96 disco - immobiliser intermittent fault

Hi

well i think its the immobiliser - problem is we have an intermittent fault
and its difficult to find exactly whats wrong.

basically engine starts first time no probs the rest of the time - battery,
leads and starter cables all ok but on
occasions turn the key and nothing - no starter / solenoid noises or
anything, lights on dash that normally go out briefly when starting /
turning key to the start position go out as normal

have tried resetting alarm then trying again and more by luck than science
it sometimes works

had thought it might have been the ignition switch but seems ok

have briefly checked cables and all seems ok but as its intermittent
difficult to say when moving a particular
plug or cable makes a difference.

a bit of a bummer really

any ideas on how to fault find for immobiliser faults or any known bits that
likely to be the cause

help!!!

d

Usual failure point is the alarm spider. The pcb solder breaks down...

--
Neil

Had exactly the same problem with 110 300 Tdi CSW, two button remote alarm.
A known fault with the spider unit that develops an intermittent refusal to
de-mobilise hence ligyts but no starter action no engagement. Wait a while
and the damn thing starts of its own accord. LR assistance insisted it was
the stater and like an idiot I had it changed £300. Problem still present,
Roberts Country Vehicles and the contributers here came up with the answer.
The upgrading of the spider unit with a LR upgrade, £ 250. Basically it does
away with the installed immobilliser and is replaced with a seperate one,
that links into the alarm. Two green fobs and a master programming fob
complete the upgrade. Pain in the arse is that you wave the fob in the
desired place and two beeps later you have 15 seconds to start car. Switch
off and after5 seconds it arms itself so you have to remove the key and
disarm it agin before going off, irritating when waiting for wife to do
shopping.



John H


"d" <[email protected]> wrote in message
news:[email protected]...
> Hi
>
> well i think its the immobiliser - problem is we have an intermittent
fault
> and its difficult to find exactly whats wrong.
>
> basically engine starts first time no probs the rest of the time -
battery,
> leads and starter cables all ok but on
> occasions turn the key and nothing - no starter / solenoid noises or
> anything, lights on dash that normally go out briefly when starting /
> turning key to the start position go out as normal
>
> have tried resetting alarm then trying again and more by luck than science
> it sometimes works
>
> had thought it might have been the ignition switch but seems ok
>
> have briefly checked cables and all seems ok but as its intermittent
> difficult to say when moving a particular
> plug or cable makes a difference.
>
> a bit of a bummer really
>
> any ideas on how to fault find for immobiliser faults or any known bits
that
> likely to be the cause
>
> help!!!
>
> d
>
>
>
>

"Hirsty's" <[email protected]> wrote in message
news:[email protected]...
> Had exactly the same problem with 110 300 Tdi CSW, two button remote
> alarm.
> A known fault with the spider unit that develops an intermittent refusal
> to
> de-mobilise hence ligyts but no starter action no engagement. Wait a while
> and the damn thing starts of its own accord. LR assistance insisted it was
> the stater and like an idiot I had it changed £300. Problem still
> present,
> Roberts Country Vehicles and the contributers here came up with the
> answer.
> The upgrading of the spider unit with a LR upgrade, £ 250. Basically it
> does
> away with the installed immobilliser and is replaced with a seperate one,
> that links into the alarm. Two green fobs and a master programming fob
> complete the upgrade. Pain in the arse is that you wave the fob in the
> desired place and two beeps later you have 15 seconds to start car. Switch
> off and after5 seconds it arms itself so you have to remove the key and
> disarm it agin before going off, irritating when waiting for wife to do
> shopping.
>
>
>
> John H
>
WTF is a spider unit? My alarm fob (two button) sometimes takes numerous
attempts to unlock the doors and yes sometime the starter motor doesn't turn
immediately the key is turned but if the key is kept turned it does start.
More of an annoyance than a problem.

Peter.

In <[email protected]> Peter Seddon wrote:
> WTF is a spider unit? My alarm fob (two button) sometimes takes
> numerous attempts to unlock the doors and yes sometime the starter
> motor doesn't turn immediately the key is turned but if the key is
> kept turned it does start. More of an annoyance than a problem.

It's a small box that, on a Disco, lives behind the radio underneath a
metal plate. To get to it you have to remove the centre console of the
dashboard.

It switches 3 circuits on when the alarm is deactivated - ignition, fuel
pump and starter. On a diesel it controls the fuel solenoid, the starter
and the fuel pump IIRC.

The problem is that it is so badly made (usually dry joints internally)
that one or more of the circuits become high resistance resulting in a
range of, often intermittent, problems.

On my V8 the first circuit that failed was the fuel pump, we initially
thought it was a problem with the LPG system as it would sometimes
refuse to run when we changed back to petrol. I bypassed this circuit
and installed my own immobiliser into the circuit.

The next circuit to fail was the ignition circuit which caused
intermittent starting - I eventually figured out that the ignition
circuit was so borderline (high resistance) that I got no sparks while
cranking but sometimes it would start if you caught it right as you
stopped cranking after which point it would work OK.

I bypassed the ignition circuit and, again, fitted my own immobiliser.

Now I'm waiting for the starter circuit to fail..... when it does, I'll
bypass that too and maybe fit an aftermarket immobiliser instead - a
Clifford one maybe. I have a bypass wire already installed so that if it
fails I can bypass it quickly and easily.

All my bypasses were done without having to get to the spider - if you
get to the spider and want to remove it altogether, Land Rover supply a
small cable assembly which replaces it - costs about a fiver and saves
tapping into the wiring.

cheers

Dave W.
http://www.yorkshireoffroadclub.net/

hey thanks guys

much appreciate this

will go get one and sort it out - but sounds great fun to replace ha!!!!!

not sure if i fancy changing the whole thing and upgrading though

probably just got with replacing the spider

thanks again

"d" <[email protected]> wrote in message
news:[email protected]...
> Hi
>
> well i think its the immobiliser - problem is we have an intermittent
> fault and its difficult to find exactly whats wrong.
>
> basically engine starts first time no probs the rest of the time -
> battery, leads and starter cables all ok but on
> occasions turn the key and nothing - no starter / solenoid noises or
> anything, lights on dash that normally go out briefly when starting /
> turning key to the start position go out as normal
>
> have tried resetting alarm then trying again and more by luck than science
> it sometimes works
>
> had thought it might have been the ignition switch but seems ok
>
> have briefly checked cables and all seems ok but as its intermittent
> difficult to say when moving a particular
> plug or cable makes a difference.
>
> a bit of a bummer really
>
> any ideas on how to fault find for immobiliser faults or any known bits
> that likely to be the cause
>
> help!!!
>
> d
>
>
>
>

"Dave White" <[email protected]> wrote in message
news:[email protected]...
> In <[email protected]> Peter Seddon wrote:
>> WTF is a spider unit? My alarm fob (two button) sometimes takes
>> numerous attempts to unlock the doors and yes sometime the starter
>> motor doesn't turn immediately the key is turned but if the key is
>> kept turned it does start. More of an annoyance than a problem.
>
> It's a small box that, on a Disco, lives behind the radio underneath a
> metal plate. To get to it you have to remove the centre console of the
> dashboard.
>

snip

> cheers
>
> Dave W.
> http://www.yorkshireoffroadclub.net/

Thanks very much for the info, at the moment all is fine and I can live with
having to press the fob a couple of times, but I'll keep this e-mail as a
reference for the future.

Cheers

Peter