Non starter, can’t connect to ecu mk1 TD4 2006

I’ve never used a scanner on this car before, only bought 6 months ago. But I’ve run my scanner on other cars and had RAC check at the weekend and they also couldn’t get signal.
The temp gauge, fuel pump both happening at exactly same time makes it feel connected, although I will check if any live feed at pump.
Also, given max temp on gauge, the fans are not running which I would have expected if sensor faulty

Ok, check the 12v feed to the pump just to eliminate that.
Out of interest, have you jump started another car off yours recently?
Mike

Without seeming rude haven't you got breakdown cover ?
Seems it could be this or that, personally I pay my £50 a year and let them tell me whats wrong.
If no home start get a pal to tow you a mile away then phone em.

Yes, chaps from the RAC have already been. They tried many of the things suggested here in this post including (unsuccessfully) hooking up to their computer, in the end the only solution they could offer was to tow to a repair garage.

I'm thinking this is possibly a data bus fault. That would explain the high temp warning on the dash and lack of connection with the OBD2 port. Bus faults can be buggers to trace. Ideally you need to scope the CAN wires to see if any fata is being sent.

Hi and thanks.... so this is getting technically above my pay grade now.
Are we saying this could be a problem with the wiring of the car, or something wrong in the ECU unit itself?
I know you can't say for sure, but if I could pin it down to the ECU unit, then i would buy from eBay a used ECU, Imob unit and key chip...... and hopefully be done with it.
???

On the whole the ECUs are very reliable. In my experience, the wiring or connections fail before the ECUs themselves.
The problem with buying replacement ECUs, is you don't know which one is faulty, if any. You need to check all the plugs on all the ECUs first. The ECUs communicate with each other over the CAN bus or K line bus, depending on the individual ECU. So you need to check the connections at the engine ECU, the ABS ECU, the Ipack ECU and the TCM if it's got an automatic gearbox. Then if all connections look sound, you need to check the CAN bus wiring (thin Yellow/Brown and Yellow/Black) for chaffing and damage.

There was a post on here earlier in the month that mentioned CAN bus damage behind the stereo.

With a fault like this you have to try and stop looking for the complicated answer. Like Nodge says it's probably something simple like a damaged cable or a dodgy connection but as always finding the fault is easier said than done.
I'm a computer engineer and I used to work on a contract where the computers were linked by coaxial cable. On a daily basis I attended calls where the fault description provided by first line diagnostics was always, suspect faulty network card. In 100% of the calls over several years the fault was always cabling but it was easier for them to point the finger at the network cards because we were responsible for them.
I suspect when you find the fault it'll be something stupid and you'll kick yourself for not finding it sooner.
Good luck with it and let us know how it goes.

Hi,
Just to update. Have taken out radio and checked behind, nothing looks chaffed or broken. Have put back the original radio just rule that out anyway.
One thing I have just noticed is that the engine check light does not come on at all. Also, when put in reverse, no reversing lights come on, guess that might be a red herring but worth mentioning anyway.
Fact that engine check light does not come on, and on top of the other issues, leads me to think that engine management eco might actually be dead.
Any body go any thoughts, agree/disagree?
Thanks

Is it a manual or auto?

Manual

The power for the reverse lights is fed from fuse 2 in the internal fuse box. Fuse 2 is powered from the ignition switch terminal 2A on the Brown/White wire.

The ECU is fed with power from several fuses in the engine bay fuse box.