Technical Fiat Punto 2003, Engine Coolant Failure

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Technical Fiat Punto 2003, Engine Coolant Failure

matt20687

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Hello,

I have got a 2003 1.2 fiat punto. I have got a annoying problem, it all started with the engine fan blew and stoped working and therefore overheated a few times, the person who had a look at it bridged the fuse and thermostat plug to see if it was the fan that was nakered, the fan poured out with smoke and since then the engine diagnosis light has come on and the heat gauge has stopped working and the engine fan only turns off once you turn the car off not when the car is getting too hot.

I have had the car plugged up to read the fault and it came back with 'engine coolant circuit failure'.

Course this isn't much bloody help as i pretty much knew that anyway. I have replaced the thermo transmitter and it work fine and was so happy, went out bout 3 hours later to give it a proper test run and the bloody thing stopped working again and went back to the same problem.

I have now got a new job and only drive my car once or maybe twice a week when previous i was driving it every day. My cd player has a constant feed and so the display is constantly on as i always forget to take the front off. Could this drain the battery or do you think my problem with the engine coolant circuit part of the problem ?

If anyone can help please please i will be so grateful.

Many Thanks,
Matt
 
Thats the thing, the original problem is the engine coolant circuit, but were do you start.

Any chance it would have short a cable out or the next closest thing down the line as the fuse was blown and then my uncle bridged it out so therefore had no way of shutting the power off when a fault occured?

Thanks,
Matt
 
If the fan fuse had blown, it's probably because the fan has, or has begun, to seize. Bridging the fuse is a stupid thing to do as the fan would draw a huge current while trying to turn, hence the smoke. If it hasn't melted the wiring and the engine-bay fusebox you can count yourself lucky. Fit a new fan and kick your Uncle in the crotch.

An "engine coolant circuit" fault suggests an issue with the coolant temp sender or its wiring, not the fan (fan is ECU controlled via the coolant temp signal, not by a fan switch like the mk1). A failure of the coolant temp sensor, or an open circuit in it's wiring, will put the ECU into Limp Mode with a 'default' temp reading and the cooling fan running constantly. If some numpty has bridged the temp sensor connector, he's probably damaged or opened-up the terminals and caused a poor connection, which is probably why it worked intermittantly. Repair the connector and it'll probably work ok.

Radio/flat battery won't affect the cooling system.
 
ah right ok, i know the engine fuse box is ok because i have checked it and the internals aswell and checked that the correct voltage etc was coming in and out of the terminals.

I a currently trying to find a wiring diagram for my car so i can see what goes were as i can only trace it back so far.

Anyone have any clues for links ?

What would be the next part after the thermo transmitter? Would it also be possible if a relay has blown and is stuck in the position to say the engine is to hot and the fan needs to come on ??

This is great, gives me something to go by, so any info is great.

Many Thanks,
Matt
 
oh and i forgot to mention, i have replaced the fan and it works fine, just doesnt turn off until bout 3 mins after you turn the car off

Thanks,
Matt
 
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normal for cooling fan to run for a few mins after engine switch off; is the fan cutting in and out as it should when car is stationary and up to operating temperature?
 
normal for cooling fan to run for a few mins after engine switch off; is the fan cutting in and out as it should when car is stationary and up to operating temperature?

No, the fan turns on as soon as the car has been started and does not turn off at all at any point until after a few minutes after the car has been turned off. I was thinking last night, as the heat gauge doesnt work either, could the ecu think there is a major problem (e.g the car is overheating) and tell the fan to stay on constantly?

We have looked over and over and over again and it doesnt make sense, just wondering if we arent looking in the right direction.

Thanks,
Matt
 
i have replaced the thermal transmitter. Thats for the heat gauge isnt it?
Is there anything else that would affect the heat gauge?

Thanks,
Matt
 
Hello,

I have bought the haynes manual for my car. Mainly for the wiring diagram for the engine coolant system as i seem to have a fault on it.

I dont seem to understand where the heat gauge comes in as from what i can make out is:

Starts at the battery then feeds a 30A maxi fuse, this then goes to the relay which then goes off to the fan (which has a neutral straight from the neutral off of the battery).

I have two questions:

1) Where does the heat gauge come into this (does it work through the ECU? If so how?)

2) On the engine cooling fan wiring diagram their is a line coming off of the relay that is marked engine management (does this mean the ECU?)

Thanks,
Matt
 
The coolant sensor tells the ECU what is going on and the ECU triggers the switching side of the relay.

AFAIK there is only one sensor on an MPI, built into the manifold, but I could be wrong.

Cheers

SPD

Right ok, so what are the chances that the ECU is shagged? On the diagnosis it said engine coolant circuit failure, is this just the wires or will it count the ECU aswell??

Does anyone have any ideas what i can do, or even to look at??

Thanks,
Matt
 
Really the only ways are to take it to an ECU doctor and they will test it, or to someone with the full Examiner system who can do it on car.

Cheers

SPD

Right, any ideas on how much this will cost?

Could i get the program and lead for my laptop ? would that work?
 
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