Transmitter lead connection ?

[mrdoiron]

Umm...I might be wrong, but I suspect that you may be misunderstanding how your original system was supposed to work. Forgive me if I'm the one that's misunderstanding whether or not you are misunderstanding but...

It should be wired so that 12 volts goes into one end of the switch that is mounted on the choke cable. When you pull the choke cable the switch closes, sending the electricity out the other end of the choke cable switch and down the line to the water temp switch, where the electricity will stop because that switch is open when the engine is cold. Once the engine warms up, the water temp switch will close, allowing the electricity to complete the path to ground. Once that path is complete, the electricity will flow, illuminating the cold start lamp.

The top part of the picture is the way it should be, the way I described above. Below that is what you have--Specifically, the temp switch is out of the circuit completely and the other side of the choke switch is wired to ground. This way, all you need to do is pull the choke out, closing the choke switch, completing the path to ground, illuminating your cold start lamp. Whew!!

Agreed here... this is what I tried to explain as my understanding, this answer and the next are clearer however... so I need to connect to the water temp lead to the switch near the firewall behind the dash...however is there a fuse in-line prior (between 46 & 59 on your diagram) ? Today I assume the choke cable switch is just going to ground instead to the water temp switch as your bottom diagram shows - just need to make it back home to validate this on Friday...

thanks again, great help guys - mike

[109 Pretender]

My 67 109 has this 'do-hickey' as well. It's a wax bulb that is supposed to open the gnd connection to your choke lamp after the engine warms up enough to not need a choke to run. Light goes out and then you manually turn off choke. This is an early attempt at what I call H/W level 'plug and play'. You see, after our education system began failing - instead of trying to educate people on how to use the technology in their lives, engineers decided to design around our now faulty minds. Been going downhill in this direction ever since - hence the 'automatic choke'...

It appears your mech wired the lamp directly to gnd. And that's ok too. YOU just have to remember to turn off choke when engine starts chugging black smoke out and runs rough after it's warmed up.

IIRC that part is not cheap and they usually are bad.

Cheers!

[jac04]

It's a wax bulb that is supposed to open the gnd connection to your choke lamp after the engine warms up enough to not need a choke to run. Light goes out and then you manually turn off choke.

No. The water temp switch closes the connection to ground when the engine warms up. The light comes on, then you manually turn off the choke.
See SafeAirOne's post for the correct information.

[SafeAirOne]

No. The water temp switch closes the connection to ground when the engine warms up. The light comes on, then you manually turn off the choke.
See SafeAirOne's post for the correct information.

PLEASE NOTE: I didn't consider the possibility of the temp switch working the other way round when I made the diagram. I don't have a choke, let alone a water temp switch, so don't rely on my theory of operation of the temp switch to be factual. I will say with enormous certainty that the wiring diagram is correct, though.

I will admit that I hope my theory of operation is correct, because I can't go back and edit my lenghty response anymore...

[jac04]

...I hope my theory of operation is correct...

It is.

[Sputnicker]

By the way, a lot of old British cars used this switch, which is commonly referred to as an "Otter" switch. Be sure you get the "normally open" version, which shorts ("closes") when hot.

[mrdoiron]

By the way, a lot of old British cars used this switch, which is commonly referred to as an "Otter" switch. Be sure you get the "normally open" version, which shorts ("closes") when hot.

So what is there today seems original ... so it should be correct and close/short when hot.

thanks gents, mike