Why Rover 75 ECU goes wrong?

zsomborovics · 28th February 2013, 18:19

Hy,

I'm new here, and sorry for my english (not my native).
We have a problem with our Rover 75 2.0 cdti. The ECU sometimes goes fully wrong. That will be the third times we will change it and we have to change it with the immobilizer (expensive) because it won't work without it, just with each other. We have no idea why is it? Do you have an idea what should we check? We used the car, and stopped the engine at the shop, and after that we couldn't start it. After we changed the immobilizer and ECU, the car was good so far (1-1,5 month) and now, the same.......

I think maybe the ecu got excess voltage... but how?? Any idea??
All of the fuse is fine.
Can a short circuit couse it?? But all of the consumer is working...
Please help me..

Thanks,
Zsomborovics

Lovel · 28th February 2013, 19:12

Quote:

Originally Posted by zsomborovics

Hy,

I'm new here, and sorry for my english (not my native).
We have a problem with our Rover 75 2.0 cdti. The ECU sometimes goes fully wrong. That will be the third times we will change it and we have to change it with the immobilizer (expensive) because it won't work without it, just with each other. We have no idea why is it? Do you have an idea what should we check? We used the car, and stopped the engine at the shop, and after that we couldn't start it. After we changed the immobilizer and ECU, the car was good so far (1-1,5 month) and now, the same.......

I think maybe the ecu got excess voltage... but how?? Any idea??
All of the fuse is fine.
Can a short circuit couse it?? But all of the consumer is working...
Please help me..

Thanks,
Zsomborovics

Hi there,

Was the DDE4 ECU changed due to water ingress?

Have you inspected the insides of the glow plug relay which is next to the DDE4 ECU? The insides of the glow plug relay can retain water and corrode, causing shorting of wires, and other issues.

What are the capacitors of the DDE4 reading with ignition switched on?
While cranking?
While engine running?

Example photo relay
http://www.the75andztclub.co.uk/foru...low+plug+relay

Regards.

Thomas · 28th February 2013, 19:47

Moved to technical help forum

crofts · 1st March 2013, 02:16

Quote:

Originally Posted by Lovel

Hi there,

Was the DDE4 ECU changed due to water ingress?

Have you inspected the insides of the glow plug relay which is next to the DDE4 ECU? The insides of the glow plug relay can retain water and corrode, causing shorting of wires, and other issues.

What are the capacitors of the DDE4 reading with ignition switched on?
While cranking?
While engine running?
Regards.

The most common problem is the plenum drains below the ECU and servo get blocked, water rises & floods ECU. Look for a 'HOW TO' or search PLENUMS.
Most times, fortunately, slow drying out of the ECU rectifies the problem.
Then look for 'SPY HOLE MOD' to make future cleaning of the drains easy.
Block the drivers side entrance to the plenum chamber (near bonnet hinge) with gauze or similar or buy the shield from 'jules' (about £10) find details in the 'spares for sale' sticky. Passenger side has plastic shield... easily seen.

There are 100's of warnings about the plenums flooding on the forum, it's mentioned almost daily http://www.the75andztclub.co.uk/foru...cons/icon4.gif

zsomborovics · 1st March 2013, 06:18

There is no water near the ECU. We know this problem about the flooding and sometimes we checked it in time.... The place near the ECU and glow plug relay is dry! We checked the immobilizer and it's dry.. No water... We sure the problem is not the flooding...

The plenums are ok!! We cleaned it before this incident.

I would like to ask, can the MAF sensor couse this problem? Because it's bad. In every gear around 1000 rpm the engine starts to uneven running... before and over this rpm it's ok... We unconnected the maf sensor 1-2 month ago and it was good. We changed this sensor, and the uneven running at 1000 started again 1 week later. And now the ECU wrong. Just an idea.

We connected a computer to the car. It shows us that the immobilizer can't communicate with the ECU!! That was the problem at the last same incident! Can't communicate but why.. At the last incident we had to buy a new used ecu and immobilizer. But it happened again.

David Lawrence · 1st March 2013, 07:18

Quote:

Originally Posted by zsomborovics

Hy,

I'm new here, and sorry for my english (not my native).
We have a problem with our Rover 75 2.0 cdti. The ECU sometimes goes fully wrong. That will be the third times we will change it and we have to change it with the immobilizer (expensive) because it won't work without it, just with each other. We have no idea why is it? Do you have an idea what should we check? We used the car, and stopped the engine at the shop, and after that we couldn't start it. After we changed the immobilizer and ECU, the car was good so far (1-1,5 month) and now, the same.......

