Another Immobilizer problem

[bassmanSteve]

Hi guys. I'm new to this forum so please be kind.
I'm Steve from Cornwall UK and have just bought a 2011 Piaggio xevo 400ie in a private sale.
This is another "no master key" and dodgy immobilizer question and I have searched previous posts but haven't found anyone with the same symptoms as I have.

So, I didn't know about the master key thing and bought the bike with just one blue key. The bike was starting OK and I drove it home.
This is what is happened next ......

Came to the bike the following morning and noticed a coolant leak coming from the thermostat. Fortunately the guy I bought it off had given me a spare engine so replaced the leaking one with the one off the old engine.
Started it up to bleed the air out. Turned it off and then it wouldn't start again.

So, I switch ignition to on, hold brake lever, turn kill switch to run and the immobilizer light briefly goes off then pulses very fast so almost a solid light.
The bike cranks but won't start.

Here is the strange bit. Came to it the next morning and it starts straight away. Went for a quick ride and switched off at home, tried to start it again and same thing, very fast pulsing light, cranks but no starting.
It seems that if I leave it for a few hours it starts straight away but won't re start after that.
I am hoping that one of you experts can give me a clue as to what it might be and what I can do about it. I have already asked for my money back but the guy seems to think it might just be the antenna at fault.

[Dave Milnes]

From the manual:-
The immobiliser system is tested each time the ignition-key switch is turned from OFF to ON. During this diagnosis phase a number of control unit statuses
can be seen and various light codes displayed.
Regardless of the code transmitted, if at the end of the diagnosis the led remains off permanently, the ignition is enabled. If, however, the
led remains on permanently, it means the ignition is inhibited:

1. New decoder - key inserted: a single 2 second
flash is displayed, after which the LED remains off
permanently. The keys can be stored to memory,
the vehicle can be started but with a limitation imposed
on the number of revs.

2. New decoder - transponder missing or illegible:
The LED is permanently ON; in this condition,
no operations are possible, including starting of
the vehicle.

3. Decoder programmed - service key inserted
(normal operating condition): a single 0.7-second
flash is displayed, after which the LED remains
off steadily. The engine can be started.

4. Decoder programmed - master key inserted:
a 0.7-sec flash is displayed followed by the
LED remaining off for 2 sec. and then by short
0.46-sec flashes the same number of times as
there are keys stored in the memory including the
Master key. When the diagnosis has been completed,
the LED remains permanently OFF. The
engine can be started.

5. Decoder programmed - fault detected: a light code is displayed according to the fault detected,
after which the LED remains on steadily. The engine cannot be started. The codes that can be transmitted
are:
· 1-flash code
· 2-flash code
· 3-flash code

Diagnostic code - 1 flash
A one-flash code indicates a system where the serial
line is not present or is not detected. Check the
Immobilizer aerial wiring and change it if necessary.

Diagnostic code - 2 flashes
A 2-flash code indicates a system where the decoder
does not recognise the transponder signal.
This might depend on the inefficiency of the immobiliser
aerial or the transponder.
Turn the switch to ON using several keys: if the
code is repeated even with the Master key, check
the aerial wiring and change it if necessary. Otherwise
replace the faulty key and/or reprogram the
decoder. If the problem persists, replace the decoder.

Diagnostic code - 3 flashes
The 3-flash code indicates a system where the decoder
does not recognise the key. Turn the switch
to ON using several keys: If the error code is repeated
even with the Master key, replace the decoder.
If this is not the case, reprogram the
decoder.

The intermittent nature of your problem sounds more like a loose connection, bad earth or poor fuse connection. Look at everything you disturbed during the parts swap. Also there is info on here for a place you can send the ECU to that will bypass the immobiliser so the lack of a master key is not an issue.
Check all the fuses for dirty blades and if you download the manual make sure there aren't any 'hidden' fuses that control things like the ECU, decoder etc.