S2 cooling fan

[mac]

Looking for a bit of help here before I do anything rash.

The cooling fan on the S2 has stopped working, I've checked the fuse and it's fine, I've swapped out the relay for the horn one, and the horn still works and I've replaced the black sensor as detailed in the service manual.

Is it my fan that's knackered - is there anyway to test it using a direct connection?

Anything else I should be checking etc?

I did notice that very little fluid came out of the sensor port when I replaced it, could it be that it's sitting in a wee air pocket and that's why it's not working?



Mac

[tut]

Mac

If it is the same as the S1, they can just pack up. However on my cars they partly seized after not being necessary for months.

I could get at the fan blades with a long screwdriver through the front grill on mine, and spin them to free them up, but not sure about an S2.

tut

[robin]

Mac,

On th e S2 the stack temperature display derives from the same temperature sensor as the ECU uses; so if the stack displays the correct temperature then the ECU knows what temperature it is.

It's very simple to check the circuit but you'll want a multimeter and some methodical testing. If you haven't used the multimeter before, make sure you know how to measure both resistance and voltage with it before working on the car - voltage can be tested by measuring a little AA battery or similar source; resistance can be tested by touching the probes together - should read <1 ohm; when the probes aren't touching anything you should see a symbol (often "OL" or just "L") meaning out-of-range, i.e. the resistance is near infinite.

Remove the relay. Look at the underside - each terminal has a number next to it - those numbers should be:

30
85
86
87

Possibly there will also be 87a.

Now work out which of these terminal blades fits into which slot on the relay socket (you'll need to imagine rotating the relay and sticking it in the socket; track the position of each terminal through the rotation).

With the relay still removed, take a length of wire and connect socket terminal 30 to pin 87.

If the fan spins you have a fault on either socket terminal 86 or 85. 86 should measure the same voltage as socket terminal 30. If it does then you have a break in the loom between 85 and the ECU. If it doesn't then you have a break in the loom between 86 and 30 (i.e. right under the relay socket).

If the fan doesn't spin when shorting 30&87:

Find a suitable electrical earth.

Use a multimeter to measure the voltage between earth and socket terminal 30 - it should be > +12v whether or not the ignition is on.

If it's zero then double check fuse 12. It should be >+12 on both sides at all times. If the fuse is OK, but socket terminal 30 is

If it's some inbetweeny voltage you have a very weird problem - more on that if it happens.

If it 's >+12 then use the multimeter in resistance measuring mode and measure the resistance from pin 87 to ground is <100 ohms or so.

If the result is infinite resistance (open circuit) then you either have a wiring fault from the relay socket to the fan, or the fan has burnt it's windings and gone open circuit.

If the result is a low-ish resistance (greater than a few ohms) then the fan motor is probably OK, but the blade is trapped, or the motor is seized.

If the result is near zero then the fan has gone short circuit and the fuse 12 should blow every time the fan is operated.

Let us know what you find out.

Cheers,
Robin

[tut]

Mac

If my method does not work, then try Robins..........



tut

[mac]

Tut,

Your method was next on my list - but thought I should post up incase that didn't work


Robin,

Thanks - comprehensive and written in plain english as always. I'm hoping that something works - otherwise I'll be spending most of tonight flapping newspapers at the radiator when Mandy come into the pits.

Her other suggestion to prevent the car overheating in the pit lane was to stay out for the full session

Mac

[mac]

Tut, you shouldn't sell yourself so short.

I connected up the pins as suggested by Robin and could hear that it wanted to turn. disconnected, gave the fan a turn with a screwdriver and hey presto!


Mac

[tut]

Jolly good Mac.

"A" levels failed, but learnt a little bit about Elises over nine years.

tut