mk2 punto sporting, replaced engine now wont start

[davidol]

Hi guys, as above really, ive got a 2000 W registered mk2 fiat punto 1.2 16v sporting with the 6 speed box and the engine expired on me (overheated) so ive replaced the engine and reused the orginal ECU, however it now wont start, the starter motor doesnt even attempt to kick in and the CODE light stays illuminated when the key returns to its position after attempting to start. Im guessing its an immobiliser fault but ive no idea where to go from here, Ive got 2 blue keys for the car, one equipped with a central locking button and the other without.

I did a bit of seaching and somewhere somebody mentioned the the crank angle sensor needs to be re-used from the orginal engine as its paired to the ECU but i cant see this myself, can anyone confirm or deny that?

HELP!!

 

[arc]

Hiya.

The crank angle sensor is not coded to the ECU.

The immobliser does not stop the starter motor from turning (it works by not allowing power to the fuel pump/coils/injectors etc).

I'd suggest checking your wiring, something is off somewhere. I don't know the punto loom to well - but a common mistake when working with centos is to forget to plug in the main power for the engine wiring loom as it is a seperate plug than the main engine -> body loom connection.

 

[davidol]

Thanks for the info, is this cast iron? One probable mistake i may of made thinking about it now is ive left the earth wire that connects the battery's negative terminal to the gearbox however i'd assume the engine would earth to the chassis through the mountings somewhere along the line, will check this and report back

With regards to the loom for the engine it came pre-installed on the donor engine and i just had to plug in the 3 multiplugs that go into the fusebox on the right side of the engine bay, so everything there is as fiat intended, if thats the case then and the immobiliser is allowing power to the coil/fuel pump etc should i be able to bump start the car?

 

[davidol]

ok quick update reconnected the earth wire to the gearbox after checking conntinuity between the rocker cover and the negative terminal which was showing no connection, checked again and now have continutiy but no difference, code light is still illuminated and wont even turn over, any ideas?

 

[arc]

Thanks for the info, is this cast iron? One probable mistake i may of made thinking about it now is ive left the earth wire that connects the battery's negative terminal to the gearbox however i'd assume the engine would earth to the chassis through the mountings somewhere along the line, will check this and report back

With regards to the loom for the engine it came pre-installed on the donor engine and i just had to plug in the 3 multiplugs that go into the fusebox on the right side of the engine bay, so everything there is as fiat intended, if thats the case then and the immobiliser is allowing power to the coil/fuel pump etc should i be able to bump start the car?

That earth is vital, engine mounts are suspended in rubber and don't tend to earth all that well. Without it connected then it is possible that the current has attempted to earth else where and done some damage.

The starter motor and alternator should have their own thick red cables that link them, and then run to the main +ve terminal. They won't (as far as i know) be part of any multiplug.

I'm not 100% on the punto wiring, but am pretty sure the ECU cannot prevent the starter from turning - indicating you have at least two faults. The lack of starter, and the code light being on.

As i say, i don't know the punto OE wiring that well - but have fitted a stilo engine into a cinqucento using a megasquirt ECU.. so have had plenty of fun diagnosing issues and the like.

 

[davidol]

your correct in saying the starter motor and alternator have there own direct connections to the battery, these are in place, as well as the multiplug being reconnected. As above ive checked the continunity from the rocker cover to the negative terminal and everythings fine there so im stumped, a mecanic mate is popping over on wednesday to do a diagnostic scan for me so im hoping that'll shed some lights on things

 

[davidol]

UPDATE!!!!

Just a quick update as this may be of some help to someone in the future, i checked the voltage between the rocker cover and the positive terminal to check for any flutuations whilst cracking and there were none which suggested all was well but i also checked the continuity of the earthing bolt on the ECU and the negative terminal and there was nothing.

Ran a temporary earth connection from the bolt to the negative terminal and the CODE light went out and it cranked and started first time, so although the earth wires are connected check them with a multimeter for continuity!

 

[arc]

good to hear it's resolved!