Thread: Cold Start Warning Light 74 109

Originally Posted by Dark61

....
I'm still intrigued as to what the Thermostat is all about.
cheers,
D

The 'thermostat' referred to is a thermal switch that comes on when the cylinder head temperature reaches operating temperature, so the choke light only comes on when the knob is pulled out and the engine is hot. The thermal switch (545010) is triangular and located on top of the head next to the thermostat housing, held by three screws. It was not fitted to all Series 3, although the parts book gives no end date.

John

Interesting again John and thanks. I'll have a look and see if I can see any sign of the thermostat ever having been in situ. Blimey ! They don't want you to have a working choke light on this model - part 545010 I GBP69.56!
cheers,
D

Originally Posted by Dark61

Interesting again John and thanks. I'll have a look and see if I can see any sign of the thermostat ever having been in situ. Blimey ! They don't want you to have a working choke light on this model - part 545010 I GBP69.56!
cheers,
D

That switch has solid gold wiring, diamond bearings and can only be assembled by highly trained spider monkeys, hence the price. Hopefully you'll be able to coerce a cheap copy made using copper bits and assembled by humans to work

If I have to pay that sort of money for it I'll end up wearing it!


Turned the choke cable over and found these three holes. I guess this is where the switch sits. The pin on the middle of the switch is sprung. I'm unsure whether it completes the circuit when its in or out. Out with the multimeter and the long leads tomorrow.
cheers,
D
p.s no sign of the thermostat ever having been fitted

When you pull the choke out the switch should become closed, but there is no earth until the thermo switch on the head closes at 55C or whatever.

So the circuit is live to switch with ign on, and earth to thermo switch.

Regards Philip A

Thanks Philip.


I've seen two circuit diagrams for this . One showing both the thermostat and the switch, the other, just showing the switch. So I guess I have just the switch version - no sign of a thermostat ever having been fitted.
cheers,
D