Immobiliser is on the fritz

[redordead]

Got a Mk2 Ph1 172 and been having problems with my immobiliser.

While the key fob is unlocking the doors, half the time I can't get the car started. Called the AA man out a couple of days ago and he checked the charge on the battery and ran a diagnostics check. Both seemed fine. He suggested locking/unlocking the car and waiting a few minutes.

Next day the immobiliser spazzed out again. Bizarrely, the engine wouldn't start when the alarm was off and doors open but I could get it to run whilst the alarm was primed and doors locked.

I know this because the alarm was going off at the same time as the engine running!

Can the immobiliser be reset or repaired? Is it a problem with the key fob? Or would it be cheaper just to bin the factory alarm off and fit an aftermarket one?

Any help will be appreciated!!!!

 

[JuanBoy]

First thing to try is replacing the battery in the key fob. Also try covering the internal sensors if you have them and see if it happens then. Alarm can be reprogrammed to key but it probably cost you 40 - 50 quid. Had similiar symptons with mine and found it to be battery losing charge in the end. Good Luck

 

[BrianR]

First thing.
The alarm and the immobiliser are not connected to each other.

If, when you put the key in the ignition does the led on the instrument pack stays on as a constant light ?

 

[redordead]

No, with the key in the ignition, the red LED in the instrument panel stays on for about 10 seconds, then starts to flash. It goes off if/when the car decides to start.

Can a dying battery in the key fob muck up the immobiliser even though it is operating the central locking without a problem?

 

[BrianR]

The battery in the key has nothing to do with the transponder, thats a passive device. The battery power is only used to work the transmitter that operates the remote locking.

When you get in the car, the LED should be flashing about once per second.

Put the key in the lock and turn it to full Ign, (IE all panel warning lamps on)
As you do this, the LED should stay on constantly, signalling the transponder has been acknowledged and the immobiliser is OFF

Turn the key to the start position and the engine should crank and fire and the LED will go OFF.

Anything other than that is a fault.

The common faults are the reader ring round the ignition lock, or a damaged transponder.

Try your spare key to see if its the damaged transponder.

If that fails to solve the problem, you need to change the transponder reader ring.

Fortunately they are not expensive and they are not part of the coded link, so any replacement doesn't need to be programmed.

 

[DamoWales]

Think your having the same problem i did

It was the ignition relay for me...the red light in the middle at the top wouldnt go out..£20 part from renault

 

[redordead]

Thanks for the help guys.

Wish I had another key to try as that is a nice easy fix - but only got one when I bought the car (second hand)! A few searches on the forum suggest that new transponders are pretty pricey too. Bah...

Spotted quite a few other immobiliser posts since I was last on the forum - must be something in the air screwing them all up!

Whatever the problem, looks like a trip to Renault. Just wanted to avoid that as their prices to 'diagnose' things give me teh fear...

Thanks again for your wisdom. Will let you know what the problem is once I get a spare minute and some spare change to fix it!

 

[redordead]

Just so you guys know - SJ Cooks say that the problem with my immobiliser was a relay.

If anyone else has a problem with theirs, make sure you check it yourselves before having to cough up £80 to be plugged into the Renault diagnostics machine!!!