3 replies to this topic

[Murrayf]

I have a small problem with a Mini Sprite

It doesn't start - the immobiliser has done its job too well and refuses to unimmobilise it. The ECU has been reset by the previous owner, but then every time the battery is disconnected, the ECU/keyfob forgets the code and refuses to play ball. The only way he managed to get the car to work was to tow it to the local Roverman and reset it.

The Car is a 1995 Sprite with Lucas alarm/immobiliser and MEMS ECU (I assume its factory fitted). The key fob is the two button type (no central locking)

I've tried the Emergency access code route (Key ON/OFF 10times, wait 30secs after alarm for LED to blink, then turn key ON/OFF according to the PIN) but the LED never blinks - so I don't have the chance to enter a PIN.

I can't see any other connection on the ECU to input the PIN in any other way (I've heard rumours of shorting various pins - but no details).

I've not tried resetting the keyfob route (tho that is only really a temp solution - I'd like a more solid solution)

I'm tempted to replace the whole fuel ECU/injection system with a carb (but then was reminded that post 93 cars will need to meet stricter emissions standards)

The other option is to swap the ECU/immobiliser with an older ECU with no immobiliser.

Clues:

The horn goes off for 30 seconds, during which time the fuel pump kicks into life for a few seconds, then all goes quiet.

After the alarm has gone off (with ignition still ON) if I fiddle the wires round the back of the ECU, sometimes a small motor spins for a second or two - sounds like its coming from the fuel injector. this might point to a faulty ECU?


Any more hints/tips welcome. I admit I'm a mini novice, so feel free to ask obvious questions.

[Dev]

You can by pass the ECU imobiliser, but i cant remember how i did it. i know it has something to do with a grey wire but my memory fails me at this present moment.

Sorry.

[Murrayf]

A little epilogue, fortunately it's good news all the way!

I was investigating going down the route of swapping the ECU with another, reconditioned (so

as not to need the code from the immobiliser). I was warned this would cause more problems

that it would solve as the ECU is specific to each model/engine size, date, etc.

I spoke to a man in Birmingham (contact details by request) who came round, reset the ECU

(by plugging in his own debugger/computer) and resync'd the keyfob back to the immobiliser.

It seems the problem I had was that the car had had the battery disconnected (or died) with

the alarm ON (ie set). It is virtually impossible to recover from this position (without the

clever computer to reset it).

If you want to remove the battery from any type of immobiliser system, it is imperative that

the alarm is NOT SET. Upon reconnecting the battery, press the ARM button at least four

times to resynchronise the handset to the car.

It is also pretty much impossible to remove a factory fitted immobiliser from such a car, as

they have a rolling code. The immobiliser gives a code to the ECU each time it starts and

vice versa, so they cannot live apart.

...then the next problem arose - to which he also quickly solved, but I'll include as an

aide to anyone else with similar problems. A simple problem that the engine span, but didnt

kick into life. After checking the sparks were ok (lie each plug out of the engine on the

block, then start the engine), and even checking the fuel wasn't having an effect (it had

been sat there for 3+ yrs - he poured new fuel direct into the air inlet). He then noticed

that the alternator was stuck, and the engine was having real difficulty trying to turn it -

in fact it was just spinning the fan belt, melting it. After cutting the fan belt the

enginer kicked into life.

Now I have a small shopping list to get the car back to a more acceptable state of repair as

it's been sat outside for over 3years. I think I'll start with a new fan belt and

alternator.... watch this space.

[Sprocket]

Out of interest what is the MNE number of your ECU. I have a 95 sprite without alarm imobiliser.

The way round the imobiliser is to fit a non coded ECU and a router box in place of the alarm ECU, you can then bin the alarm ecu, finding the right ecu and router box is the tricky bit. There are two imobilising points on cars fitted with a factory alarm, the first is the starter relay is grounded through the alarm ECU, so when the alarm is on the starter will not turn over. The second point is the coded signal sent to the engine ECU when the alarm is off. This is why alarm and engine ECUs are a matched pair. This code can be reset in the engine or alarm ECU but then you need a special chap with the apropriate gear to do it, it can get expensive.

Im sure however that this was simply a matter of re synchronising the fob with the alarm. Leaving the alarm on and going on holiday for two weeks or more, you will find the battery flat when you return home.