W210 E320 ECU fried

[nellouk]

I have a 1996 W210 E320 with the 104 inline 6 engine and 055 chassis
I had a problem that was traced to the ignition switch electrics which were replaced but now the main ECU is faulty and cannot be seen with the diagnostic port and test equipment. The ECU also cannot be re-coded at all I'm told by the autologic boys and the local mercedes garage.
Does any techie know how I can fix this fault without spending the earth as I'm trying to sell the car. If its going to cost hunderds of pounds like it seems them I'm going to just break the car as its worth about 2 grand tops.
There was a suggestion that a W124 ECU can be used as it doesnt care about the imobiliser etc. Is this true and what part number could I use.
The W210 unit is a VDO part

 

[Autofix]

Hi,

It is possible that the 124 ECU could work but it will not be plug and play.

You have mentioned 2 faults, ign switch electrics and ECU. Are they both related to one symptom? What exactly is the fault/symptom?

I assume you have the "flick knife" type key? if so, you can fit the ECU and immobiliser ECU from another car and use the transponder chip from the donor cars key too.

 

[nellouk]

thanks for the reply

it is the flick knife key type

the initial problem was that the ign switch electrics were intermittent. an auto electrician repaired this and the car started ok only to fail after 4 or 5 starts. that was when we diagnosed the ECU was kaput.

another techie also suggested that we change the key, the imobiliser and the ECU from another W210.

or

we use a W124 ECU as they supposidly dont care about imobilisers and dont need re-coding, you are the second authority to say that they still need re-coding.

Do you have any idea how much an ECU and coding would cost?
I truly am thinking about breaking the car as the interior and the engine are perfect and I can recover a bit of cash that way.

thanks again

Nello

 

[Autofix]

the initial problem was that the ign switch electrics were intermittent. an auto electrician repaired this and the car started ok only to fail after 4 or 5 starts. that was when we diagnosed the ECU was kaput.

Most symptoms have just one cause. If the cause of your fault was not diagnosed correctly the first time then there is no logical reason to assume it was the second time. Maybe a second opinion is called for.

you are the second authority to say that they still need re-coding.

Sorry, I was not clear enough. When I said it wold not be plug and play what I meant was that it is wired differently. It would take a bit of looking to figure exactly what would need to be changed. The easiest option would be to go for a used set from another car, if it actually needs an ECU that is.

In a case like this you cannot safely condem the ECU unless its power supplies, grounds and communication line have been proven good first (properly, as in load tested not just with a test lamp). Do you know if that has been done?

 

[nellouk]

The initial fault was diagnosed to a defective ignition switch. That was replaced.

The feeds and loading plus wiring to the ECU are perfect.

what the auto-electrician and myself are trying to ascertain is the next course of action and also if its feasable cost wise.

we are certain the ECU is goosed.

Nello

 

[luders79]

Hello

When you say the car doesn't start do you mean it doesn't crank? Or cranks over but doesn't catch?

Lee

 

[nellouk]

it turns but is imobilised as the green and red leds show, the ECU will not connect to the diagnostic equipment thats how w e know its dead

 

[Cosworth]

Can't you find another E320 breaker

Take out 4 things that are coded.

1) ECU
2) Key fob
3) steering lock
4) Alarm unit

This should do the trick.

 

[Bolide]

AFAIK all W210s have an all-electronic gearbox and the gearbox ECU talks to the engine ECU. It's all CanBUS

The W124 has a hydraulic box and no box ECU. It doesn't have CanBUS

Based on that I'd sat using a W124 ECU will be more difficult than replacing W210 parts with W210 parts

Nick Froome
www.w124.co.uk

 

[bigasotonuk]

Hi,
That age and key type indicates to me the alarm system is a Scorpion and is an add on from the importer and it does not have a coded ignition switch/key the immobilisation point is at the alarm control box.
Try new fob batteries first as even if they lock/unlock the central locking it may not be sending the signal for the immobiliser. The fob sends two signals one for each function alarm and locking.
Have you got red/green leds in the drivers side door as well as the rear view mirror? If any of these don,t illuminate this could be a cause.
Try these remedies first before attempting bypassing immobiliser

 

[luders79]

Hello,

Something worth checking!! I believe that you might have a k40 relay on your car. It is in the front of the module box! Take this apart and check for a dry joint as i think that the wire for the alarm is on one of the circuits on that k40 relay! So if a dry joint then no power coming out of the relay so the imobilliser will be stuck on as the alarm unit doesn't have any power! Someone please correct me if i'm wrong!! I've had this happen on a early 210 diesel!

 

[television]

In other cars its a K39 but this is a starter lockout relay.


Has anyone checked to see if there is 12 volts on the ECU

If the crankshaft sensor is U/S it will crank but not start,, and the codes do not show this 9 times out of 10

 

[bigasotonuk]

Hi,
This appears to be an alarm immobiliser fault and would only require two cables going to the alarm control unit to be shorted out and the vehicle will start, note when hes says red&green led's are flashing=flat fob batteries/faulty immobiliser.

 

[television]

Hi,
This appears to be an alarm immobiliser fault and would only require two cables going to the alarm control unit to be shorted out and the vehicle will start, note when hes says red&green led's are flashing=faulty immobiliser.

You are correct and I forgot that bit