Ignition wire for immobiliser

[pierce]

I am fitting a new immobiliser (cobra).
It requires an ignition live, so that the immobiliser knows to re-arm when the van isn't running.
The problem is that all of the ignition lives at the back of the fuse box seem to drop their voltage right down to zero while the starter motor is turning, which is causing the immobiliser to re-arm.
I need to find a live that stays 12v when the ignition barrel is turned.
Its a jx engine, all standard.
I am hoping someone has encountered this before and has a solution.

Thanks in advance.

[Robsey]

There are two spade connections on the back of the fusebox that are ignition live.

You need to look at the block of spades marked as Connector "G".

From memory G2 and G5 should be ignition live.
See my thread on the Map of the CE1 fusebox.

It looks like the connections you found before are on the "X" / relief relay supply. That is live with the ignition on, but not cranking.

Look here
viewtopic.php?t=173773

[pierce]

Thanks Robsey, your fuse box map is nothing less than a work of genius, your advice has given me some hope that I should be able to get this working.

I have created a chicken and the egg situation.

The immobiliser is switching two circuits, one of them must be providing voltage to G2 and G5.

There is a relay in the immobiliser which is triggered by the ignition live, this needs to be on before G2 and G5 give 12v.

So I think the problem is that there is no ignition near the fuse box because I have switched it off with the immobiliser  .

I would have been there all day, thanks for your help. 





 

[pierce]

Yeah that sorted it.
I didn't know the "X" / relief relay supply was a thing, thanks for the info 

[Robsey]

The X-rail or relief relay feed cuts power to the heavy consumers like the head lights, heater motor, heated rear window element during cranking.

- this is to ensure maximum battery to the starter motor and ignition system.

Although it is an old vehicle, the fusebox layout is brilliant for adding upgrades and gadgets.

[pierce]

that makes sense, cheers mate