Cobra immobiliser, general questions.
T i m
I've bought a couple of touch-key Cobra 8510 immobiliser's and fitted
one to daughters b/f's HiLux and it went ok (we may add an electric
fuel pump to it later as well).
Whilst installing I noted it had two switched live inputs and I called
Cobra to ask:
1) Why? (they couldn't tell me but gave me the number of their 'man
tech man' who I've yet to speak with)
and
2) What would happen if they were connected to two different fused
switched live ccts (if that was the 'point', to minimise the risk of
the vehicle being auto-immobilised whist in motion) and a fault was to
develop on one cct that caused the fuse to blow (to protect the cct).
... wouldn't the secondary feed then effectively bypass the fuse on
the first cct and cause the fuse in the second cct to blow (in any
case), or if they weren't both fused, melt some wiring? [1]
If it was simply to provide some extra wires to make the job of
bypassing it more time consuming then I could just join them together
and pick up a switched live feed from anywhere on the ignition as if
that goes dead you wouldn't have any ignition in the first place?
A second question from that then. We now have the Mk3 Astra back
(stolen / recovered) and I intend fitting the other Cobra system to
that (FWIW etc). Where would be good points to immobilise that please
as at least it has an ECU that (presumably) couldn't easily be
hotwired otherwise.
The 8510 has dual ccts that are 'made' when disarmed.
Cheers, T i m
[1] A diode in each leg would prevent that of course.
Paul
> Hi all,
>
>
> I've bought a couple of touch-key Cobra 8510 immobiliser's and fitted
> one to daughters b/f's HiLux and it went ok (we may add an electric
> fuel pump to it later as well).
>
> Whilst installing I noted it had two switched live inputs and I called
> Cobra to ask:
Any use:
http://1.bp.blogspot.com/_Eq-HZ51C5qk/S-q4a_IdKKI/AAAAAAAAAOM/LbV1nb3bQ5U/s1600/a8510.jpg
It shows a permanent live and a pair of wires to go to ign switched live.
Both the latter and the grounds need to be connected "30mm apart"
which I read as connect the switched live to switched 12v and the other
to the same wire 30mm away.
No idea what this is supposed to achieve? Some sort of voltage drop
detection? Wierd.
T i m
wrote:
>> I've bought a couple of touch-key Cobra 8510 immobiliser's and fitted
>> one to daughters b/f's HiLux and it went ok (we may add an electric
>> fuel pump to it later as well).
>>
>> Whilst installing I noted it had two switched live inputs and I called
>> Cobra to ask:
>
>Any use:
>http://1.bp.blogspot.com/_Eq-HZ51C5qk/S-q4a_IdKKI/AAAAAAAAAOM/LbV1nb3bQ5U/s1600/a8510.jpg
Yup, that's pretty well the diagram we have in the installation
'manual' (if 3 pages of A6 text could be considered such). ;-)
>
>It shows a permanent live and a pair of wires to go to ign switched live.
>
>Both the latter and the grounds need to be connected "30mm apart"
>which I read as connect the switched live to switched 12v and the other
>to the same wire 30mm away.
Ok, however that 30mm thing is not mentioned on the paperwork that
came with mine (only a few days old).
>
>No idea what this is supposed to achieve? Some sort of voltage drop
>detection? Wierd.
In light of your finding re that diagram and the 30mm thing that sorta
answers my question re what would happen if you were to end up with
both feeds on different fused ccts (unlikely to be the case if only
30mm apart etc). I wonder if (re the switched live feeds) it's just to
ensure you make a good connection (twice the chance of making a good
connection)?
Or I wonder if the 30mm reference to the switched feed connections is
just a typo that's been carried over from the immobiliser text? i.e. I
can see why you would make a bigger gap than just a cut on the
circuits you are trying to immobilise ... so the thief can't re-join
them easily etc.
What was funny (not) was when I called their support line:
M: Could you tell me why there are two switched live feeds (+15's) on
the 8510 immobiliser please?
C: There aren't.
M: Erm there are on mine?
C: There aren't:
M: Erm, I've just wired a new one up on the bench to test it pre
fitting and I can assure you there are and as confirmed by the manual?
C: Let me get a manual and check .... oh, you are right ... erm, I
dunno.
;-)
Cheers, T i m
Paul
Unless the +15v is in and out of the cobra (with as you say a gap of
30mm to prevent reconnecting as you said) - so effectively the cobra
switches the accesory circuit - so if the crook forces the ignition
lock, he won't be able to start it because of the immobobiser circuit,
but he *also* won't be able to pop an electric boot and steal contents?
T i m
wrote:
>Unless the +15v is in and out of the cobra
It is, we checked. ;-(
My thought is that if I took the +15 from somewhere near the live feed
to the ignition cct (x2, 30mm apart <g>) then if the power goes to
that point then I won't have any ignition in the first place (from a
safety perspective here).
>(with as you say a gap of
>30mm to prevent reconnecting as you said) - so effectively the cobra
>switches the accesory circuit - so if the crook forces the ignition
>lock, he won't be able to start it because of the immobobiser circuit,
>but he *also* won't be able to pop an electric boot and steal contents?
I'm cautious of the fact that the immobiliser is only rated to 10A per
cct so I wouldn't want to switch the entire switched live output like
that.
So, it's just to add a deterrent by having what looks like an actual
alarm / immobiliser device (rather than a dummy flashing led etc) and
some difficulty to their day by killing say the LT feed to the actual
ignition and / or starter / electric fuel pump / crank sensor / other?
My idea is that if they go so far as actually breaking into the thing
again and attempting to drive it off that it /nearly/ starts but
doesn't. The longer I can keep them occupied the better chance of them
being spotted by a passer by.
On that then, what sensor could I cut that would let it say start but
not rev / run properly?
Cheers, T i m