Alarm installation and drop to earth door switches query

[72BLUE]

As per title, I am fitting an alarm and as I understand it the interior lighting is split into 2 halves on the Stag.

This means that with my drop to earth (DTE) door switches, if I tap in and run wires from each door switch to the SINGLE trigger wire on my alarm, then when one door is opened (when alarm is off) all 6 interior bulbs will light and not just the normal 3.

1) Is this a particularly bad thing? Otherwise I will have to fit a separate DTE door switch either side just for the alarm wires.

2) Is there another way around this?

Cheers
Keith

[marshman]

Not sure if your car is a MK1 or MK2 but be aware that the MK1 door switch is not a DTE type. IIRC it has two wires running to it.

Roger

[72BLUE]

Not sure if your car is a MK1 or MK2 but be aware that the MK1 door switch is not a DTE type. IIRC it has two wires running to it.

Roger

My car is a '73 and did have 2 wire pos feed door switches until my loom burnt. It now has a later loom with single wire DTE type door switches.


Cheers, Keith.

[Firept]

keith.
I had the same problem mine is a MK1. I used a quad opto isolator (http://www.maplin.co.uk/phototransis...-couplers-2198) and arranged it so that the boot and bonnet DTE turned on 2 of the LED's and the switched positive I took from the tunnel cover foot well lights and these fed +12v to the isolator and then just combined the 4 out puts so that it fed the one trigger point on the alarm / central locking control unit works fine. had a few problems with the bonnet switch being a bit too long but soon sorted .
PM me if you need details of the chips wiring etc.

Paul.

[72BLUE]

Oh no, that reminds me, I thought I had nearly finished but I have totally forgot about the bonnet switch!!!

Thanks for the suggestion Paul. That does sound complex for my 'average' ability to understand car electrics! I will have a read up on them.

In the meantime, would it mattter a great deal if I just tapped in my single alarm DTE sensor wire to both DTE door switches? As I see it, all 6 interior bulbs would come on when one of either door is opened. I know it would double the battery drain but surely not by much?

Cheers
Keith

[Firept]

Keith.
If yours is a Mk2, I take it that it is then you could wire them all together but the door switch will now be taking 60Watts instead of 30 Watts (assuming they are all 10 Watt festoon lamps) so you would not want to leave the doors open too long.
or the other way is to use some simple diodes from Maplin that way the doors will remain independent and also when you open the bonnet the lights wont come on either.
If its a Mk1 then that is a different matter and the opto isolator is the way to go.

door alarm.JPG

all the best Paul.

[72BLUE]

Hi Paul, really appreciate the diagram there, great stuff! Now I sort of get diodes, you are coming down to my level a bit more :-) I also see what you mean re 60 Watt festoon lamps, sounds like it is best to keep the split system as is.

Whoops, apologies, scrub my previous comment re forgetting about the bonnet switch, I have just checked and this does not require any extra wiring as it is a spur off the siren that is supposed to be mounted in the engine bay, so all I need for that is a DTE switch. Duhh!

My Stag now has the later MK 2 loom with DTE door switches. The alarm that I am fitting has 3 wires for trigger connections, one is as above from the siren for the bonnet, 2nd is to alarm ECU just for the boot, 3rd is to ECU just for the doors.

Therefore, re your diagram with diodes, I would just need x2 QL78K diodes for the door circuit?

Cheers
Keith.

[Firept]

Keith.
yes that's fine. diodes will just stop the connection between the 2 circuits and keep them isolated. If I remember there's a Maplins near the Station in Crewe.
Glad to be of assistance.
I saw your post ref the door motors but I dont have any pics of mine.
I fitted mine on the door just below the door lock its self and it operates directly on the locking leaver so that it works with either the key or the remote.

I have central locking and alarm unit on mine must get round to putting a motor on the boot lock some time.
Also have Cobra immobiliser as it was part of the Insurance condition this year, unfortunately the central locking/ alarm does not have a Thacham approval.

all the best
Paul.

[72BLUE]

unfortunately the central locking/ alarm does not have a Thacham approval.

