will this wiring set up work?

[mollydog]

with my circuitry, I'm bypassing both the temp sensor and the ECU, I am making my connection on the wire coming out of the OEM's relay to the fan.

I managed to copy the wiring diagram for the Elise rad fan ( I re drew it):




hope this is further help


@ Richard, thanks for this diagram, if I don't have to switch from pos to neg, I rather not have the switch over relay

have I got this right? sorry for being a bit dumb when it comes to scemetics

 

[mollydog]

Have I got it right

like this?





is the feed from the NO (normally open) a neg feed?

 

[mollydog]

yes clydey , it look that way as I connect to the neg feeding the rad fan

 

[plugsandsparks]

@itselectric

like this?

@ mollydog I give up ! - good luck

 

[mollydog]

@plugsandsparks

I know, I really wish I could follow these instructions, thank you for trying to put me right, I really do appreciate it very much all the effort people on here are making for me

 

[Richard Burns]

I may have misunderstood the type of realy in your first modification, if so apologies.

However from the Elise rad fan diagram the supply goes from the battery, switched through the relay and then through the fan to ground.
You need to know whether the battery is supplying positive (as is standard now in many UK cars) or negative.
i.e is the Elise negative ground or positve ground.
This is critical to making this work.


Your timer relay, does it have an inbuilt momentary switch or are you adding this to the circuit?
If you are adding it, then what is it switching, the coil directly or an item on the circuit board?

 

[itselectric]

The one problem you will have is the current rating of the fan, as you need to protect the relay with a 3amp fuse you will probably need to put the red wire loop before the 3amp fuse and put a further fuse in to protect the fan. Make sure any cabling you are using is big enough to carry current.

Remember I am not an auto electrician, I am basing my reply on the fact you said the first diagram in your opening post works.
The other things to check will be the current rating of the contacts of your timer relay are big enough to switch your fan, and what would happen if the sensor pulled in when you have set the timer, you may get a backfeed to your ECU.

There are other guys on here who can guide you better

Also on some of your diagrams you are showing another relay and on other diagrams you don't show one.
If you value your car visit an auto electrician.

 

[plugsandsparks]

@plugsandsparks

I know, I really wish I could follow these instructions, thank you for trying to put me right, I really do appreciate it very much all the effort people on here are making for me

Its OK, really. I build ECUs for a hobby and rallycars for that matter as well, so its pretty easy to do what you want but that diagram keeps putting 12V onto the ECU which is bad. I understand your concern wrt leaving it on but could you not have an illuminated switch, you can certainly hear mine when its running so the chance of leaving it on and draining the battery is pretty remote. Otherwise bring your relay and switch up to Derbyshire and I do it at a weekend for free

 

[clydey]

yes agree with above
look at post 10 diagram 1 your original which works
the second diagram post 10 using the extra timer, take out the neg lead of com and bridge pos+ timer to com
the com then feeds this pos voltage through the timer contacts to n.o. when timer operates
this pos voltage then operates the original relay
has the timer got separate contacts for the momentary switch or has it a button
also as said the ecu may be sending a conflicting signal

 

[mollydog]

Once more many thanks to you all for all your help,

about me,, English wasn't my first language and the 18 months English schooling I had, I left school not even being able to read and write, so I appreciate your patience in trying to help me very much

to answer a few questions, the Lotus Elise is negative earth, and at the moment I connect to the rad fan, between the fan and the factory fitted relay, my error in not showing you this in my first diagram

knowing that the way my circuit is set up at the moment works, I was hoping I could fit this rely/timer in place of my present on/off switch

this time delay/relay is rated at 10 AMP

It has a built in momentary switch as shown in the diagram and at #2 in the diagram one can connect an extended switch which is what I will do, @#3 this is how I can set the timer with, from 3 about seconds to around 3 minutes

my understanding of electric diagrams is limited, but once I get to know what I'm to do I can follow instructions, so please don't stop every bit will be of help to me, many thanks

 

[mollydog]

@itselctic


at this moment I'm using a relay to swap over a poss fedd to a neg feed, but if my timer is sending a neg feed to the fan then I'll do away with the relay, maybe not shown in all my diagrams but the live will be fused, so if anything is wrong the fuse gets it first

 

[clydey]

ok think of it this way the original relay requires a positive feed via the momentary remote switch to
energise a coil within the relay and the relay energises. A second and totally independent set of contacts ground one side of the fan.it may appear that when the relay is not energised that this fan connection reads positive this is not actually the case it is floating to pos via the motor in the fan and feed from the real pos side and grounded negative when relay energises
when i say not actually in reality it does reach pos BUT if you put a tester on this point it could appear that the neg of the fan is changing state from pos to neg when the relay operates when in fact the floating fan is then grounded at this point

 

[Richard Burns]

What about this?
Your diagram edited.

 

[mollydog]

Thank you for your edited diagram Richard, at present I connect at point "A" also

in your edited diagram would I dispense with my relay (converting pos to neg) and connect the wire from the NO on my timer strait to the wire coming from the factory fitted relay to the fan at point "A"?

my set up in action, without a time delay though

Elise S1 fan switch - YouTube

I came across this snippet from the Elise forum from a guy who was also planing on fitting a fan override switch

+++
Ive been tinkering again

Ive thought for sometime it would be good to have a manual fan switch. Mostly for use on trackdays but im sure it will come in useful if we ever have a summer and im stuck in traffic. Ive had a nosey and this is how it works ( i think ) The fan is switched on via a relay due to the load currents. This is controlled by the MEMS ECU. The positive side of the relay coil is always live when the ignition is switched on. The ECU grounds the other side of the coil when the fan is required.
+++++


I think this is where I use a neg to ground the feed from the ECU
I'm sure this is starting to make sense to a lot of you now,

only wished I got to know more about car electrics

 

[Earthstore]

Sell it and buy a Honda....... Sorted