Tazio Posted January 3, 2015 Share Posted January 3, 2015 As I don't have a heater, and as I want to install a manual override switch for my radiator fan, I was thinking of utilising the heater fan switch to perform the function. Problem is the diagrams I have are not clear which a re the actual switched contacts I can use for this. Anyone give me a clue? Alan Link to comment Share on other sites More sharing options...
Member Jonathan Kay Posted January 3, 2015 Member Share Posted January 3, 2015 There's a diagram in the archives which shows how to do this with a diode to enable you to keep the built-in switching. Have a search and tell us if you can't find it.Do you want an indicator on the dash as well?(There's also a get-you-home tale which isn't the one you want.) But why do you want to do this: what's the advantage over the usual set-up?Jonathan Link to comment Share on other sites More sharing options...
F355GTS Posted January 3, 2015 Share Posted January 3, 2015 IIRC the fan has an ignition switched live directly conencted, the earth to complete the circuit is via the Radiator temp switch.I did exactly as you plan on my last 7 and just ran an earth to the In terminal on the heater switch then from the out terminal a wire to the out terminal of the Rad temp switch. Link to comment Share on other sites More sharing options...
Tazio Posted January 3, 2015 Author Share Posted January 3, 2015 JonathanThe new ECU is controlling the radiator fan, via a relay, in the event of relay failure I want to be able to switch the fan on manually.I'll use the Search function but don't hold out much hope. Link to comment Share on other sites More sharing options...
Tazio Posted January 3, 2015 Author Share Posted January 3, 2015 F355GTSThanks for that.YHM. Alan Link to comment Share on other sites More sharing options...
Member Jonathan Kay Posted January 3, 2015 Member Share Posted January 3, 2015 I'll use the Search function but don't hold out much hope.It's not too hard to find the thread, but the link to the diagram is U/S. I've activated a back channel...But if it's only for emergencies I'd carry a jump wire or the components thereof and apply it when needed.Jonathan Link to comment Share on other sites More sharing options...
Mavic82 Posted January 3, 2015 Share Posted January 3, 2015 Alan,assuming you you will not be using the loom connections, just the switch perhaps it would be possible to check continuity across pins with a DVM. I think I have a spare in the garage so will give it a go later.cheersGuy Link to comment Share on other sites More sharing options...
Tazio Posted January 3, 2015 Author Share Posted January 3, 2015 Guy,You are right, I don't intend to use the original loom connections, just the switch rather than fit a simple toggle switch.Alan Link to comment Share on other sites More sharing options...
Mavic82 Posted January 3, 2015 Share Posted January 3, 2015 Alan,i have ohm'd out the switch and confirmed with the wiring diag.in the standard car, pin 3 is live and switches pin 2 for low speed fan (through a resistor) on the first on position and switches fan full speed through pin 1 at the second on position. the side small Lucar connections power the switch tail tail.cheersGuy Link to comment Share on other sites More sharing options...
Tazio Posted January 3, 2015 Author Share Posted January 3, 2015 Cheers Guy, much appreciated, and for the diagrams too.Alan Link to comment Share on other sites More sharing options...
Member Jonathan Kay Posted January 4, 2015 Member Share Posted January 4, 2015 Thanks to help from another member I now have the circuit diagram for the override switch, as printed in Low Flying in 2004 and discussed here. And as soon as I started typing this I remember that it might already be here... and it is.But there might be another thread that questions one of the relay terminals... Jonathan Link to comment Share on other sites More sharing options...
Paul Deslandes Posted January 4, 2015 Share Posted January 4, 2015 Well done JK. One word of caution with that diagram, and this refers to the thread of a year or so ago when Glasgow was having problems, if you happened to use a relay with an internal diode, it will be the wrong way around as marked, and relay pins 85 and 86 should be reversed.Otherwise, job's a good 'un!Paul Link to comment Share on other sites More sharing options...
Member Jonathan Kay Posted January 4, 2015 Member Share Posted January 4, 2015 That's the bit I was trying to remember (and find)!Jonathan Link to comment Share on other sites More sharing options...
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