Omega Owners Forum

Omega Help Area => Omega Electrical and Audio Help => Topic started by: countrywoman on 07 February 2021, 14:28:32

Title: alarm/immobiliser unit
Post by: countrywoman on 07 February 2021, 14:28:32
Is the alarm/ immobiliser built into the centre locking unit? and there are 2 relays behind glove box , small one that's connected to indicators and a large red one that haven't figured out yet. Any idea what effect removing rear door locks , boot and fuel flap locks will have on system. 
Title: Re: alarm/immobiliser unit
Post by: Nick W on 07 February 2021, 14:38:57
Is the alarm/ immobiliser built into the centre locking unit? and there are 2 relays behind glove box , small one that's connected to indicators and a large red one that haven't figured out yet. Any idea what effect removing rear door locks , boot and fuel flap locks will have on system.




The immobiliser is part of the engine ECU, and works off a chip fitted in the key, read by a gadget around the ignition lock.


The alarm is independent, and is operated by the remote control fob. It also operates the central locking. You can disconnect faulty lock solenoids, and the rest of the system works without noticing. The driver's door solenoid does have a micro-switch which can cause problems if not fitted/faulty.


In your situation, I would have used the wiring loom from a much simpler car, with the Omega engine ECU connected to it.
Title: Re: alarm/immobiliser unit
Post by: countrywoman on 07 February 2021, 15:32:06
Thats what I thought, its the alarm unit I was not sure off.Trouble with the wiring diagram that it does not match reality, wires shown going to lets say no 432 so look on sheet 400 and then there is no wire to connection 432 . No wonder I am confused!!
Title: Re: alarm/immobiliser unit
Post by: Doctor Gollum on 07 February 2021, 16:35:16
Look again and take your time. The pinnouts are correct even if the colours are different.

Also there are two sets of diagram... One is '94-'96.5 (early models), tother is '97-'00 (later models), so you really need to be sure that you are using the correct one for the donor car.
Title: Re: alarm/immobiliser unit
Post by: countrywoman on 07 February 2021, 16:53:34
I will get there even if its down to chasing wires , so far its a blend of book, chasing and the under bonnet relay pic. Okay so does the "burglar alarm " affect the immobiliser ??
Title: Re: alarm/immobiliser unit
Post by: Doctor Gollum on 07 February 2021, 17:08:32
Nope. Separate systems.
Title: Re: alarm/immobiliser unit
Post by: Stu.C on 07 February 2021, 23:50:44
(https://www.cuyahoga.co.uk/wp-content/uploads/2021/02/20210207_234535.jpg)

Turns out it really doesn't need a lot to get it to run. Compared to the amount of time I spent getting the engine and entire loom out of the car, the first test fire on the trolley was relatively straightforward;


 :y
Title: Re: alarm/immobiliser unit
Post by: Nick W on 08 February 2021, 09:31:51
It doesn't take much more work to get it running with just the engine loom, without the rest of the car.
Which is what you want for engine swaps.
Title: Re: alarm/immobiliser unit
Post by: Stu.C on 08 February 2021, 11:16:35
It doesn't take much more work to get it running with just the engine loom, without the rest of the car.
Which is what you want for engine swaps.

Exactly. I'm basically building a test rig because I'm in no rush and can use it to run the engine, strip the loom of unnecessary bits a little at a time and rinse & repeat until I'm down to the minimal wiring needed. It's way beyond the level of work I've done on a car before, so a cautious learning approach works for me - rather than just chucking the lot into a shell a year down the line and crossing my fingers.  ;D

Builds like Ian's MGB and the various Scimitar projects have become my bibles  :y
Title: Re: alarm/immobiliser unit
Post by: countrywoman on 08 February 2021, 11:17:24
That bit is not the "problem" it was getting the central locking working plus taking as much unnecessary stuff out of the loom without upsetting things. There are 2 relays behind glove box in Omega that still not worked out if they can be deleted , think they might both have something to do with alarm? and I dont need that.
TBH have it nearly all sorted , using the light /wiper switches/wiring and stuff but that was easy. If there was a way to work the centre locking without the control unit I would .
Title: Re: alarm/immobiliser unit
Post by: Stu.C on 08 February 2021, 11:37:27
The red one is the Servotronic relay for the power steering, that apparently varies the assistance based on engine speed - http://www.omegaowners.com/forum/index.php?topic=90682.msg1155659#msg1155659 (http://www.omegaowners.com/forum/index.php?topic=90682.msg1155659#msg1155659)

Nice description of its operation here from Kevin Wood, purely as I was intrigued - http://www.omegaowners.com/forum/index.php?topic=133171.msg1706600#msg1706600 (http://www.omegaowners.com/forum/index.php?topic=133171.msg1706600#msg1706600)

Title: Re: alarm/immobiliser unit
Post by: Nick W on 08 February 2021, 11:53:19
That's where we differ; there's so much electrical stuff in an Omega that I wouldn't use, or needs to be modified so much that starting with other components would be a better solution(heater, instruments etc), that I wouldn't bother removing the body loom from the donor.


Other reasons for this are the sheer size of some of the parts; the fuse boxes and their locations would be a problem in any car I might build.


I have re-wired cars with generic kit-car looms, but the simple ones I used are NLA, and others are at least twice the price. I would be more likely to use a mk3/4 Metro loom now, as it's simple, uses components that I would be using anyway, has remote central locking that is easily used, and is already wired for stand alone EFI. It also uses readily available multi-connectors for parts like lights, column switches, so patch leads are easy to make. Fuse box is about the size of a paperback book, has the OBD connecter, and will fit under the dash near the driver's right knee. Most grounds are made with a multi-plug that bolts to the body work. It's easily removed from the car and cheap which are big advantages.


But we all have different ways of doing jobs this, and wiring is one of the worst jobs of building custom cars.
Title: Re: alarm/immobiliser unit
Post by: countrywoman on 08 February 2021, 12:48:11
Found the cause of some of the confusion, as this is a P reg reckoned it was an early car, turns out its first of the later with alarm built into central locking unit . Red relay can get f**** of then and the one next to it looks like its alarm relay to flash indicators when armed ? As I have made the central locking loom separate it will be possible to power it up and see if it works.
Title: Re: alarm/immobiliser unit
Post by: TheBoy on 08 February 2021, 14:10:16
Right, 1994/1995 cars with the old IR central locking had immobiliser as part of the central locking, and a relay up behind the glovebox. The immobiliser was essentially a timer which mean you had to start the car within a set time of unlocking.

1996 onwards had an immobiliser ECU on the steering column, which got a signal from a transponder in the key, and sent a coded Permission to Start signal to the engine ECU.


So if the donor engine ECU is from a MY94 or MY95 car (last LETTER of VIN S or T), you can wire out the immobiliser.

If the donor ECU is from a later car, you need the immobiliser ECU and the transpnders.


Hope that helps and clarifies.
Title: Re: alarm/immobiliser unit
Post by: countrywoman on 08 February 2021, 14:50:50
Thanks , got that bit.