval ISM was replaced. After replacing ISM all the three modules (ISM.ECU.ETC) started communicating but engine was still not cranking.With diagnostic steps we checked all circuits in EZS (Electronic ignition Switch) where drive authorization from ISM,ETC was ok but failed from ECU. We checked drive authorization in ECU and found no value appearing in star diagnostic screen. It means drive authorization failed from ECU.While checking ECU wiring and ECU , we came to know that the same is tampered and needs replacement. This was the stage where we approach ECU checking and the reason for not getting the tampered indication in the beginning.”
Thanks!
