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New relay didn't fix the problem. Now when i turn it on in the morning the fans don't come on but after a few minutes they start up. They don't switch off at all until i take the key out. One of the relays is still switching on and off rapidly and very randomly but it happens so fast that i can't find out which one is doing it. Looks like i have got to have a go with the multimeter after all.

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Just one more thing. The fan relay is Not change over type !

it should be 5-blade double make&break (when the relay is on

then 87 and 87b is +12v out )

One more thing I noticed :

When I check the el. diagram there are 3 wires connected to the Fan relay

position 86 or 85 (wire color Black/orange) one from A/C, Fan fail teale and

the Fan control relay.

if your Rad fan control relay(or ECU error) you can evt.

removed the 2A fuse from fusebox(front) top ->right side) this fuse

used only connected to the Rad fan control relay, so if you just remove it and if fan stop then you have a problem with the Rad fan control relay in engine room or ECU or temp sender !

Edited by esp88
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I also suggest you can check with the Freescan (in canse you have problem with ECU or sensor)

I forgot tell you, the fuse box has 24 fuses and only 2 fuse has 2A, So, I think

it's easy to find !

when you remove the 2A fuse but if not stop the fan then you have a prolbem with A/C request. In this case you can check by removed the 7.5A (center colum and no. 3 from top) fuse !

Good luck !

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Jut checked the fan relay in the front box and it is the right one after all. Pulling the 2Amp fuse does stop the fans so i checked the fan control relay in the boot and there is battery voltage on pin 85 coming straight from the ecu. Guess that means either the ecu is at fault,wiring or the temp sensor. I don't suppose you have the pinout diagram for the ecu by any chance so i can check that?

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The EUC connector Green(J3) E8 (cable green/purple). you can see from my first attached pfd file!

but removed the 2A fuse not stop the fan means more like you have problem with 2 other cables connected to fan replay (A/C)

The 85 may commning from fuse no. 21 +12v it's OK I think and when ECU

on then pin e8 to ground !

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Just had another check on the 85 pin of the fan control relay in the boot (green and purple wire)

With the ignition off (ecu off) pin 85 goes to ground via the ecu and the fans do not turn

With the ignition on (ecu on) pin 85 has 0.12 volts going through and the fans work

Pulling the 2A fuse DOES stop the fans

Every now and then the fan control relay switches on and off rapidly which causes the fans to stop and start but i can't work out why its doing this.

Edited by davegtst
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Had another check and it seems the ecu is switching the fans on constantly. Pin 85 of the fan control relay is a negative switch controlled by the ecu and the fault seems to be with this wire or the ecu or the temp sensor as it is switching to ground as soon as the ecu is switched on.

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I seem to be getting nowhere with this, now they don't work at all unless i put the aircon on full. There is good continuity between pin 85 and the ecu so i guess its narrowed down to either the ecu temp sensor or the ecu itself. 2 good things came out of todays work though, i did the ram air mod and sorted out the uneven idle by disconecting the throttle jack.

Anyone know where the ecu temp sensor is? I found the gauge one easily enough but the ecu one seems quite well hidden.

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  • 4 weeks later...

Still stumped by this one although i haven't have much chance to find out what is causing it. From what i can work out the ecu is switching the fan relay (in boot) on and off randomly. If i disconect the temp sensor under the plenum the engine note changes and it puts on the check engine light so i know that works. My only thought now is the fan circuit in th ecu is playing up so maybe i have to send it away and get it tested. Does anyone know a good place to send it or does anyone have one i could swap to test this?

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  • 6 months later...

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