Emerald Fan Wiring - How Do You Have It?

[Dream Weaver 2]

Just finishing off the last bits of the car for tomorrow's MOT but I need to sort the fan out. I know its not needed for the MOT, but dont want it boiling over whilst there.

 

I've ditched the std wiring setup, and just have the fan wired into a relay, then into the Emerald.

 

Fan is wired to pin 87 of relay, power goes to pins 30 and 85 straight from the pos distribution box through a 15A fuse, and the switched earth from the Emerald goes to pin 86.

 

However, it doesnt work

 

I've set the Emerald to switch the fans on at various temps to test the system and it never switches on even at low temps.

 

Any ideas? I could swap 85/86 round so the Emerald is switching pin 85 but I didnt think this made any difference as it just switches the relay coil?

 

I also want to put an override switch into the dash to switch on manually - would the following work:

 

 

Oh, and tested the fan jumped straight to the battery and it turns on its own with no problems

[Craigb 2]

Have you checked that pin 6 is actually going to earth when the temperature events occur .

[Wurzel 16]

Only thing I can suggest is the contacts on relay (85 and 86) be swapped over. The coil maybe trying to operate in the wrong direction.

 

I guess the ecu is providing the earth path rather than a power supply (safer) so you need to ensure that this path is being provided at your desired temp. The old multimeter is required here or a simple battery with bulb affair.

 

Other than that, I reckon your circuit will work assuming you use the correct type switch

Edited May 17, 2006 by Wurzel

[Dream Weaver 2]

Craig - Emerald provides switched earth so earth's the relay coil, hence switching the power to the fan.

 

I'll swap the relay connections and check them first, then add the switch.

 

Wurzel - what type of toggle switch can be used? I have a 3 way tiny switch here, but it is AC and has 6A at 125vAC written on it. I used it in my old MR2 to control the level of the pop up headlights and it worked fine but not sure if its the right switch to use.

[Craigb 2]

Craig - Emerald provides switched earth so earth's the relay coil, hence switching the power to the fan.

 

Understand that it is a switched earth , all i was saying is by checking that it is switching to earth when required , then one failure mode is eliminated...

 

[Wurzel 16]

A switch is a switch really, you just need to make sure that the earth path is switched correctly from through the ECU or to your seperate earth on the chassis somewhere and that you can wire it in so that only one path is earthed at a time. Again, a multimeter will tell you what is going on. The connection to the relay coil must be common to both obviously.

 

Like you say though, get the system running without the switch first and then go from there. It shouldn't take too long to sort out as the circuit is pretty simple

Edited May 17, 2006 by Wurzel

[tom_m 0]

i think your best bet for the overide switch would be to have it completly separate to the ecu/relay circuit, just piggy back it with dual connectors. that rules out having the wrong type of switch that stops your circuit working.

 

and i'm afraid your circuit diagram makes no sense to me whatsoever so i can't help there. the relay is just a switch so when connected both the ecu side (switching) and the fan side (switched) need both positive and earth. i can't tell from your diagram whether this is true or not.

Edited May 17, 2006 by tom_m

[Rob_the_Sparky 10]

Personally I'd disconnect the Emerald until you can make the fan work through the relay. Once you know the relay is wired up correctly then connect up the ECU.

 

If the Emerald switches to earth then your over-ride switch will work fine as drawn. It also would be a good way of testing the relay...

 

Rob

 

P.S. The ECU is expensive, hence make sure the fan and relay are OK before connecting it up. Last thing you want to do is damage the ECU, have blown enough things up at work to know how unforgiving electronics are.

 

P.P.S. Given that you are only switching a tiny current (the relay coil) then you don't have to worry much about switch rating. If you were switching the fan directly though it would be a very different ball game.

[Dream Weaver 2]

Thanks Rob, as I thought with the switch, and good idea to get the fan working separately from the ECU first of all

[Wurzel 16]

And this will be the last electrical query I'll answer

[Dream Weaver 2]

Whys that then?

 

Anyway, thanks for the help everyone - spent a couple of hours rewiring the relay last night, and adding the switch and all is fine now

 

Just need to test the ECU switches it on when the switch is in the ECU mode.