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2001 25 Immobiliser help please !
Posted: Wed Jan 13, 2021 4:12 pm
by carrottinthesouth
Good afternoon to all, any help or advice gratefully received. Fob has new battery & is activating + deactivating alarm indicator on dash (although only locks drivers door -will not unlock). Whether or not fob used car was starting normally with the key...... until I plugged in a diagnostic reader + erased 2 old fault codes. Now fob or key will extinguish alarm indicator but no starter operation, car battery is good + no effect on headlights ( don`t dim when key turned to start position).
Thanks in anticipation
Simon
Re: 2001 25 Immobiliser help please !
Posted: Wed Jan 13, 2021 7:31 pm
by 220 GSi turbo
A few thoughts:
Original fault is probably the driver's door lock motor or its wiring (including the connector on the edge of the door where the body loom joins it). If not, it could be the 5AS (alarm) control module which is mounted behind the dashboard on the driver's side, right up above the fusebox and below the windscreen. You have nothing to lose by unplugging the 5AS and then reconnecting it, just in case any of the connections are poor (could happen as a result of prolonged damp or condensation in the car).
The 'new' fault may be linked to the original fault if it is the 5AS module that is playing up. Or it could be a coincidence. Check the earths from the battery to the slam panel (first port of call for most electrical issues on 'our' cars!) and if in any doubt remove them, clean and refit. Also check the spade connection on the starter motor (solenoid). When the key is turned to 'start', can you hear the faint click of any relays? The starter motor relay is in the engine bay fusebox, also check fuse 20 in the fusebox under the dash.
Oh, and congratulations on joining the ranks of 25 GTi owners

Re: 2001 25 Immobiliser help please !
Posted: Wed Jan 13, 2021 8:26 pm
by carrottinthesouth
Many thanks `220 GSi Turbo`, will be on the case tomorrow - I was most concerned this was due to me clearing fault codes,(do you know if the ECU is part of the immobiliser process ?) & the fact that the alarm led was off & no sign of starter motor life. There has been some condensation in the car, sorting as a priority.
Thanks for the accolade - I`m very impressed with the torque and driveability of the GTi .
I was VERY sad to let the 220 SLi go - albeit to a SUPERB new home ; on the other hand the GTi is a bit like having a new girlfriend !!
Regards to all & many thanks
Simon
Re: 2001 25 Immobiliser help please !
Posted: Thu Jan 14, 2021 10:20 am
by GTiJohn
Glad your enjoying the GTi
Good luck fixing your immobiliser. It is usually connections or microswitches but if you get to needing reprogramming we have contacts.
Re: 2001 25 Immobiliser help please !
Posted: Fri Jan 15, 2021 4:35 pm
by carrottinthesouth
SORTED - thanks for your help ; spade connector on starter solenoid. Why would it do that to me directly after I`d plugged in the diagnostic reader ?
Co incidences & red herrings all sent to try us.
Re: 2001 25 Immobiliser help please !
Posted: Sat Jan 16, 2021 10:04 am
by GTiJohn
Phew!
Good advice is gold dust!
