Technical engine management light on

[jsolesbury]

hi everyone. some advice would be great
i got a 2001 1.2 brava 80 sx. car has given me no problems at all until a couple of weeks ago when the rad fan would not come on. i changed the temp sensor and the relay but it still does not come on. (the fan was replaced only 2 months ago and works when wired direct to the battery). the temp gauge appears to work correctly.
now the engine management light is permanently on. the car is very difficult to start, almost as if the ignition is too advanced. (turns over ok but wont fire up)
anyone got any suggestions? presumably it needs a diagnostic??
thanks

 

[mountainmachine]

Yup you should (might) have an OBD port in your fuse box so if you find someone with an OBD reader you could get them to do it for you. I got one of eBay works well.

 

[jsolesbury]

would this do the job?

http://cgi.ebay.co.uk/OBD-OBDII-OBD...ameZWDVWQQrdZ1QQcmdZViewItem#ebayphotohosting

would it work with a standard laptop? and would it tell me exactly what the problem is?

dont know much about ecus and car electrics im afraid!!

 

[mountainmachine]

No that would work if you didnt have an obd port and not as well. First things first open your fuse box and check for an obd socket. the one on the right of the steering wheel.

If you have one your best bet is to get a handheld scanner, if you check i'll find you one once i know you def need one. Expect to pay between £35-50 for one. possibly more or less if you want one to connect you a laptop.

 

[jsolesbury]

had a dianostic this morning and the ecu is buggered! giving faulty readings. any suggestions on repairing it or does it need a new one?
thanks mate

 

[mountainmachine]

Well what did the garage say? Did they say they couldnt read any codes off it, it does sound like you may need a new ecu, or a 2nd hand one off a scrapper of the same engine and model. With it being a 2001 i wouldnt know if you could use any younger models as they may not have an OBD interface, i think yours would be a CF3 revision. I'd need the vin no to check (pm if you want, dont post)

 

[jug]

had a dianostic this morning and the ecu is buggered!

did a fiat dealer say that, or a back steet monkey with a 3rd party reader who used the wrong socket

 

[mountainmachine]

You mean you dont use the cigarette lighter?

 

[jsolesbury]

a local engine tuning company did it. there were recommended and the guy seemed to know what he was doing!!
he could not turn the rad fan on and the ecu would not give a coolant temp above 79 degrees when it clearly got well above that.
now the ignition is well too far advanced and its running really rich so there must be a sensor on the ignition somewhere?? what does the sensor on the top of the engine do? (camshaft sensor?) and i presume the phase sensor is the sensor on top of the cambelt cover?
cheers guys. its giving me a right headache now!

 

[jug]

sounds like coolant temp sensor needs replacing.
on this model the coolant temp sensor is actually 2 sensors built into one. this means the temp gauge can work fine even when the ECU is getting no signal.

when you say he couldnt turn the rad fan on, do you mean he tried to earth it directly and it would not switch on (suggesting fan fault)? or do you mean it would not switch on by itself when engine was hot (suggesting coolant temp sensor fault)?

advanced ignition and running rich sound like its running in cold mode all the time, possibly due to a faulty air temp sensor (not uncommon on 1.2 models).

the sensor on top of the engine that you're talking about sounds like the knock sensor. this is working fine judging by your symptoms.

the ignition is mainly adjusted on the basis of the signal from the crankshaft position sensor (aka RPM or TDC sensor) which reads notches on the flywheel. if overfueling is also a problem it suggest this sensor is fine, plus you'd have other problems if this sensor was faulty.

according to my manual there is no camshaft position sensor (aka phase sensor) on this model, which seems weird

 

[jsolesbury]

i replaced the coolant temp sensor but problem remained.
i have had the ecu tested by bosch (who made it) and they say its knackered.
any ideas where i can get a replacement? fiat want 309 for an exchange unit or 700 for a new one. seems steep!!
thanks

 

[mountainmachine]

scrapyard, you'll need various other bits to go along with it as well.

 

[jsolesbury]

what else do i need? immobiliser and key?

 

[jug]

you need:
-ecu from a 1.2
-matching codebox
-matching red key chip for that codebox


an ecu is pared to a single codebox. if you stick a used ecu on your car, it will not pair with the codebox in your car, meaning the immob remains on. if you get a matching codebox but dont have the red key (at least the chip from insude the key), you cant teach the codebox your blue key codes. your red key wont work with the new codebox, only the original red key for that codebox will.

you need all 3 matching parts from a donor car. often these cost £100.

programming your blue key codes into the new codebox is easy if you have the red key for that codebox. it takes 2 mins and is something you can do yourself (procedure is on many previous threads if you search)

worst case scenario, if you cant get the red key to match the codebox, at least get a blue key that works on the donor car, then you take the chip out of that key and swap it with the chip in one of your blue keys, then the car will work, but you wont have a red key.

the other option is to get an ecu decoded. then the immob is disabled and you can stick that ecu in any car and any key will start the car, even an unchipped one. reddy4bed can do this for you if you PM him.

 

[jsolesbury]

hi guys
i ve ended up buying an exchange ecu from fiat. expensive but worth it i thought! BUT my cooling fan still doesnt come on AND now instead of it running too rich, i have ZERO throttle response!
i took the new ecu back to bosch and they have tested it and said it is 100% ok.
engine mang light is not on
any ideas gratefully received!!!
thanks guys

 

[jug]

the fan issue is due to a fault, the possiblities are endless so some testing is needed. the fan should constantly have a live, it is negatively swtiched, so first things first test it has a live and that it works when earthed directly.

the throttle response is possibly going to mean a trip to the dealer to have the throttle position relearn procedure carried out, although it may improve once the ecu has had a good chance to learn on its own.

 

[jsolesbury]

the fan does have a perm live and the negative when wired direct to the battery works fine. temp gauge works fine also.
may the throtle prob correct itself in time then? run the engine on idle regularly then??
thanks

 

[jug]

drive it daily, if it doesnt improve within a few days it means a trip to the dealer is needed

the next stage of testing the fan problem is the relays. there are 2 relays the high speed and low speed. both are situated on the front side of the battery tray. it is not uncommon for damp and dirt to get on them, causing bad connections, corrosion, and relay failure. disconnect both relays and check the connectors are clean and rust free. squirt some wd40 on just in case. now check if the fan comes on once the temp gauge gets up past half way (can take a good 20+ mins at idle even this time of year).

 

[jsolesbury]

the throttle problem goes away when the cooling fan circuit error is cleared from the ecu. limphome mode or something?

so im left with the fan circuit causing all these problems!
the fan works when wired direct to the battery. It has a perm live (which has been tested and is ok). the temp sensor was changed and the dash gauge works fine. the relay has been changed as well (all dealer parts). only got 1 relay tho. would other be for air con (which i dont have fitted)?
otherwise it must be the wiring?:bang:

thanks for your help

 

[jug]

you're right, on non-A/C models you would only have the single relay (i assumed it had A/C).

since we know that the relay is fine the next thing to check is that the relay has a good earth. there are only 4 wires connected to the relay. one if the live from the fan, one is the earth to switch the fan on, and the other two are for the switching circuit, both connected directly to the ecu. you need to determine if the problem is to do with the fan's earth or the switching circuit.

if the relay's earth tests fine you know the problem is to do with the ecu not switching the fan on.