immobiliser central locking not working help??

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pratchy

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Hi i`ve got a P reg 300tdi, been sat for a couple of weeks battery flat, took battery off charged it and replaced it. now the immobilser led on dash does not come on, central locking does not work and engine will not start. Have replaced battery on key fob (2 button) Engine turns over but will not fire.
Anyone know what the cause of this is?? The immobilser and central locking worked fine before battery went flat.
 
I have read alot of posts on similar problems some which have the exact same symptoms, and after checking fuses and connections i am no further forward. Does anyone know what could be affecting the alam/immobiliser and central locking? I also seem to be without heated rear window and rear fog lights???:(
 
If you can crank the engine then it's not immobilised, so you will have to look elsewere for the reasion of the engine not starting.
I don't know what vehicle u have but if it a disco the multifunction unit controls the two items also wiper delays, interior lights and lights on and key in the ign. switch beeper.
 
It is a discovery and evrything you have mentioned controlled by the multifunction unit is playing up. Will have a look at it on the morrow. Many thanks
 
May be the MFU supply fuse has poped. The MFU is on the rear of ther fuse board.
 

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I have rechecked all fuses and they are all intact. The multifunction unit is working intermittently (interior light fade not working, rear wiper worked then stopped, no rear fog lamps, no heated screen, key in ignition sounder worked then stopped) I found a test procedure for the MFU but could not get it to enter diagnostic mode. Is there another component that could be affecting the MFU (relay or something??) and where would i find it? or do i need to replace the MFU? other symptoms still persist (no alarm, no c/locking, no led on dash) Turning over but No fuel getting to injectors.
 
There's not much you can do with an MFU that's failed only to check that it's pluged in fully, the alarm has an input to the mfu, and as I don't understand the mfu function fully it maybe that having a faulty ecu will have some bearing on the alarm etc not working.

I had a faulty ECU last january and I couldn't enter the diagnostic mode didn't nitice it affecting the CL though. Fitted a new MFU and all is back to normal.
 
Bit of an update. I went to the scrappy today and found myself a MFU and fuse board. Fitted the newly aquired MFU and most of the electrical faults i had i.e (interior light fade, rear wiper, key in ignition sounder, etc) cleared up but still no central locking on key or on fob, no alarm, no immobilser led on dash. Engine turns over and diesel is getting to the injection pump but not to the injectors. I also found a kilo of acorns inside my heater blower motor and some sort of what looks like rodent **** on a few of the wires down in the passenger footwell. Judging from the amount of acorns and empty nut shells in the engine bay i suspect whatever has been eating these has been there for a while. I can`t see any visable damage to any wiring although i can`t see all the wiring. Can anyone suggest anything other than me removing the dash to solve my "problems"??
 
took the dash out the other day to inspect the wiring loom and to my surprise and dissapointment could not see any damage to the wiring. Have borrowed an old multimeter from a friend and have tested a few things. I am a complete novice in the arena of autoelectrics but have nevertheless managed to confirm that my battery is reading 12v all the fuses in the engine bay fusebox are reading 12v. I have also tested all of the yellow relays i could find inside i think 8 and the 2 green ones, these all seem to be working. I have also tested the multiplugs that the relays fit and all seem ok except 1 located behind the passenger footwell side trim panel which shows nothing either side ie 85 / 86 but does give 12v on 87 which seems strange to me. lastly i have tried to check the multiplugs that feed/return from the alarm ecu AMR 6429 i don`t really know what i`m looking for but i could only detect a live on 1 of the wires in the multiplugs. Does anyone know whether this would be right? or if there should be more than one wire live to the alarm ecu? Would be very grateful for any help at this stage.
 
Also checking main fuse board today one of the fuse terminals on fuse5 satellite 1 reads 12v and with the fuse removed i get 5v on the other side??? These readings are with the ignition switched on. Ideas??? Anyone??
 
ok a little progress. I sourced a second hand alarm ecu amr 6429 with key phob plugged it in and hey presto i now have central locking/ alarm and immobiliser working. But still the engine will not fire, still not getting diesel through the fuel pipes to the injectors.
I thought that if the alarm ecu was faulty it would explain the diesel not coming through the injection pump as part of the immobilser process, but now having replaced the alarm ecu and having the immobilser function properly i can see that had it been immobilsed it would not have turned the engine over or let diesel through the pump.
so with the alarm off and vehicle not immobilsed the engine is turning over but no diesel at injectors.
Am i looking at two seperate faults occuring simultaneously?? Injector pump and alarm ecu?? or am i indeed going mad??
Any and all suggestions greatfully recieved!!!:doh:
Also heated rear window now works with new alarm ecu???
 
Last edited:
Finally got her running today!!!
Removed the black plastic box on the end of the fuel injection pump, dispensed with the three wires and the little micro chip in silicone covering the stop solenoid. Ran a live from the battery to the stop solenoid on injection pump via a very neat switch on the dash and whey hey off she went. Mega chuffed!!!
Still struggling to understand what caused the multifunction unit, alarm ecu AND the black box on the injection pump to fail at the same time, but fail they did. ANYONE???
Anyhow thought i would post my findings as i do love a thread with a happy ending.;)
 
might have gotten a few more replies in the discovery thread. this ones more to do with specific engine faults, tho i see the logic of posting here with your problem initially.
glad you sorted it, was informative to follow. only just seen it as i dont look in 300 engine thread too oft!
 
It was ignorance that led me to post this here, in fact its ignorance that leads me to do most things. I wondered why i didn`t recieve an awful lot of help with this. I thought the gods were maybe calling for me to go it alone.
Next time i will post in the discovery forum!!!
 
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