Immobiliser activating when driving…

[mattrosersv]

Drove 70 miles to work fine. On way home, from start up, immobiliser was activating after 17sec while driving (same time you get to start the car for first time) .
Drove back with car stalling every 17seconds and having to hit fob and it bump started itself again..

This is the second time this has happened recently. First time I changed big fuse on a hunch (and I had one kicking around) and it went away. So it was either this or disconnecting battery reset something.

Anyone know where the immobiliser gets the signal that the engine is now running from?

Cheers,

Matt

[mattrosersv]

Fuse is good so I am looking at whatever tells the immobiliser the engine is running..?

[Byker28i]

I've had this, as have several others. It's a sign that the imobiliser is failing - time to sort out a replacement from the specialists.
Dave Fairclough - HF solutions, also very knowledgeable. They did mine when it failed, came out to my house.
https://www.hf-solutions.co.uk/immobiliser/4586328...

or there is also
Abacus Alarms
https://abacusalarms.co.uk/alarmshop/car-alarms/tv...


Mine used to trigger and it would kill the fuel pump when driving, not good when it happened on the M4 at rushhour.
If it won't reset, I found I had to disconnect the battery for a couple of minutes to reset it...

[RUSSELLM]

Out of interest, whenn it goes off, is it cutting the ignition, the fuel pump or both ?

[Polly Grigora]

Taken from diagrams that are sometimes proven to be incorrect

For VW type fusebox - Oblong in shape with 1 single row of fuses

Ignition supply from Fuse 12, exits fusebox @ Plug C aperture 15a (Green cable)



Battery supply from Fuse 3, exits fusebox @ Plug G aperture 30a (Red cable)



Earths @ immobiliser also need to be proven good

[mattrosersv]

RUSSELLM said:

Out of interest, whenn it goes off, is it cutting the ignition, the fuel pump or both ?

Thanks All. I don’t know the answer to this yet. Will have to wire the fuel pump with a permanent feed to check.

The starter does not work until the fob is pressed.

Prob won’t get chance to look into this until next week tho

[Byker28i]

On mine I think there were separate circuits/relays cutting each, so the fuel pump was cut when it failed whilst the ignition stayed on, which was proven the first time it did it when I powered the fuel pump whilst looking for what I thought was a fault in the wiring.

Obviously details are sketchy, and also why the wiring is all black wires

[Polly Grigora]

A test lamp or lamps connected between immobiliser ignion sensing cable and earth and also battery positive supply and earth while driving will reveal all

ignion sensing is the future

Edited by Polly Grigora on Saturday 11th June 15:28