fan overide switch 350i wedge

[Mica350i]

New member here (Billy no mates apparently!)
New to wedge ownership too and getting her ship shape for the summer if it arrives. I am looking at the Steve Heath diagram for the Overide switch and am I right in thinking this is a complete change from the existing wiring? Mine has a permanant earth to the fan and the live is switchable via the relay from the thermo switch on Rad? Steve Heath bible seems to be the other way around.
Thought I'd ask the experts before I do some damage !
I'm no emechanic but wanted to get into the spirit of Wedge ownership and try a bit of DIY !
or is there any info from old discusions (couldn't find any)
Paul

[adam quantrill]

It probably depends on who installed it.

You can either wire the switch across the fan relay if it can take the current, or across the 'otter' or thermostat switch.

I also put in a bulb to indicate the fan was going, which was useful.

[ed_crouch]

Usually pin 85 on the relay is earthed via the otter switch in the rad: when the coolant temp reaches the right value, the otter switch closes, earthing pin 85, energising the control solenoid and activating the fan.

If you wire up a parallel path between pin 85 and earth, with a toggle/rocker switch in it, you have a way of overriding the otter.

Of course, if the engine is way hot and you happen the switch the fan off, the otter switch will still provide the necessary earth to keep the fan running as it will also be closed.

Bonzer.

Ed.
P.S. Pins 85 and 86 can be wired either way, so if 85 is wired live, then 86 will be earthed via the otter, or vice versa. A few relays have a diode in them to stop people wiring them in reverse. Truth is it doesnt matter which way you wire it: 85 - 86 is just a small solenoid.

[Mica350i]

cheers fellas
the electrical schematics make more sense now
I should have said the fan is not working either ! I have shorted the otter and the relay 'clicks' but no live feed is going to the fan. Is this usually something common (bad conection, faulty solinoid, etc) and where is the solinoid ?
Paul

[adam quantrill]

Fuse?

The relay is the last part of the chain.

[Mica350i]

cheers Adam
just checked it and the relay was faulty.
£7 for a new one and I'm up and running.
who says TVR's are a pain .......... although did knock the lights out (diode) while refitting it ! oops !
bybass switch will have to be another day quite while I'm ahead.
thanks again