The Sigma S30 that I am fitting does have Thatcham Cat 1 approval, but I suppose that is of no use because I think that they have to be fitted by certified installers in order to get the right certificate. I even read somewhere that the alarm has to be checked (and certificate renewed) annually by a pro?

Re the position of your door motors, how is the overall function of the your door locking different to that of Andrews from the other thread?

Cheers, Keith.

[Firept]

Keith.
Same function of the motors just a different place of fitment.
Hmmm... not sure about the certification, some of the installations I have seen by "professionals" has been questionable to say the least.
Even the instructions with the Cobra system if you followed theses to the letter you could have ended up with an interesting bridging of the fuses as they ask for 2 ignition switched supplies, but both wires have the same number on them so therefore I tested out the Cobra on the bench and the 2 wires are joined at the circuit board so treat these 2 sense wires as being a single piece of wire so you needed to be careful where you connect them or you could bridge a fuse. Therefore a fuse could fail legitimately but the circuit is being "fed" from the other connection on the alarm unit not a good situation, seen too many car fires yet this is the way Cobra wanted it connected with no warnings.

I noticed last month Practical Classics were still recommending the use of Scotch lock connectors, now that is a no no! If you need to connect then do it properly and you only have to do it once and it wont fail.

Paul.

[jleyton]

Hi Paul,

Did you take any pictures of your central locking system as you installed it ?

Cheers

Julian

[Firept]

Julian.
Sorry but no it was one of those jobs that needed to be done and a tight time scale as most of my jobs seem to be.
this is the kit I bought 400220051001 of ebay.
The only part I have not used now is the immobiliser relay as I have the Cobra fitted as well and I disconnected the sensor to the brake light which puts the door locks on on the application of the first break press. This was a pain as when you were stopping in traffic to let SWMBO leap out to go to some shop or other of course you have you foot on the break and that keeps the locks on!
It was simple to fit. The main unit is mounted on the relay tray but as you can gather from previous in the post I ended up using the quad opto isolator so that I could get the logic of the door switches to match the logic of the boot and bonnet switches but thats due to mine being Mk1 with the live switching on the door switches, cant say as I like the idea but too much of a pain to change.

Paul.

[DJT]

For anyone with the earlier Mk1 door switches, this is how to get them to act as DTE switches for an alarm/immobiliser. You need two ordinary relays - one for each side.

Immobiliser to Door Switch.pdf

[73stagman]

Your alarm does not need to be fitted by any body special to retain its "Thatcham Cat1" status. That is set by the Thatcham Group. However when you declare that you have a CAT1 system fitted to your Stag to your Insurance company they may want independent verification that it is done properly but that is down to the Insurance company. Your Sigma has an evaluation no as follows TC3 – 1480/0111 and is still on the Thatchams approved list.
Here is a useful link!

http://www.thatcham.org/security/pdfs/categories/PassengerCarCAT1.pdf

[jleyton]

Julian.
Sorry but no it was one of those jobs that needed to be done and a tight time scale as most of my jobs seem to be.
this is the kit I bought 400220051001 of ebay.
The only part I have not used now is the immobiliser relay as I have the Cobra fitted as well and I disconnected the sensor to the brake light which puts the door locks on on the application of the first break press. This was a pain as when you were stopping in traffic to let SWMBO leap out to go to some shop or other of course you have you foot on the break and that keeps the locks on!
It was simple to fit. The main unit is mounted on the relay tray but as you can gather from previous in the post I ended up using the quad opto isolator so that I could get the logic of the door switches to match the logic of the boot and bonnet switches but thats due to mine being Mk1 with the live switching on the door switches, cant say as I like the idea but too much of a pain to change.

Paul.

Thanks Paul,

Although I'm ok at electrics, I'm not sure I could sort out the logics bit and diodes etc remain a bit of a mystery to me

Having said that, I only want central locking, having been marooned in a rather embarrassing place by a dodgy immobiliser once

I see that company supply all sorts of systems so I'll use them if you've found their products good.

Cheers

Julian