80 Electric Choke Operation Question

[jz7p6t]

I believe the wiring diagram in the '80 service manual for the Electric Choke is incorrect. It shows the Electric Choke Control Relay Coil being controlled by a bulb in the cluster. I figure it must actually be something that indicates the engine is running like an oil pressure switch or signal off the sender. Does anyone know what does control the Electric Choke Control Relay?
Thanks

 

[Enigma]

I found this explanation somewhere before. Maybe it will help.

When the ignition switch is turned on, voltage is supplied through the warning light to the choke heater. Under this condition, the light is illuminated and the high resistance in this bulb provides a very low current flow to the choke heater so the choke spring is not heated if the driver leaves the ignition switch on with a cold engine. With the ignition switch on, current also flows from the ignition switch through the relay winding and the alternator field to ground. This current flow keeps the relay contacts open.
Once the engine starts, the alternator supplies approximately 14 V to the entire electrical system. Under this condition, 14 V is supplied to both ends of the relay winding, and the current flow through the winding is stopped. Since this relay is normally closed, the contacts move to the closed position and supply full voltage to the choke heater to open the choke. When the choke relay contacts are closed, equal voltage is supplied to both sides of the choke warning light, and this light remains off. If a defect occurs in the system, such as a defective relay, current flows through the warning light and the choke heater to ground. This light is illuminated to inform the driver that a defect is present in the choke heater circuit.

Enigma

 

[jz7p6t]

Manual missing important information

It is true that in the Ign Run position with the Engine NOT running, the Electric Choke Telltale will be On. Reason is that the Electric Choke Control Relay is Energized (Contacts are now pulled OPEN) and NOT supplying Power from Battery to the Electric Choke Directly. However, once the Engine IS Running, the Electric Choke Control Relay is Not Energized (Contacts now CLOSED) and supplies Battery Power to the Electric Choke.
This operation does prevent the Electric Choke from heating up and opening when the engine is not running.
The problem is that the 1980 Corvette Shop Manual does not show what circuit is energizing/deenergizing the Electric Choke Control Relay. I assume it is either an oil pressure switch or a circuit derived from the oil pressure sender circuit.
Luckily what was wrong with my 1980 was a bad connection at the Electric Choke. I replace the wiring terminal and cleaned the choke terminal and everything works fine. But I'd still like to know what is controlling the Electric Choke Relay.

 

[Enigma]

I see your point. I believe that the square zig-zag item should actually be shown as a normally closed contact and then the above explanation should apply.

Enigma

 

[jz7p6t]

Yeah, that's another thing wrong with the circuit diagram in the manual. And until I actually took the Choke Relay apart, I thought it was some type of "flasher" relay that cycled on/off. It's a simple on/off relay but circuit operates backwards from what you'd think, Electric Choke is energized when Choke Relay is Not. It seems to be working ok but now I have to rebuild the carb.