Immobiliser flashing fault codes

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Immobiliser flashing fault codes

Postby wstewart » Sat Aug 13, 2016 1:26 pm

I am having problems with the immobiliser on my 2003 mx5. More times than not it starts ok - the immobilser light comes on when the key is turned and the car starts. Intermittently it does not start and I have to leave it for some time - probably several hours although I haven't timed it - before it does. The immobiliser light on the dash sometimes comes up with the code - two long flashes then four short flashes - repeated, even when the key is removed.

Anybody have any idea what this signifies and how it can be fixed.
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Re: Immobiliser flashing fault codes

Postby drumtochty » Sat Aug 13, 2016 1:53 pm

The immobiliser is paired with the ecu and the ignition keys.

Therefore once solution is a secondhand ecu and immobiliser unit and keys the numbers on the ECU must match with the replacement.

This is where there are two different routes some mk2.5 cars have a single code transponder chip in the key so you get keys recut at Timpsons with the new key electronic number writen to the virgin transponder number and the old key shape cut to unlock the steering lock after cganing the ECU and immobiliser.

Later cars have a rolling key code and in this case you will have to change the steering lock to the one from the original donor car so that it uses those keys.

The ecu is where the passengers feet would be. By any chance have you lifted the passenger side carpet as if the drains behind the seatbelt towers are blocked, water would have got the the ecu.

Lift the carpet and see if the wiring to the ecu is wet.

Drying it out may sort things as you say it is intermittent!!!!!!!!!!!!!!!

Autolink may be able to help with a replacement ecu, immobiliser and key set.
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Re: Immobiliser flashing fault codes

Postby drumtochty » Sat Aug 13, 2016 1:59 pm

http://www.autolinkmx5.com/ecu-bp6m-wit ... 5835-p.asp

There is one at autolink note the number on the ECU but they are saying here that it is a single code key code.

That is not always the case.
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Re: Immobiliser flashing fault codes

Postby wstewart » Mon Aug 15, 2016 12:38 pm

Thanks Drumtochty. I did check the footwell and it seemed ok. However I will check it again with all this rain!! Armed with all the info you have given me I can speak to the autoelectrician to get this fixed.

Regards

Stewart
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Re: Immobiliser flashing fault codes

Postby drumtochty » Mon Aug 15, 2016 7:33 pm

Are you saying you lifted the carpet and checked the wiring for dampness.

The carpet is waterproof and you cannot feel any dampness without lifting it.
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