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sean, Ford Technician
Category: Ford
Satisfied Customers: 3105
Experience:  Ford Master Technician.
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fordmondeo 2006 immoboliser problem

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fordmondeo 2006 immoboliser problem

Hello, I hope the following assists you.

As the speedometer is showing dashes then there is a communication issue with the engine management control module (PCM), the immobiliser system is integral to this module which is why the vehicle remains immobilised. When the PCM won't communicate no diagnostic tester will be able to access the system.

You need to check the power and earth supplies to the PCM, the PCM is located just behind the driver's side front suspension strut top, you can see the connector if you look in this area in the engine bay it will have a metal security shield over it.

Before accessing the PCM check that the PCM relay operates, the relay is located in the engine bay fuse box, it is the left hand small relay of the 2 small relays in the middle of the fuse box. With the ignition on pins 2 and 5 should be a 12 volt feed, pin 1 is earthed by the PCM to operate the relay.

Check fuses 9, 33, 40, 41 and 42 in the fuse box under the bonnet plus fuse 67 in the fuse box inside the car as all these fuses supply the PCM and associated systems.

Check the main earth points in the engine bay, the earths under the battery and on the driver's inner wing near the PCM connector. You can try disconnecting the instrument cluster as there are problems where the cluster can shut the PCM down so disconnect this and see if the PATS light operates correctly.

It is a little unusual that the immobiliser light flashes fast when the PCM is not communicating, normally it continues to flash at the same rate as it does when the ignition is off.

Start with these points and let me know if I can advise further, I'll reply as soon as I'm able to.

Best wishes,


Customer: replied 3 years ago.

sean tried everthing you suggested no luck immoboliser light stillflashing rapidly andgrey relay switch ticking rapidly wont start the problem started when I parked my caravan up unhitched the tow bar drove forward and forgot to take safety wire bond off which stopped me with a jolt switched off took wire bond off would not start since could you please send email to *****@******.*** regards barry

Hello again,

it's a possibility that the PCM has been damaged, if all the power and earth are OK at the PCM then this would indicate a PCM fault.

Let me know if I can assist further.

Best regards,


sean and other Ford Specialists are ready to help you
Customer: replied 3 years ago.

Customer: replied 3 years ago.

my ecu is inside the cardrivers side how do I get it out and if I get second hand ecu with the same number key and transponder should it go regards barry

Hello again,
to remove the ECU unbolt the connector from in the engine bay then inside the car remove the GEM from the ECU and the retaining nut and the ECU pulls down into the car.
If you get a key that is already programmed to the used ECU then it won't need programming again. The quickest thing to do is swap the remote fobs over as the PATS transponder is in the fob.
Customer: replied 3 years ago.

hello sean got another ecu same number key and transponder still the immoboliser light flashing ten to the dozen when ignition switched on should I have new ecu as still wont start regards barry