Hi everyone, I wonder if you might be able to give me a hand in getting my cooling fan going. I need to use the car for a long journey and still can't fix this fan.

It has has a new fan (works brilliantly if lead to fan switch has connectors bridged), new fuses, checked relay, new fan switch, new single pin sensor, new temp sensor (inlet manifold) and I have reset the ECU by disconnecting battery. It still won't come on!!!

I did get it to come on by wiggling the fan switch plug once but I have checked that lead and it's not at all corroded or loose (bridge always works perfectly). That's why I changed the switch.

Now the new single pin earthing sensor on the top of the block makes the temp light come on and actually start dim and get brighter as the car gets hotter. What the hell else is there to do? All wiring must work because of bridging and also the fact that the light is consistently brightening (off when cold). The temp light does not come on with ign.

Many thanks,
Sam

crossstc said:

sensor on the top of the block makes the temp light come on and actually start dim and get brighter as the car gets hotter

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Should not do this. You have a sensor fitted instead of a switch.


With regard to the fan issue, you have to check you have 12v at the thermo-switch connector. Then a continuity test to the fan connector and finally to earth. Basically a continuity check through the wires. You can bleed the radiator to see if you have air locking which would cause the switch to not read correctly. This happens when head gasket is gone.

Take the rad fan sensor out and heat it. Boiling water whatever. Does it work then?

Is that SPI or MPI engine?


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Yes I have tested the fan switch in boiling water and nothing happens. The single pin sensor on top of the block is the right one and just starts dim and gets brighter as tbe engine gets hotter. Fairly sure there's no air in tbe system.

crossstc said:

Yes I have tested the fan switch in boiling water and nothing happens. The single pin sensor on top of the block is the right one and just starts dim and gets brighter as tbe engine gets hotter. Fairly sure there's no air in tbe system.

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As mentioned it sounds like the single pin sensor you have in the head is actually the sender unit for a Cinq. They look identical and locate in the same place.

I had the same issue on my Sei.

Yes that makes real sense as a sender unit would behave like that. Touching the earth that is that single pin wire to the block brings on the light. For that reason and the bridging, I suspect it is all good wiring wise. I know the fan switch works, it's brand new and the second one too as I originally thought maybe the new one I got was a dud. So what is left for it? Thanks again people.

Sorry to sneak on this thread but I am having an issue with my new cylinder head - and Duncans comment seems to ring a chord.

My engine temp light is coming on (not fully bright but visible) but the engine is not overheating (fan still goes on and off - rocker cover is very warm (not painfully hot) to the touch.

It looks like they fitted a new temp sensor when the reconned the head.

How to I tell a Cinq from a Sei one - and would this cause this problem ?

I work for a motor factors and we use a parts lookup system called Autocat. From what I can remember most of the brands listed on Autocat had the incorrect part listed for Seicentos. Autocat is a very common system through the aftermarket parts trade so very likely that garages/factors supplying wrong one without knowing.

Is there any way to tell the difference (markings colours etc) ?

Sensor gives resistance reading. Switch should be open circuit.

DRSIK said:

Is there any way to tell the difference (markings colours etc) ?

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Think the Sei switch should have grey top to it.