Immobiliser Problem - CIVIC '00 MB27 UK made

[CIVIC00]

Hi All! :wave:

I use my car rather seldom once a week (3000 - 5000km / year). I have random problem to unlock immobiliser with my factory key with immobiliser chip.
Details:
1.I have car-battery fully charged (VCC checked OK). - I recharge it myself every 2-3 months - alarm is always off to minimize battery discharge when I park in the garage .
2.No metal things by the keys which could prevent authorisation of key.
3. Sometimes the immobiliser doesn't want to unlock (green key blinks like wronk key/no key inside). It happened once in the garrage (I had tried about 10 times to unlock it by my usual key. After that I had tried my 2'nd new unused black key but it didn't help) I had to wait about 5 mins and after that to everything work again.
After every first successive immobiliser unlock I can't start car (starter works intensive but not ignition) - sounds like fuel pomp disabled (but I heard it worked during previous try of starting with locked immobiliser). Next I turn off and turn on the key- everything works like a charm till next occurance of problem.
4. It hapens totally random but once a several ignitions.

Is it possible that it is wrong receiver circuit in car or something wrong with connections/communication with other parts of ECU(keys are not suspected 1 unused and 1 used behaved the same way)? Is there any Electric datasheet to my car model here?
Where to find connections/plugs which could be involved in communication between immobilised components(Any passive components to replace on key - Authentication PCB) . Is it possible to fix the receiver and where to localize it? I suppose it is near the ignition keylock but how to recognize it?

Any help welcomed. I am Qualified Electronic Engineer/Designer and I can check replace myself anything (even on PCB) but I have to know where to find it. :D

[ECU-MAN]

Hi mate

to me sounds like its your IMMO reciver, this is the bit that goes around the ignition lock.




http://b16a2.kicks-ass.net/pics/immo.jpg



if you look at the pic above, all the immobiliser components are there

1= PGMFI ECU
2= Immobiliser Control Unit
3= Red Key
4= Black yey
5= Grey Key ( vallett mode ) Prelude, Ledgend, Oddessy, NSX
6= Reciver
7= Immo PCB from inside the ECU

the reciver ( 6 ) poweres the transponder in the key and reads the value of the key ( 4 ) , it then passes that to the Immo control unit ( 2 ), the Immo Control unit has a password programmed into it by the Honda PGMFI tester, or the honda HDS. this password is matched to the ECU ( 1 ) as well. I have read on the net someware that this password, well data is stored in a serial EEPROM in the ecu, commonly a 93CXX on the main pcb of the ECU.

In normal conditions, you turn the key, the code is read from the black key to the immo control unit, the immo control unit validates the key, then sends a signal to the pgmfi ecu. this signal is uniq to the immo control unit and ecu, you cannot change ecu's in these cars ( with out programming ) as this signal will not be valid and the ecu will not allow the car to start.

good luck.

[CIVIC00]

FIRST Thank You Very much for Your technical reply!

I am considering one thing:
Do You know if the Receiver part (6) is powered directly from regular battery VCC=12V or is it powered from any supplemental VCC made in the Immobiliser Control Unit(2)? If Receiver part (6) is powered from inside the board(2), maybe some Capacitors powering it are bad, or suplemental VCC for the chip which reads the key is bad - not stable?

Do You have any pic or datasheet of the ICU board(2)?
Do You know if the signal from receiver goes directly to the "decoding key chip" or any additional receiver circuit is on board (2)? Or maybe there is additional receiver circuit in Receiver part(6)?

I ask You becouse the dealer works in standard procedure - replace everything until problem go away or even more:(
They don't care - customer pay.
I wish not to be a sponsor of replacing everything including coding the keys in the new ICU if it is any small thing to replace - maybe only Receiver Part(6).

[ECU-MAN]

Hi

I have no data sheets for the Immo Controll unit ( 2 ), but it does poweer the reciver ( 6 ). I dont know the operating voltage, but it will be filted and regulated in the Immo control unit. if you want I can measure it on my delsol and put the Ociliscope on it to see what come's out.
Ill take a Pic for you of the Immo Control unit PCB both sides. ( later on tonight ) CBF now.

[CIVIC00]

Superb!!

I am waiting for waveforms and pics. It will be very helpful.

Best Regards.