Fans came on with ignition this morning

[ChilliWhizz]

Damn things, turned ignition on this morning and fans fired up.... then wouldn't go off... got to where I was going and had to disconnect battery to stop fans running.. got home and same thing... so battery disconnected to stop fans and window down so I can get to door opener easily... I'm running MS2 so no otter switch.. I'm kinda assuming it might be the temp sensor (top of engine behind where dizzy used to be?)... maybe not working or connector corroded so sending ECU high temp signal even from cold.... ? Not had time today to investigate but thought I'd throw it out there in case anyone has had same problem....

Thanks fella's...

Chilli

[ChimpOnGas]

Random question I know, but is your horn working

There is logic behind this by the way

[ChilliWhizz]

ChimpOnGas said:

Random question I know, but is your horn working

There is logic behind this by the way

Hi Dave, yes mate it is, just been out and connected up battery, fans fired up... turned on ignition and horn working fine... also disconnected the (I think...must check) temp sensor top front of engine but fans still whirred alarmingly...

Weird or what....

[Sardonicus]

Edited by Sardonicus on Sunday 5th October 19:12

[ChilliWhizz]

Sardonicus said:

Edited by Sardonicus on Sunday 5th October 19:12

Thanks Simon

[ianwayne]

On mine, I'm sure the fans only run if the ignition is on (and the engine is hot of course).

If they're running without the key in, they must have been modified in operation?

Edit: note - read thread properly, I see you're running MS2.

[ChimpOnGas]

ChilliWhizz said:

Sardonicus said:

Edited by Sardonicus on Sunday 5th October 19:12

Thanks Simon

I'm with Simon

[jojackson4]

Over ride s/w??

[ChilliWhizz]

ChimpOnGas said:

ChilliWhizz said:

Sardonicus said:

Edited by Sardonicus on Sunday 5th October 19:12

Thanks Simon

I'm with Simon

Now I'm really confused

[phazed]

If the fans are on when my ignition is turned off then the fans cut, (MS2 fitted).

I suggest you have some power bleed through into the fan circuit.

The fan circuit is effectively rewired when running MS.

Just thinking,...........from memory I believe the fans run constant power and the switching is done with the earths.

So possibly an earth issue into the circuit.

Contact Shaun, (MS2Tuning) he may be around your way and sort you out.

[ChimpOnGas]

ChilliWhizz said:

ChimpOnGas said:

ChilliWhizz said:

Sardonicus said:

Edited by Sardonicus on Sunday 5th October 19:12

Thanks Simon

I'm with Simon

Now I'm really confused

Sorry Chilli, fans & horn on the same fused circuit so just checking that.

No idea what Simon was up to with his ghost post

Like Peter says, its probably an earth issue.

[rigga]

Agreed I think you have a wire down to earth.

[SILICONEKID345HP]

These things do happen when you don`t use a car

[carsy]

You`ve not been messing about with the fan settings in the MS have you Chilli. I know what you are like for tinkering now you have that new workshop.

Seriously though, as said above the fans come on by being grounded, in your case through the ecu. Somehow they are being grounded unless the settings have been altered in the ecu.

[Sardonicus]

ChilliWhizz said:

Thanks Simon

Sorry long day

[ChimpOnGas]

When my ECU relay failed on the way to Le Mans I bypassed it taking the live direct from the immobiliser, oddly this only brought the ECU to life but not the fuel pump so I added a temporary switch on the fuel pump circuit.

Turning the ignition on I could fire up the fuel pump and run it continuously using my temporary switch, then by pressing the fob I could bring the ECU to life, with both fuel pump & ECU live the car would start and I continued to Le Mans.

The odd thing was when I flicked my temporary fuel pump switch the rad fans came on, but when I pressed the immobiiser fob the fans immediately went off

Clearly the fans were taking the earth off my new fuel pump wiring, but as soon as the ECU came alive when I pressed the fob the earth circuit defaulted to the ECU, with the coolant temp was lower than I've set ECU to bring the fans on the the fans went off.

At the same time the horn failed because I'd inadvertently bypassed the horn relay by taking away it's live, I got to Le Mans & back like that, and even carried on with my "get me home hash-up" for a while after that.

My point is with an after-market ECU you really need to talk with the installer to understand how it's wired before you have any hope of tracking down your fault, to me it sounds like a relay or an ECU issue.

On the Canems system the Lloyd boys fit two relays (one for each fan) up by the rad, they are triggered by the ECU but as the ECU is effectively on a switched live when you turn the ignition off the fans go off too even if the coolant temp is over 83 degrees.

Personally I'd prefer them to cycle with the ignition off like pretty much every other car, if yours cycled with the ignition off I expect the Megasquirt ECU is on a permanent live, if that's the case check the fan output on your ECU to see whats happening.

Until you find & fix the source of the problem and if you have fan relays like my Canems, you could always pull the relays out of their holders to kill the fans when you leave the car so you don't drain the battery .

Just remember to put them back in when you go for a drive.

Good luck with it.

[ChilliWhizz]

Dave thanks for all the info.... I'll do a it more investigation this weekend...

[ChilliWhizz]

Finally got round to a bit of investigation, connected battery and No1 fan fired up immediately (ignition was off). Disconnected battery, pulled the No1 fan relay out, reconnected battery and no fan put No2 fan relay into No1 relay slot and still no fan... fired her up, got up to temperature and No1 fan cut in So, No1 fan relay at fault...

Interesting that a failed relay switches the fan on without any signal from the ECU, 'spose it lets you know immediately there's a problem rather than getting a signal from the ECU and not responding resulting in potential overheating....

Thanks for all the input chaps, now off for a bit of a hoon

[rigga]

Its just the contact stuck in the relay, could easily work the other way and the contact will never make when the relay fails.

[ChilliWhizz]

rigga said:

Its just the contact stuck in the relay, could easily work the other way and the contact will never make when the relay fails.

Ah right! Could fail either way then... You learn something new every day....