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Not Starting - Possible Immobiliser Problem?

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#1 MrsD



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  • Name: Claire
  • Ford Model: MONDEO
  • Year: 2003
  • Location: Lincolnshire

Posted 02 March 2013 - 11:30 AM

Hi there I'm hoping someone can help me out.

I've got a mk3 mondeo on 52 plate and it won't start.

When I turn the key it turns over but won't fire up, the dash lights up when the key is put in and the LED flashes but when I turn it all the displays go off and the led doesn't flash, My hubby suspects it's immobilised itself and was wondering if there is anyway to over ride the immobiliser?

Any advice would be most appreciated

Thanks :unsure:

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#2 Stoney871


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  • Name: Clive
  • Ford Model: 2015 Focus ST3 250BHP
  • Year: 2015
  • Location: Devon

Posted 02 March 2013 - 12:14 PM

When the LED flashes you may see a pattern.

Watch it next time and you may be able to work out what code it's flashing

The code is usually repeated about 10 times and will signify a two number code i.e.-

Flash flash pause flash would be code 2,1.

These codes assist in diagnosing immobiliser faults.

If the light flashes rapidly with a long amount of flashes it usually means the key is not recognised at all.


From Fordwiki-


PATS Immobiliser Fault Codes




If a fault develops on a vehicle fitted with Ford PATS there are a series of simple checks which can be carried out before proceeding, if necessary, to the FDS2000 diagnostic programme. There are also a number of self-diagnostic two-digit codes which may be displayed by the indicator LED which indicate a specific fault and could avoid the need to proceed with the FDS2000 diagnostic programme.

Note: The indicator LED must be carefully observed and the sequence of flashes noted.

When the two-digit codes are flashed, for example 1:3, a single flash followed by a break, followed by three flashes and a break, will be repeated ten times before the LED finally goes out.

Fault Finding Procedure-


Fault - Engine does not start or crank: LED does not illuminate

PATS system fuses in foot well fuse box. Fit or renew as necessary.


If alarm is fitted check whether LED functions for alarm: If OK go to FDS2000. If not OK check cigar lighter fuse (this also supplies power to


Fault - Engine does not start or crank: LED flashes rapidly. (Engine is immobilised but key will not cancel immobilisation)

Check: Leave ignition switched on for at least one minute or until LED starts to flash two-digit code. Note the code being flashed and compare with the following list:-

Code Problem Check


1 : 3 Key code not received is the key obscured, try again with different key, key may be damaged/faulty

1 : 4 Partial code only received is the key obscured, try again with different key, key may be damaged or faulty

1: 5 Key not programmed to PATS Programme key

1 : 6 Faulty link between PATS and EEC v module check with FDS2000


Programme key.

Fault: Engine does not start or crank: LED illuminates for 4 seconds and goes out: (PATS is working correctly, possible fault elsewhere in system)


Starter solenoid relay, renew if necessary. If still no start, Go to FDS2000.

Fault: Engine cranks but does not start. LED illuminates for 4 seconds and goes out (PATS is working correctly, fault elsewhere in system)


Power to PCM or fuel pump (diesel), if still no start, Go to FDS2000 Check PCM fault, Go to FDS2000 (Petrol and Gas engines)


Fault: Engine starts but LED stays on


Leave ignition on (engine running) for at least one minute or until LED starts to flash two-digit code 2 : 1 Less than three keys programmed into module: vehicle can be driven but one or two more keys should be programmed into memory.

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