immobiliser wont disarm

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j_rov

Active Member
Posts
170
1995 300Tdi

Got an intermittent problem - sometimes i cannot unlock the car and disarm the immob with the fob. It's got new batteries and when it works, will disarm from quite a distance.

So, it's armed now, and blaring away as I had to move it for swmbo so she could get to work.

Where should i start looking to fix this? I'm pretty sure its not the fob as it's in good condition, new batteries and not got anything loose inside.

I'm not looking to bypass it particulalry as the alarm/immob is useful.

Thanks
 
Would that be a single or a two button fob? .. single buttons can be re-programmed by the user, two button fobs can go out of tune ie off frequency. Go to Remotekey's site for more info.

It's a single button style. I've reprogrammed several times. It seems to work fine for a while then stops working (always when locked lol). After a while of not working, it starts working again.
 
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It's a single button style. I've reprogrammed several times. It seems to work find for a while then stops working (always when locked lol). After a while of not working, it starts working again.

I doubt it's the alarm unit, but have a look at to see if the multi pin plug is pluged in fully and the antenna is also that will have a coax tv style plug.
Alarm unit is behind the glovebox.
 
I doubt it's the alarm unit, but have a look at to see if the multi pin plug is pluged in fully and the antenna is also that will have a coax tv style plug.
Alarm unit is behind the glovebox.

thanks, I'll whip it all apart tomorrow and have a look.

beginning to do my head in!

If i unplug, clean and replug will it wipe memory or worse?
 
Discovery 300 tdi has it aswell 2 button remote and sensor up near interior light:)
but i did post before i sae the single button reply :rolleyes:
Mark

You did say "could be sensor in the roof", the tread is about communication between the fob and the alarm ecu and not false alarms due to the ultrasonic movement sensor located below the headlining.

So the D1 does NOT have a sensor in the roof but the D2 does :p
 
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You did say "could be sensor in the roof", the tread is about communication between the fob and the alarm ecu and not false alarms due to the ultrasonic movement sensor located below the headlining.

So the D1 does NOT have a sensor in the roof but the D2 does :p

The thread is about 'Got an intermittent problem - sometimes i cannot unlock the car and disarm the immob with the fob'.
When i had this fault with mine it turned out to be the roof sensor (ultrasonic) if the sensor fails (mine was intermitant)the doors wont unlock from the remote and the imobilliser will not disarm, i could unlock the doors with the key but it still woundnt start, i removed the ultrasonic sensor as it was full of water and replaced it now the doors unlock at the car starts?? and i now carry a spare:D
So my conclusion was the roof ultrasonic also disables the immobilliser but i could be wrong ( not for the first time:):))
Mark
 
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