Immobiliser Issues

Good Morning All,

I know this seems to be a verry covered topic but i cant seem to find the info that i need.

Before i get started the Landy has no SPIDER and no EDC and is a Manual.

I have a 1993 Disco 1 300 TDI that wouldnt start after going wading, i took the Alarm ECU out from behind the glove box, cleaned and dried it out re fitted it central locking worked but car wouldnt turn over just relays clicking.

I read on the net about joining the 2 black/ orange wires together to get it going which worked but i had to unplug and plug back in the alarm ecu every time i wanted to start the car.

Now my question :- is there any way to permanantly bypass the ECU ? im not bothered about the central locking as its an off road toy and i dont need it.

Any help will be greatfully received
Thank you in advance
Regards Rich

Switch the fuel injection pump solenoid straight from the battery. That should get it started.
But also worth remembering is the headlight relay is also in the passenger footwell and will be soaked.

Worth remembering at night.

Ahhhhhhh......... i should have mentioned that it wont crank, fuel side of things is fine as when i unplug the ECU and re fit it, it will crank and start perfectly.

Thank you for the reply......... Since this happened i re located those nice little relays up behind the glove box.

Regards Rich

Lets know what disco u have as 300s weren't around in 1993 it was mid 1994 when the 95MY was introduced and that had the passive immobilising (spider) fitted.
1993 discos have an active immobiliser.

Ok so its an L reg 1994 in that case its definitely a 300tdi without spider and without EDC it has the small Alarm ECU up by the glove box one white plug and one black plug, black plug is all central locking and the white is the Alarm Immobiliser it is on the white one that i have joined the 2 black /orange wires together to get it to start.

I hope that this is enough info....... appologies for the confusion of year.

Regards Rich

Ok early 300 with the black ecu no spider and a single button fob it you have one.
There's a micro switch on the back of the drivers door key barrel operated by a plastic cam this enables you to set or unset the immobilser, so if faulty it can remain in the set position, but using the fob, if you have one should reset the system and allow to start the engine.

But as mentioned a few times the forum a new switched supply to your diesel 'bit' (I'm not a diesel person) and that should be that.

Hi, thanks for the reply, mine is the single button fob but this never worked and got thrown in a drawer somewhere in the house ( as you do ).

If the small cam had become faulty on the drivers door would the central locking still work ?

as far as i can understand they get 2 problems crank but no fire or wont crank at all
mine is the wont crank at all so going by what others have said the diesel stop solenoid isnt at fault.

The strange thing is that unplugging the ECU and plugging it back in enables me to start the car.

What i am looking for is a way to totally bypass all of the alarm ECU so that i dont ever have anymore problems with it trouble is i cant find any wiring diagram for it to know what i need to do..........

Regards Rich

Hard luck mate... as is a security system there's no diagrams freely available, easest way is to override the immo circuit, you also have another micro switch + cam for the CL. Unpluging the ecu and so removing the power supply is I think resetting it. Try by disconneting the disco battery and see what happens.
And faulty as in they break being plastic but then u need to look-see

this works on 200 dont know abou 300 but cant see why not. put switched relay fed live feed to ing. and fuel solinoid, and seperate button controled live to starter relay. also fit isolator somewere as security

Thanks for the reply,

Looks like i may have to do a bit of trial and error wiring to try and get round it. worst ways i could leave the ECU in and fit a switch on the dash to either break the live or earth to the ECU which should have the same effect as unplugging it.

Regards Rich

uncle albert said:

this works on 200 dont know abou 300 but cant see why not. put switched relay fed live feed to ing. and fuel solinoid, and seperate button controled live to starter relay. also fit isolator somewere as security

Click to expand...

Hi, thanks for the reply, i have read this a few times now, looks like this may be the best option - will have to do some more fettling when the weather perks up a bit.

Regards Rich

my .02

I had a 95 NAS D1 V8 5spd, that the previous owner had removed the alarm module, meaning that I had no central lock in the door and an immobilizer issue.

The central lock was corrected with a momentary switch wired into the harness for lock/unlock signal.
The immobilizer fix that was done, by previous owner, that left wifey stranded was a wire tap between Black & Black/orange. I later had to make it a permanent connection so that I didn't need to remove the right side kick panel every time the truck hit a bump.

Hi the connection on mine is between 2 black and orange wires. No solid black at the ecu but I have to keep the ecu plugged in for it to work then disconnect and re connect every time I want to start it. Was your ecu totally removed ?

Regards Rich.