help on installing immobiliser on w124

[shirubaby]

Hi Folks
I have a 1989 300ce coupe. And I dont think there is a factory fitted immobiliser on it.... I bought an immobiliser on ebay...fairly decent on. But I need some advice on a few things before I commence on installing it.
Has anybody fitted an immobiliser before? Can you share you experience with me please?

My motives: Not bothered about insurance...just piece of mind that I've installed a security device that I can diagnose and fix if things go wrong.

So my questions are:
1/ There are 2 circuits to be cut on the 300ce and run through the immobiliser. one is the fuel pump feed (or relay) and the other is the started motor circuit.
Am I right in assuming the feed to the fuel pump runs through the interior of the car, underneath the front and back seats? Where is the best place to cut the wire? And what does this wire look like?

2/ Where is the best place to cut the started motor circuit?

3/ How do you attach the '12v ignition wire' of the immobiliser the the ignition barrel (as there are many wires coming out of this one).

4/ The immobilser relays can take an 18A current - from the circuits that I've mentioned above. Is this adequate? Also the wires of the immobiliser are thinner than what I expect for high current circuits like the starter and fuel pump. Maybe there is another way to break these circuits? OR other circuits?


Any advice is greatly appreciated


Shiru

 

[television]

for starters you wire into the fuse relay box, you have a fuel pump relay, and you use the input side for the alarm, you do the same with the starter relay.
A volt meter will give you the live on the switch.

Malcolm

 

[shirubaby]

Thanks Malcolm, - always glad to hear from you.

I think I've sussed out the location of the input side of the started relay.
So cutting it and re-routing it through the immobiliser is fine. Details if anyone wants it.

But can I not cut the output side of the fuel pump relay (i.e. wires going into the pump itself)? Would this be too much for the immobiliser to handle?
The reason I ask it that the fuel pump wire runs under the driver-side seats (much easier to get access to)...
What do you think?

Shiru

 

[shirubaby]

I think I've just answered my own question (with help from Malcolm):

The input side fuel pump relay is "fused" so it IS the best place to cut the circuit.

 

[television]

The fuel pump can use up to 6-8amps if the alarm cant handle that you can always add a relay, If you do make sure you use the default possition (open contacts) when the alarm is set. If you can get to the fuel pump relay the input is pin 30.

Malcolm

 

[Bolide]

Easy immobiliser

OK, here's what I'd do

If your car has the ATA immobiliser it has a grey box under the passenger footwell. Just lift the carpet & floor panel then unscrew the metal floor panel and you'll see it. The starter immobiliser feed passes through this box

Either cut the cable on the way in and route it via a switch, or dump the box and wire the pin to a black mometary pushbutton under the dash and earth the other side of the switch

This way the starter won't turn unless you've pressed the button. Easy immobiliser: nothing to go wrong. All the wire does is to provide an earth. So the switch just gives an earth to activate the starter circuit. Press the button, turn the key and the car will start

I've done all the hard work - you just lift a carpet and fit one switch!


Nick Froome
www.w124.co.uk

 

[shirubaby]

Sweet idea...wish I thought of that before I went out and bought this cat2 immobiliser. D'oh!
I'm gonna fit it (silly not to) and will let you know how it goes. Good point about checking if this has got an immobiliser already.

Question: can an ACC feed for the alarm be gotten from the ACC feed to the radio? The only problem I can think of with this is, if the feed is fused and the fuse goes then my car is immobilised!

 

[television]

Sweet idea...wish I thought of that before I went out and bought this cat2 immobiliser. D'oh!
I'm gonna fit it (silly not to) and will let you know how it goes. Good point about checking if this has got an immobiliser already.

Question: can an ACC feed for the alarm be gotten from the ACC feed to the radio? The only problem I can think of with this is, if the feed is fused and the fuse goes then my car is immobilised!

We are lucky in having Bolide helping,you always get a good practical answer.
The live feed must be fused, that's how fires start, there must be a live fused feed inside the grey box.

Malcolm

 

[shirubaby]

there is a 12v fused supply that is required for the immobiliser. This is what, I assume, gives it the juice. I plan to connect this directly to the battery (fused of course). The acc feed, I bet, is for the arming of the immobiliser. If the immobiliser doesnt see 12v on ACC then it assumes the key is not in the ignition and auto-arms itself. The instructions for my immobiliser doesn't say that this has to be fused.

Anyhoo, with the advice from Malcolm and Bolide I am confident enough to give this a go....this weekend (providing it's not freezing and/or raining). Pin 30 (see post above) looks like a possibility.

 

[television]

The wire that arms pin 30 comes from the rear of the ignition switch I think you will find.that is what the key does, put yours in serries and there you are.

malcolm

 

[shirubaby]

success! Installed, working for a month now.

 

[evo-number-one]

Immobiliser or imobiliser/alarm

If your car has the ATA immobiliser it has a grey box under the passenger footwell. Just lift the carpet & floor panel then unscrew the metal floor panel and you'll see it.
Nick Froome
www.w124.co.uk

Nick

I have not got my car at home at the moment to check this, but do you know if immobilisers were ever fitted on their own or was only a complete Alarm/immobiliser combination fitted by MB (I certainly do not have the red light switch on centre Consol).

I have found contradictory info from looking at some old Motoring magazines from 1995, as some of the 'new car' matrices page from that time for my car show that an Alarm was an option extra and some show a tick against an immobiliser and an optional blank box against the Alarm.

Many thanks



Bob
e-n-o

 

[Bolide]

I don't think I can state anything categorically with W124s because there were so many options. I come across new things all the time!

If you check your VIN on the Russian website you'll see if you have ATA

Everything else - particularly the Scorpion alarms with detectors on the A pillars - was a UK dealer retrofit, I think

The Mercedes RCL locking system with the infra-red keys did, I believe, include an immobiliser but would like someone to confirm that

If you want an immobiliser to conform to insurance requirements then fit what they specify. If you want to prevent your car being stolen then garage it. If you want to get it back get a Tracker. I suspect most thefts are done by lifting the car, not driving it away, and an immobiliser is useless if that's the case

Nick Froome
www.w124.co.uk

 

[evo-number-one]

Nick - excellent advice as always, many thanks

If you check your VIN on the Russian website you'll see if you have ATA

The Mercedes RCL locking system with the infra-red keys did, I believe, include an immobiliser but would like someone to confirm that

On entering my VIN in the Russian Website, no ATA is listed, but it does accurately list the locking system with infra-red and I have heard previously that this was combined with an immobiliser. Owners manual does not make reference to this, only the alarm.

Can anyone else confirm this? If this is the case, then I can 'upgrade' to a thatcham 1, rather than have to do so from scratch.

Thanks

Bob
e-n-o

 

[Bolide]

ATA is option code 551: anti-theft warning system [01.11.1978 - 31.03.1998]

Nick Froome
www.w124.co.uk