Fan relay wiring practice - is this ok?

[philwaters]

I'm driving my fan via a relay from the ECU (Emerald), which is grounding a pin (switched earth), so I've got a permanant 12v supply to the relay and the earth pin is connected to the ECU.

I also have a dash mounted switch to override the fan on - for pulling up in a traffic jam I can see will take a while, etc. If I just connect this to the earth pin on the relay and then the other side of the switch goes to the chassis ground it will have the same effect.

 

My question is if it is ok for the ECU for this to happen?

 

Phil Waters

[I.Mupferit]

Emerald 🤔

 

That is the arrangement I had on my old car with the Emerald Phil.

 

Brent

 

2.3 DURATEC SV Reassuringly Expensive

R 417.39 😬

 

Edited by - Brent Chiswick on 26 Jul 2006 16:54:02

[Colin Mill]

Probably - but it would be worth checking with Emerald that the output from the ECU is an open collector output or a switched ground via relay contacts (i.e. the pin won't source current, only sink it). Failing that you could do a belt and braces job and put a suitable diode between the relay ground end and the ECU pin. The would prevent a conflict between your switch (wired direct to the relay low side) and the ECU pin if it were to try to source current.

 

The phone call has to be the easy option!

 

Colin

[philwaters]

Thanks Colin - I had thought of a diode, but forgotton about it again - too much late night thinking and not enough sleep

I will give them a call, as you say it is the easiest option, I was just wondering how others had wired an override fan switch with an Emerald.

 

Brent.. yes indeed - see you tonight?

 

Phil Waters

[philwaters]

the woman from Emerald - she say Yeah, no problems, the ECU doesn't care if I ground the pin via my switch. So if anyone else reads this thread....

 

Phil Waters