Removal of old sigma imobiliser alarm unit anyone ?

ukmastiff · Sep 16, 2012

Assuming I can find the actual alarm/immobiliser unit , how likely am I to be able to remove it without imobilising my car.
I understand the old sigma is probably a metal box hidden behind the glove box or elsewhere seperate from the more obvious siren under the bonnet. I need to keep costs down as there are so many jobs and I really want the 25 year old 'one radio key' Sigma alarm/immobiliser gone before it gets me stuck ( and the siren is faulty anyway).

I am fairly electronics minded but really don't know how they cut in wiring wise or what other sneaky ways an immobiliser does its job. It might not be for posting on the web but if anyone has some info to help me I would appreciate it by E-Mail perhaps.

Regards

Mas

zcacogp · Sep 17, 2012

Mas,

Removing alarms and immobilisers is easy, but time-consuming. You'll need to find the control unit (if it's 25 years old it may well pre-date the Thatcham approval process, so may not be a metal box.) You then simply follow the wires from that to the wiring loom, and remove them. Working out which function in the loom has been 'immobilised' is meant to be hard, with the whole schebang disguised by using black wires and black tape, but alarm fitters always give the game away by cutting the loom at one point and running the wire to the control box and the wire back from the control box to the same point. Removing the imobiliser and joining the old wire back up is therefore child's play.

Take your time. Take as much interior trim out as you need to (may be quite a lot). Be methodical. Have a big pot of tea readily available at all times. Re-solder everything properly (don't use chocolate-block connectors!) Use heat-shrink over the newly joined wires. And enjoy it. It really isn't at all hard.

Oli.

ETA: Removing an old alarm is a great time to fit a new alarm, as you can solder the new immobiliser wires in place of the old ones. Thatcham Cat 1 alarms can be bought quite cheaply and a well-installed one will be a useful way of keeping scumbags from nicking off with your (newly re-purchased!) P&J.

ukmastiff · Sep 17, 2012

Thanks , everything youve said seems to confirm what ive read. App this sigma does have tbe metal box , maybe behind glove box as the siren cable disapears down there. A local spark quoted me 50 quid so it may not be worth the hastle ill have to decide. apparently my car has a tracker somewhere too would u believe it lol

zcacogp · Sep 17, 2012

Mas,

It's easy. Really. My 9-year-old nephew could do it (but he is quite smart for a 9-year-old!)

50 quid sounds cheap tho'. I'd question the quality of the work you'd get for that as it is a long job if done well. I suspect he would just remove the control unit (metal box!) and connect the immobiliser wires together at that point, and actually remove very little. That would work, but wouldn't be a pretty way of doing it.

Oli.

ukmastiff · Sep 17, 2012

Being an ex computer engineer (all be it a long time ago ) that side of it doesnt worry me , its just the fiddle of finding it getting to the wires wherever etc. Ill have a snoop around it and decide either way. I found the fault in the siren unit so have disconnected that and put the alarm in valet mode but its old and has one remote. For the cost of another id rather remove it and start again before it lets me down !

The fumes are the prioriy though followed by rear seat belts as the kids are furious

Mas

JamesBall · Sep 17, 2012

Mas, regarding the rear belts - I got 3-point belts fitted (replacing the lap belts) in the black 944T at http://www.quickfitsbs.com for I think about £200 (might have been less) and they seems like very good guys.

ukmastiff · Sep 17, 2012

Ta , its the same company i contacted before i sold the car [

] , maybe ill actually do it this time hehe

Mas

Chrishazle · Sep 17, 2012

There was a tracker in my 968 cab when I bought it - found it screwed to the plywood plank in the passenger footwell that hides the ECU! Cliff at Project Nine removed it while fitting the Promax chip.

Hilux · Sep 17, 2012

Just before I sold my 944 the Clifford alrm failed so I had another fitted with the strict proviso that they thoroughly removed all the old alarms and wiring as I had problems before it failed. From my experience a new Thatcham approved alarm isnt a lot of money these days and the company that did it only charged me £160 IIRC - well worth it to get back to reliability.

Here was the result!!