Hi

First time I’ve posted on a forum so go easy on me. 
I have a fiesta 1.6 diesel zetec s on a 56 plate which I’ve changed the battery on but the car will not even turn over now. When I switch on the ignition all the lights you would expect to see come on but turning the key to the start position and nothing happens. I’ve been advices that it’s the immobiliser but how do you reset it. I’ve checked the whole starting circuit from the key switch to the start relay function and the only thing missing its the negative return for the start relay which should I believe come from the engine management system. I’ve changed yge battery in the ignition key just in case but still nothing. This there a way to reset the immobiliser?

I'm assuming the new battery has been checked? Lol.

Would've thought the immobiliser light would flash if that's the issue.

Turn out to be the alternator not charging so the old battery has been reinstalled having been recharged to 12-13 volts. Alternator still needs to be changed but not going to do that until I’ve got it running again. I’ve linked through the start relay and I get the engine turning over so happy the start issue is not the battery or alternator.

The red immobiliser light on the dashboard is solid for about 30 second after turning on the ignition then flashing the code 23 . I understand that’s an immobiliser issue.

Just for your information the 'battery' in the key has nothing to do with the immobiliser. You could take the battery out the key and the immobiliser would still work. On the other hand the remote lock/unlock with the buttons would be a total fail.

Ok thanks for the info. I’m at the point of trying anything that would get the car to start again. I’ve tried everything I can think of twice.

Remove the negative battery lead from the car body. Clean the metalwork up and make sure the lead is nice and clean both ends. Apply a small amount of Vaseline to the connectors and make sure they are tight at both ends when you put it back.

Thanks the battery is fine it’s definitely something to do with the immobiliser. As mentioned I’ve checked and have the correct voltages at the correct locations for the car to start the only thing missing is the return from the immobiliser on the start relay coil. When you turn the key you get the 12 volts to the start relay coil from the key switch. The return I understand is from the immobiliser and is controlled by software. This I believe is the way the immobiliser stops the car from starting by interrupting the start circuit.

Have you seen this "s#it" video ? same car and probably the same fault.

 

Hi

thanks for the reply. Yes I’ve seen the video you mention and agree with your comments. It would appear to be the same fault meaning a reprogram is required. I’ve  been told that it’s quite a common problem on the 1.6 diesel that when the battery is disconnected/jumped it can take out the immobiliser. It’s strange that I can’t find any other videos or comments from people having had the issue. Maybe I’m looking in the wrong place. 

Hi my car sat for a week over the holiday and the same thing has happened to me. Did you have any luck sorting this? My mechanic said he won’t touch it and I should go to a Ford specialist 

Full marks to your mechanic for at least understanding the problem.

It's a Ford main dealer reprogramme event only. There are potentially 5 or 6 specialist auto-electricians in the country who could do the job, but I'm not sure how you would find them.

So, going by the video, it’s the OSCA interface that looks like the magic thing that you use to allow support (the big fat controller in the sky?) to remotely “realign the PATS”.  That’s scary! So I could potentially be subject to this craziness with my old MK6 too.  I wonder how many grinder wielding mobile guys have got access to an OSCA or the like.