Disco 1 Possible Immobiliser issue?

MrPorky said:

Hi all.

Have a problem with my Disco. It’s a 1993 200TDI that I have had since new. VIN KAO60346. Hope someone here can help. I apologise for my lengthy initial post but wanted to ensure that I have covered the issues that I have had in the last 5 days.

Recently drove over a rough patch of ground that is used by locals as a free car park. At one point the car rocked side to side quite violently. Should have driven a bit more carefully. I parked the car and operated the central locking system with the door key as I always do (more on that below). All was fine at that point. Ten minutes later I returned and went to unlock the car with my key but the central locking system was not working. Got into the car and tried to start the engine but nothing happened. Starter motor did not function and only heard a click from the footwell relay. All other electrics functioned OK, windows, lights, radio, wipers, indicators, blower, etc. Got the car home on a pick up truck and have been trying to locate the fault since. The car has an immobiliser (factory fitted from new) but its LED indicator is not working at all since this incident.

Have spent several days researching the fault in various LR forums and I think that my problem is related to the immobiliser. I have checked components that I have seen from other reports. All fuses are fine. Found the fused links under the bonnet and they look like new, no corrosion (being in Tenerife for the past 18 years has helped). Tested the micro switch on the drivers door lock and it’s good. The alarm ECU is firmly attached with no signs of external damage. Even tried disconnecting the battery overnight.

I have seen reports about bypassing the immobiliser using the key in the drivers lock but I do not have the four digit EKA code. It's not recorded in the original handbook or any of the other original documents that came with the car. I know that I can get it from mgrccservices.com. I found a couple of youtube videos that suggest you can use a ‘standard’ code (1515) but that didn't do anything and the immobiliser LED indicator is still not working at all. My handbook says that holding the key in the locked position for more that 5 seconds will disable the alarm completely. Tried that also but nothing changed.

My handbook suggests that the ECU (mines an AMR2106) has an internal inertia switch. If it has then the violent rocking, before I parked the car, could have triggered it but I read on the net somewhere that using the key in the steering column lock to start the engine should have rest this anyway and I don’t think that there are any other inertia switches fitted elsewhere.

I always use the key to operate the central locking system. The fob gave up the ghost more that 10 years ago. Tried new batteries and the red light on the fob illuminates but the central locking system does not respond. The fob is the early single button type.

So I am stuck. Don't really want to order a new alarm ECU without knowing if it’s at fault but can’t think of anything else that could be causing these two issues. The only other possibility is to bypass the alarm ECU completely but I do not want to loose the central locking capability and I’m not sure if that is an integral feature of the ECU. If it is not then that is the route I shall take (bypass the ECU) because I don’t really need an immobiliser now anyway given the cars age and I can always fit a kill switch in the cab.

Any help from more knowledgeable Disco specialists would be a big help to me.


Quick update since yesterday. Got the wife to give me a tow start with her Clio. Disco fired up OK so I now believe that's proven my immobiliser theory so may just bypass

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MrPorky said:

Got the wife to give me a tow start with her Clio. Disco fired up OK so I now believe that's proven my immobiliser theory so may just bypass

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sierrafery said:

The fact that it started proves that it was NOT immobilised, the immobiliser would not let it start no matter how much you tow it

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MrPorky said:

why would a tow start not work if the immobiliser was at fault?

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sierrafery said:

AFAIK all kind of immobilisers are cutting the fuel too not just the starter

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MrPorky said:

Thanks for your input but given that the central locking is inoperative, immobiliser led is not functioning and starter won't turn (and these 3 issues occurred at the same time), if it's not the immobilizer what can it be? Just a reminder, it's a 200tdi not a 300tdi.

Sorry for my lack of knowledge on this, but to help me understand your response, why would a tow start not work if the immobiliser was at fault?[/QUOTE
So what makes you think your 1993 200 series disco has a Thatcham approved security system incorporating an engine immobiliser?

Immobiliser weren’t compulsory in the UK until 1998 before that the standard system was an audible alarm although like LR fitting a Thatcham category 1 security system on the 300 series discos (alarm + immobiliser) other manufacturers and installer started fitted the updated security system well before 1998.

So the LED could be a be just indicating that the alarm is set/unset, much the same as the earlier Range Rovers with the LED fitted in the edge of the dash top not in the dash between the speedo and rev counter.
Hopefully the LED isn’t part or the radio cassette unit with anti theft system (CATS).

So engine not cranking, its a simple matter to check the 12v supply from the ignition switch to the relay, then on to the starter solenoid. When fitted, an immobiliser interrupts the starter circuit plus others depending on vehicle, with the D1 models security the system are easy to bypass the with a single wire ‘over lay’ the interrupted circuit, so still retaining the alarm and central locking ECU control.

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sierrafery said:

I really doubt that an immobilised vehicle(no matter which one) can be bump started... i've never heard of engine immobilisation without cutting the fuel supply but i might be wrong

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sierrafery said:

I stand corrected. I made some research and seems that on the '93 D1 200tdi which is equipped with AMR2106(Alarm ECU) this unit cuts only the earth to the starter relay's coil if the alarm is active, the fuel cut-off solenoid is not connected to it so according to the diagram it's possible to be tow started if the starter doesnt work... all you need is to splice in with an earth to the starter relay's coil black/orange(or simple black) wire then it will spin if the problem is from the alarm ECU not something else

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sierrafery said:

I doubt it's the black one, it shoud be the yellow from the left with the white/red and brown thicker wires according to the diagram

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sierrafery said:

I doubt it's the black one, it shoud be the yellow from the left with the white/red and brown thicker wires according to the diagram

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Firebobby1 said:

Hi, sorry but not a disco expert, just another owner. Got any photos of your disco.

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MrPorky said:

Well can now start the motor. So I must have an ECU problem.

All I'm really interested in now is getting the central locking (with key in driver door) back on lline. It will be a shame to lose the alarm though.

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