I think maybe the ecu got excess voltage... but how?? Any idea??
All of the fuse is fine.
Can a short circuit couse it?? But all of the consumer is working...
Please help me..

Thanks,
Zsomborovics

Have you tried unplugging the fuel burning heater? I believe that has been known to cause communication problems.

zsomborovics · 1st March 2013, 09:27

Quote:

Originally Posted by David Lawrence

Have you tried unplugging the fuel burning heater? I believe that has been known to cause communication problems.

I have tried this now, and doesn't work. The fuel burning heater is the webasto box "thermoking" am i right? On the right side if i standing in front of the engine.

But i have unplugged just the first connector on the webasto with the about 4 wire but i think that was enough. There was another with 2 wire as i can remember correctly.

FrenchMike · 1st March 2013, 10:01

Quote:

Originally Posted by zsomborovics

We changed this sensor, and the uneven running at 1000 started again 1 week later. And now the ECU wrong. Just an idea.

Hi,

What kind of MAF sensor did you bought.Most of the cheep ones you see on Ebay are counterfeit and don't last long ...
Can you lead this measurement:

Mike

zsomborovics · 1st March 2013, 11:01

Quote:

Originally Posted by FrenchMike

Hi,

What kind of MAF sensor did you bought.Most of the cheep ones you see on Ebay are counterfeit and don't last long ...
Can you lead this measurement:

Mike

The sensor is from the ebay...... I will change it later... Can cause a bad sensor go bad the ECU?? What if i use the car unplugged sensor long?

The computer what is connected to the car shows the ecu and the immobilizer can't communicate. How can i detect the problem is in the immobilizer on in the ecu? The problem we can't use a new ECU without its immoblizer.

FrenchMike · 1st March 2013, 13:02

Quote:

Originally Posted by zsomborovics

it later... Can cause a bad sensor go bad the ECU?? What if i use the car unplugged sensor long?

The computer what is connected to the car shows the ecu and the immobilizer can't communicate. How can i detect the problem is in the immobilizer on in the ecu? The problem we can't use a new ECU without its immoblizer.

No damage to the ECU and you can run safely with MAF disconnected.

It's not a good idea changing the ECU,better is have it repaired as possible.

There are some ECU experts here,sure someone is able to give you an answer !

Mike

28th February 2013, 18:19	#1
zsomborovics Newbie Rover 75 Join Date: Feb 2013 Location: Szentes Posts: 14 Thanks: 0 Thanked 0 Times in 0 Posts	Why Rover 75 ECU goes wrong? Hy, I'm new here, and sorry for my english (not my native). We have a problem with our Rover 75 2.0 cdti. The ECU sometimes goes fully wrong. That will be the third times we will change it and we have to change it with the immobilizer (expensive) because it won't work without it, just with each other. We have no idea why is it? Do you have an idea what should we check? We used the car, and stopped the engine at the shop, and after that we couldn't start it. After we changed the immobilizer and ECU, the car was good so far (1-1,5 month) and now, the same....... I think maybe the ecu got excess voltage... but how?? Any idea?? All of the fuse is fine. Can a short circuit couse it?? But all of the consumer is working... Please help me.. Thanks, Zsomborovics

28th February 2013, 19:47	#3
Thomas This is my second home MG6 1.8T GT SE Join Date: Mar 2009 Location: Falkirk Posts: 9,510 Thanks: 106 Thanked 173 Times in 128 Posts	Moved to technical help forum __________________ MG6 1.8 TCi in Artic White 1975 Land Rover Series 3

1st March 2013, 06:18	#5
zsomborovics Newbie Rover 75 Join Date: Feb 2013 Location: Szentes Posts: 14 Thanks: 0 Thanked 0 Times in 0 Posts	There is no water near the ECU. We know this problem about the flooding and sometimes we checked it in time.... The place near the ECU and glow plug relay is dry! We checked the immobilizer and it's dry.. No water... We sure the problem is not the flooding... The plenums are ok!! We cleaned it before this incident. I would like to ask, can the MAF sensor couse this problem? Because it's bad. In every gear around 1000 rpm the engine starts to uneven running... before and over this rpm it's ok... We unconnected the maf sensor 1-2 month ago and it was good. We changed this sensor, and the uneven running at 1000 started again 1 week later. And now the ECU wrong. Just an idea. We connected a computer to the car. It shows us that the immobilizer can't communicate with the ECU!! That was the problem at the last same incident! Can't communicate but why.. At the last incident we had to buy a new used ecu and immobilizer. But it happened again.