Technical Imobiliser 1.9TD 2000

[nemander]

My dear mh (1.9 TD 2000) refuses to start and the "code" key is on. It has started recently couple of times, but typically doesn't. I have checked and sprayed all the connections and bought new ignition lock but it did not help. The ecu 46417024 looks ok and the antenna resistanse is 32 ohms which I assume to indicate it is ok. Is there any "easy" way to test the ecu? What else could I do before removing the imobiliser - given that I can find someone who really knows how to do that.

 

[nemander]

I did check the earth cable from battery to engine and it looked fine, but is there some other earth cable somewhere?

 

[Communicator]

Hi nemander,
Welcome to the forum.
I can sympathise with your plight. Unlikely to be the cause, as it would create other problems, but have you checked the main chassis earth point below the front end of the battery? (You only mention engine block earth.)
I seem to have cured an emerging problem on my 2006 x244, by cleaning the contacts at the code receiver mounted on the steering column. As you have checked the aerial, I presume that you have done this.
I have seen a report of an opencircuit aerial connection, but this would give a complete failure.

Have you checked for any connections close to the pump, as there are 3 wires to connect. Ignition on, signal, and earth.

Unfortunately the design life of the electronics is typically 20 years. If you are considering removing the immobiliser from the injection pump, than there are several threads on forum relating to immobiliser removal from mechanical injection engines. Here is a link to one such thread.

If your vehicle is an "A" class then access may be restricted.

 

[nemander]

Big thanks for your answer. Previously I just visually checked the earth cables, but now I took them off, cleaned all surfaces and connected back - no impact. And froze to death as it is +2 here atm
The consistent behaviour seems to be now that on first try the key code warning is there, second try it is not, but it doesn't start and on third and on any additional attempts the warning light is always on. If I try again after some hours it behaves exatly the same way.
Any experience on changing the control box only? There seem to be some old ones available and also new boxes but the price is 200€+ so would not like to buy one just to find out it doesn't help. I assume it would need to be at least reprogrammed somehow to work with my keys - I do have the red key if that helps.

 

[nemander]

... and yes, have checked the control box connections and took it inside to warm it up - in case that would help. Disconnected the wires to the pump and sprayed the connectors. Nothing seems to help. Any advice how to check if the signal gets to the pump?