cold start warning light

I was reading a previous thread that somebody asked about the otter switch fitted on the cylinder head. Have I missed something why did the cold start have an otter switch and also a switch on the choke pull , why not just one switch on the choke pull .


Well-Known Member
The otter switch is used to let the drive know that the engine has reached temperature and can put the choke off.

Some cars have an normally open switch others normally closed so the light will go on or off as the swtich makes or breaks connection.

Rover warning ights come on when warm rather than off when warm, (if my memory serves me well).
I think it makes perfect sense, the circuit is designed to warn you that the choke is on when it shouldn't be. The opposite situation is communicated by the engine not running well.



Staff member
Makes sense to me TBH. Dash warning light comes on to alert you that the choke is still on but the engine is now warm.


Well-Known Member
Hi, It also acts as a warning light when you hang your handbag on the choke knob.:)

Makes perfect sense. The otter switch senses when the engine is warm enough to not need the choke. The cable switch is to sense that the choke is still pulled out. You don’t want the light going on when the choke is pushed in so you need both switches.