No obvious ECU damage but suspect immobiliser/wiring problem.
Car fails to turn starter on occasion but has also been started with the transmitter ring disconnected from the wiring loom.
I have not encountered an ECU/immobiliser problem on a MK2.5 car where the starter motor does not turn. This does not mean it is not possible, just that I have not stumbled across it until now.
Is it possible for any problem with a MK2.5 ecu/immobiliser/transponder to stop the feed to the solenoid and suppress the starter?
Faulty ignition electrical connection.The white contactor on back of lock.?? We have assortment of ecu,s if you do need one.Not sure on the starter not turning but the mk2.5 has alarm also built in so maybe its run through that? Power up the starter directly ,in nuetral of coures, and see if it fires up. As you know the ecu can cause all sorts of issues .I have had sveral here with wide range if issues from non starting to ,non charging( even though the alternator light was not showing),No spark, no fuel, but most common is immobiliser issues ,some with key light showing some no light showing.I have not failed yet to get them sorted one way or another.
I have sold dozens of ECU sets to cure the common problems but this is new to me.
Most sets are required because of a water logged ECU that has failed. The transponder and immobiliser work fine bit there is no communication with the ECU, so no fuel and spark.
Familiar with the white plastic contact block on the ignition. These do fail and this is where I would expect a problem with the starter motor to originate as ignition contacts feed live to the small wire on the solenoid that activates the starter motor.
I know you have these cars in for breaking. Please can you do a test for me. See if the starter motor will spin with the immobiliser and/or transmitter ring on ignition disconnected.
I am not worried about the car actually firing up - just whether unplugging the immobiliser box from the loom and/or the transmitter ring from the loom can somehow stop the starter spinning.
In my opinion there should be no effect but customers car says otherwise.
I think that the later immobiliser systems do inhibit starter motor operation, it’s to prevent them being able to be driven onto the back of a truck using the starter motor. I’ll double check on the wiring diagram, what’s the car’s VIN? I’m not sure how it would have started with the pickup coil disconnected though!
By any chance was there another key taped to the reader/aerial ,that fell out possibly.I have seen a few cars with different coded key sellotaped to reader itself and not on the actual ignition lock
I have several cars here ,some are Jdm, but Uk spec cars all turn the starter with immobiliser disconnected incl 2 x mk2.5 but 1.6 models.2001 year approx.
Looking at the wiring diagrams (UK) for the facelift NB, they all have a starter cut relay which is controlled via the immobiliser unit. The starter cut relay is not used on pre-facelift NB. I seem to recall that the starter cut relay comes into play after a certain number (3 maybe) of failed attempts at starting, for example repeated use of a non coded key.
Thanks for getting back to me on this guys - appreciated. My ECU kit has been posted back to me, so should arrive today. The friend/breaker I bought it off got back from Le Mans and called me yesterday. He has a similar car with the same ECU so I will post whole kit up to him for testing.
Thanks for checking the cars Rob. If they are 2001, would be MK2.5 facelift cars.
Robbie - the car is a late MK2.5 1.6, UK car. It is fitted with the B6NB ECU so will likely be around 2004 vintage.
Customer was plugging in his existing immobiliser alternately with mine. With mine plugged in the starter would not turn. With his plugged in the starter would turn and the car fired and ran for a while without the transmitter ring plugged in - bizarre! Even if there were a hidden key, the ring should need to be plugged in to the loom.
As you say Robbie it wouldn’t take many starter turns in gear to get a stolen car onto a trailer, so this may be why there is a possibility that it has been immobiliser controlled in some later cars. I guess a disabling of the starter when car in gear and no security handshake would have been too complicated.
Weird stuff and new knowledge apart I am facing the fact that after more than 2 years of supplying these ECU kits, one of them is quite possibly faulty:-(
Sold my Mini Cooper last night so will have to buy a MK2.5 to play around with.