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#565399 - 11/03/19 09:59 AM 3.9/ 4.6 Plus 8 Immobiliser Issues
smudger1 Offline
L - Learner Plates On

Registered: 20/05/09
Posts: 168
Loc: Durham, UK

To all members who have the “Green Box” 10AS Immobiliser which is located behind the dash I would like to share with you some intermittent issues I was having with this bit of kit.

In essence I sent the box away to Unsurprisingly the factory had not reprogrammed the Immobiliser to suit the archaïque nature of a Morgan, rather than go through everything from scratch I have simply added the covering note I sent in with the box, and the Email response from Paul Brown at Technozen.

This guy is very easy to talk to and has an in depth knowledge of the Lucas 10AS Module, what will surprise you , is his rates (Pleasantly )



1999 Morgan 3.9 Immobiliser

I called earlier to day & went through a couple of problems encountered with this unit , the unit is fitted to a Morgan so a lot of the functions such as flashing lights , door locks should be defunct as they don't apply – the only function as far as I determine is to prevent/ allow the engine to start. This Immobiliser was partnered with a a “Spider Unit” but due to issues with dry soldered joints I removed it and replaced it with a bypass plug
I'll to go over the faults again:-

Intermittent Fault 1

This has happened now and again over the years, probably manifested itself about fifteen years ago there is no impact on the operation of the immobiliser there is simply a sound like a flasher relay ticking away , if I switch of the battery using the isolation switch , then switch it on again there is no effect on the ticking/clicking I have even left it switched off overnight to no avail. Then all of a sudden it'll just stop - before this started again last October it must have been about 10 years since the last occurrence

Intermittent Fault 2

The car has a dashboard LED which flashes rapidly when the key fob is activated to mobilise the car , after about 20 seconds the LED flash will slow the down to something like a 3-5 second interval.
After being in the garage for 3-4 months over winter and probably started 2- 3 times over that period.

I went to start the car this week ( left with a trickle charger during the winter) when I switched on the ignition the LED came on constantly & the engine refused to start . After isolating the battery a few times It did start ok , but i'm concerned incase I get stranded .

One other thing, I very rarely use the Immobiliser and a few times last year the the Dashboard LED was flashing at its 3-5 second interval although I couldn't remember arming it ? but couldn't swear to this .

I don't know what is involved with your testing procedure is but in relation to fault 2, would suggest if you have the capacity to do so , try leaving the unit powered up overnight with it unarmed, then try the the next night with it armed in an attempt to induce the intermittent fault



Hi Alan,

I received the 10AS module and fobs, it has been on test for an extended period
and my findings are that this module is not faulty.

However the settings are not suitable to a vehicle that has no central locking.

Your detail of Fault 1 suggests that the 10AS was in alarm mode, when activated the
module will sound the vehicle horn and flash the indicators. The relay clicking that
you heard was the internal relay that drives the indicator circuits.

With regard to Fault 2, I suspect that this was due to the fact that the Passive Immobilisation
option was enabled, this was a safeguard feature in that if the driver forgot to arm the
system it would enable the immobiliser after a few minutes.

The 10AS was originally developed for use in the Land Rover Defender and
Discovery and the software has an option to choose either model, this sets
a number of base settings.

The Discovery always had central locking fitted and the door motor/lock units
provide feedback to the 10AS and this feedback must be present, if missing
the 10AS will behave erratically. I suspect this was the cause of Fault 1.

The Defender had central locking as an option and this would be a better choice
for a vehicle that does not have central locking fitted, as the lack of door motor/
lock units will not affect the rest of the module's operation.

Your module was set as a Discovery.

Given the above I have made the following changes...

The module is now set as a Defender.

The Passive Immobiliser option has been disabled, the immobiliser will only activate
when you choose by operating the fob.

I have removed the internal central locking relay and replaced it with a small sounder.
On arming the system the sounder will emit three sort tones, the dash LED will flash rapidly
and after 10 seconds will settle to a slow flash rate of about once per second.

A slow flashing LED or the LED constantly lit on ignition is indicative of an armed system, pressing
the fob unlock button will always deactivate the 10AS.
This will now be signified by a long tone.

The cost for the work carried out and return delivery is £25.

I can accept payment via Paypal, my account email is:

1999 Morgan Plus 8. 3.9 ....
1961 Alvis TD21 Series1 3 Litre Auto....

#565403 - 11/03/19 10:15 AM Re: 3.9/ 4.6 Plus 8 Immobiliser Issues [Re: smudger1]
Richard Wood Offline
Talk Morgan Enthusiast

Registered: 03/02/16
Posts: 1630
Loc: East Harling, Norfolk UK
Always gives the feel good factor if you find a specialist technician who knows what he's talking about. Hope his work and clear thinking fixes your issue.

2018 Roadster - Red/Magnolia - "Morton"
1967 Land Rover series 2a SWB
1960 Velocette Venom

#565408 - 11/03/19 10:30 AM Re: 3.9/ 4.6 Plus 8 Immobiliser Issues [Re: smudger1]
James B W Offline

Has a lot to Say!

Registered: 31/07/14
Posts: 1204
Loc: Newcastle Upon Tyne
thanks for posting this Alan and I hope the repairs have the desired effect.

I have bookmarked the website for Paul as it is nigh on impossible to find people capable/willing to investigate electronic faults - and at a very decent price to boot thumbs

The Aero8, Series 1 has a number of 'one off' electronics that are no longer available from the factory so Paul may be a future option....

Aero8 , Series 1 - Boston Green
Range Rover Evoque
Smart Brabus Convertible

#565417 - 11/03/19 11:57 AM Re: 3.9/ 4.6 Plus 8 Immobiliser Issues [Re: smudger1]
MOG 615 Offline

Has a lot to Say!

Registered: 24/09/14
Posts: 1350
Loc: London

Many thanks for posting this. I have experienced almost identical issues to you, and it is great to know that there is a solution, and at a reasonable price. I was beginning to think that I would have to live with it forever.
Andy G
1999 +8 , Indigo Blue.
Ex-John McKecknie/Mike Duncan 1955 +4 racer.

#567718 - 21/03/19 03:56 AM Re: 3.9/ 4.6 Plus 8 Immobiliser Issues [Re: smudger1]
MGDave Offline
Learner Plates Off!

Registered: 08/04/10
Posts: 377
Loc: South Ontario, from Lancashire...
Hi Alan
Thanks for the info, I’ve also experienced same issues especially the ticking noise. Eventually it went away but I’m sure it’ll return someday soon. At least I can now formulate a plan.🍻
98 +8 Corsa Red
74 MGB Red


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