Hi my key won't talk to my transponder aerial I can unlock the car turn ignition  on and when I go to start nothing except the red light between the speedo and the rev counter flashes very quickly 

Battery Ive fully charged I've removed  it to see if it would  reset the ecu  but it didn't 

Tried 6 auto lock smiths 4 didn't respond  2 did but never turned up spare  key came without  a chip  3 weeks without a car now 

6 hours ago, vespa278 said:

Hi my key won't talk to my transponder aerial I can unlock the car turn ignition  on and when I go to start nothing except the red light between the speedo and the rev counter flashes very quickly 

The central locking system is almost completely separate from the PATS (immobiliser) system. The fob buttons and the central locking receiver play no part in PATS, and it is the PATS light that is flashing. Google PATS flash codes. There is a code system that gives some clue as the the cause.

PATS is passive, it needs no battery in the key. A coil around the ignition barrel energises a PATS chip inside the key, extracts a code, and two of the car's electronic modules (ECU and IC or Instrument Cluster in the Focus, not 100% sure if the same in 2007 Fusion) communicate to verify the code and enable starting. A spare key with no remote buttons will still contain a PATS chip. So if the spare did once start the car, but no longer does, it is less likely to be a key problem, more likely to be a PATS transceiver or communication problem.

15 hours ago, vespa278 said:

spare  key came without  a chip

Hello Steve, firstly Tdci-Peter (above answer) has covered it. The locking / unlocking of the car has nothing to do with the immobiliser so no need to concern yourself about the battery in the keyfob.

I assume that you did at one time have at least one key that used to start your car - what happened to that key ?

The spare key you say came without a chip !! - so its as much use as a lump of coal, its not a spare key.

You need to read the PATS flashing code light to understand why it is not allowing the car to start. Have you changed any parts on the car recently for example, fuel pump, instrument cluster, ECU ?

 

On my brothers 2008 focus it was doing this and it was dodgy electrical connectors on the way to the ecu (and I agree with what has been said above)