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Fitting an immobiliser

Started by WGB, 01 October 2007, 09:10 AM

WGB

As part of my three days in the shed over the Western Australia Long weekend holiday I have been tidying up some paintwork glitches on the 6.9 (Shot the clear-coat today on the panel I was patching, generally checking the car over and fixing rattles.

I have re-built the centre consiole and fabricated a few support pieces that were missing from the structure and I am fitting an engine immobiliser - which is a requirement for registration in Western Australia - tidied up some engine bay wiring and ordered new plug leads.

I have a very easy to use transponder immobiliser which turns off by detecting (Via an aerial placed in the dash) a small transponder that fits on the keyring - as soon as the ignition is turned on.

I can immobilise two circuits with this immobiliser and have sorted the fuel pump on one circuit but would like to put the other circuit on the gearbox inhibitor switch as it is a simple low current earth switch.

The workshop manual (USA model) shows the starter relay as the front one of the two in the fuse box (the rear one is the fuel pump relay) but the brown earth wire in the USA wiring diagram coming from this relay has a yellow stripe and goes to earth via the starter inhibitor switch - making it extremely easy to divide it and make it a switching point.

The two euro's I have at home 450 and 6.9 both have a plain brown wire coming from this terminal and when I hook up the battery I can see if it controls the starter but I wonder if anybody knows whether this travels via the inhibitor switch or whether there is some other easily accessible point to interrupt the starter motor switching.

Bill

koan

Quote from: WGB on 01 October 2007, 09:10 AM

...circuit on the gearbox inhibitor switch as it is a simple low current earth switch.


Not sure about that, I believe the inhibitor switch is in the 12V line to the starter solenoid, the other side of the solenoid goes to earth through the starter case.

Quote

The workshop manual (USA model) shows the starter relay as the front one of the two in the fuse box (the rear one is the fuel pump relay) but the brown earth wire in the USA wiring diagram coming from this relay has a yellow stripe and goes to earth via the starter inhibitor switch - making it extremely easy to divide it and make it a switching point.


The relays are identified by a number on the harness connecting to them, I posted a list of these numbers recently.

I ended up isolating the fuel pump, I looked into the starter solenoid but wasn't sure how it was connected. I have a US electrical trouble shooting manual, I couldn't reconcile the diagrams with my wiring. Something is different, not sure but AUS cars don't seem to have the relay that isolates the A/C compressor when cranking.

koan
Boogity, Boogity, Boogity, Amen!

WGB

There is a space in the fuse box for a third relay which is shown in the picture in the USA manual but they do not say what it is for.

My other 450 has a very effective immobiliser that stops the starter motor from operating but I didn't fit it and I've never found where it is hidden to trace the wiring - perhaps I should start there.

Bill

koan


Brown is always ground on M-B wiring - at least on 116s.

Looking at the US wiring diagram I can't work out what the fuse box third relay is.

My diagram does show a br/yl wire from the coil of relay 4 to the lockout switch to ground so it might be the one.

I had the idea there was another relay on the US diagram in the starter circuit, my confusion might be caused by the relay appearing in two places on the diagram!

My method of changing connections to relays is to prise the socket apart, lift out the desired pin and bend the lead so it comes back out of the base. Replace that pin with a pin from an old socket and run its lead out of the base as well.

(if you want old male and female pins I have a few)

What about removing pin 5 from the starter relay (as described above) and seeing if it connects to ground via the lockout switch in "P" and "N" but not in other PRNDL positions?

(if it's that easy why didn't I work it out before?)

koan

Boogity, Boogity, Boogity, Amen!

WGB

Thanks for the tips Koan.

I have a whole wrecked car full of connectors so no shortage there and I like your idea of the fitting method as I haven't cut any wires yet.

I will see what happens when I interrupt the earth to the ?Starter relay but will be busy for the next few days.

Bill

nathan

Bill,
as the car is over 25 years, you dont have to fit one if you dont want to!
its on the transfer papers
1979 116 6.9 #6436
2018 213 e63
2011 212 e63
2011 463 g55
2007 211 e500 wagen
1995 124 e320 cabriolet
1983 460 300gd
1981 123 280te

WGB

#6
I still like the idea of having one - especially as I had a car stolen from my surgery in Kalamunda some years ago while I was working - but a good reliable installation is very important to longevity and peace of mind.

I still remember the feeling of seeing the empty car park and don't want a repeat.

I also have a set of genuine M-B locking wheel nuts that I originally purchased for an E280 in 1994 at a cost of $176. The bolts are the same but are probably too long for these AMG wheels - I may shorten them as I would not park the car in public without the wheels locked and the immobiliser fitted.

I'm a security freak - try getting into my house if you can get past the Bull Arab in the drive way ;D

Bill

nathan

i think their is a better chance of me being sniped from 100 yards than successfully entering casa del babe un noticed!
1979 116 6.9 #6436
2018 213 e63
2011 212 e63
2011 463 g55
2007 211 e500 wagen
1995 124 e320 cabriolet
1983 460 300gd
1981 123 280te