Hi all ,could someone tell me how I can put a manual switch on my hisser (choke) it comes on but doesn’t always come off, this is what I’ve tried there is two wires going to the hisser and one on the otter switch, I am using a dummy switch so I can wire it up in the engine bay just for now, I left the wire on the otter switch and disconnected the two wires from the hisser,one is live I tried to put one wire from the switch to that and tried to Earth the other wire on the switch but it doesn’t work what is the best way to do it please.
Regards
Nick
I kept the feed from the coil to the hisser and ran a lead back to under the dash,where I installed a toggle switch, which goes to earth.
My switch is similar, but 3-position (a headlight style pull switch labeled CHOKE). Full in it disconnects the hisser (choke off); full out it goes to earth as described (choke on). In the middle position, it goes back to the Otter switch so that the factory wiring is intact (automatic choke). That position serves well if the Otter switch happens to be working, but you can bypass it if it won’t close when cold (pull out) or if it won’t open when hot (push in). It also provides motivation to eventually fix the Otter switch. 
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Ok thanks guys, so leave as is then run a wire from the otter switch to a toggle switch with one side to earth?
Nick
Have you tried jut quickly switching the ign off and on?
I used this technique when my ‘S’ was running, worked every time. Much simpler that running wires and keeps things stock.
Robin I was using that little trick but it’s now sticking back on for some reason,but thank anyway
Nick
Bother! Sounds like it might have a faulty otter switch then. Time to repair it?
Ok Robin I will look into that thx
Nick
It’s not just a convenience issue,
The problem is you have active current going into a device with petrol.the solenoid is now old and if the insulation fails it can short, which just opens the starting carburettor and introduced more petrol… a better way is to have a switch to isolate the starting carb before the current gets to it!so it can be turned off once started.
There have been numerous Jags burnt from this. The road test pics of the 1st MKIV delivered to Bryson’s show the inside of the bonnet already scorched on a new car.
Thanks Ed I wired up a dummy rig and it works great,thanks for everyone’s advise.
Nick
Following on to Ed’s observation of the Mark IV;
Here is what happens to the underside of the bonnet when you get a backfire and fuel spouts out through the starting carb.
This new early steel OTS did not have the anti-blow-back valve in the starting pipe connection under the intake manifold. Pushrod cars also did not have it. It was added beginning with engine W.2449 and all Mark VIIs. The same thing can happen on later cars with the valve if it becomes stuck open with old gummy fuel residue. Clean it. The solenoid does not prevent this.