Wire to cut for immobilizer?

[Coachwhip]

Hi,

New to this section as I've been fixing the v70. Anyway, I've got myself a 240 now. I've just fixed the rear lights, the heater motor (arse) and some welding.
Now however I'm fitting an alarm. Most fitted, just got to extend wiring for drivers for motor and fit immobilizer. I've thought about going into the fuel pump wires, I've found the fuel pump relay but am unsure at the moment which wires to cut. I don't fancy pulling up all the carpets again to see which goes to the pump. Any idea which ones I need to address?

If not I'll get the carpets up again and trace wires back from the tank.

Thanks

Mike

[Bugjam1999]

Hi,

This page should prove useful:

https://www.240turbo.com/volvorelays.html

My personal approach would be to wire the immobiliser into the wire that provides the switching current for the relay, rather than cutting into the wire that provides power to the pumps.

Cheers

[loki_the_glt]

There is an alternative, which involves accessing the plug/socket for the automatic transmission inhibitor. Once I locate the instructions for the Volvo Alarm system I'll post further details.

There is a two-pin multiplug under the dash that on manual cars is effectively a redundant loop, whilst on automatics it links to the gear position selector to inhibit starting in gear. By breaking into this you can run the cables through a switch hidden somewhere in the passenger compartment.

[Clan]

Originally Posted by Coachwhip

Hi,

New to this section as I've been fixing the v70. Anyway, I've got myself a 240 now. I've just fixed the rear lights, the heater motor (arse) and some welding.
Now however I'm fitting an alarm. Most fitted, just got to extend wiring for drivers for motor and fit immobilizer. I've thought about going into the fuel pump wires, I've found the fuel pump relay but am unsure at the moment which wires to cut. I don't fancy pulling up all the carpets again to see which goes to the pump. Any idea which ones I need to address?

If not I'll get the carpets up again and trace wires back from the tank.

Thanks

Mike

It has always been traditional with a Thatcham approved immobiliser to cut 3 circuits with the supplied relay/s
The starter motor
The fuel pump
The ecu feed ,

the wires should be hidden with no signs of the modifications to the loom .

[Coachwhip]

Cheers for the advice. The relay page is really helpful. I'll soon get it sorted then. Cutting the trigger wire is certainly the way forward.
Only a fairly basic alarm so not much wiring but better than nothing. It won't stop someone who wants the car, but it might make an opportunistic thief think twice.

Weirdly though, but then my car is UK not US spec. I have a green relay when that site says it should be white. Having said that, they've probably had a failure in the past and just chucked one on from a scrapyard.

The auto inhibitor sounds interesting as a backup switch to confuse the criminal. Mines a manual but I assume once you cut into circuit it'll act the same way.

Thanks again

[loki_the_glt]

Originally Posted by Coachwhip

The auto inhibitor sounds interesting as a backup switch to confuse the criminal. Mines a manual but I assume once you cut into circuit it'll act the same way.

It does - I tried it by simply disconnecting the plug on one of my manual cars.

[Coachwhip]

Alarm fully fitted, all 4 doors on central locking now, immobilizer hooked up. Old school (ish) radio in. Exhaust being done on Tuesday.

Still gearbox to recondition and sunroof alignment to be sorted. Slowly getting there.

Thanks for the advice.

Mike