'78 Coupe Deville electric choke problem and Carb rebuild

[threnc]

Hey Guys, my electric choke does not work and doesn't even seem to be getting power with multimeter test.  Am I doing this right I'm somewhat of a nugget when it comes to electrical stuff? I put the red lead of the multimeter on the plug end of the choke wire and the black end to ground. It reads 0 with the key on and when cranking and when running. Does anyone know where it gets its power from and where the ground is for this? Are there any other tests I can do to troubleshoot the choke? I'm about to rebuild the carburetor but want to get the choke working first. Also, any carb rebuilding tips would be greatly appreciated. Thanks in advance, Chris

[R Schroeder]

Hi Chris,
I answered your email on this.
Check your box.
If you have any other questions, send me an email directly.
rschroeder100@wi.rr.com
Thanks
Roy

[TJ Hopland]

Even if the choke coil was bad you should have seen voltage with your test.

The ground is just trough the housing to the body of the carb and eventually to the engine which should be grounded to the chassis and battery.  There is a little metal tab on the inside of the choke heater that makes the contact to the body.

I don't recall working on the circuit specifically in a 78 Cad but GM's typical design of the electric choke era was to feed the power through the oil pressure switch.  They usually had 3 terminals, one was the usual to ground if pressure dropped for the light.  The other two close when pressure is up, this is where the feed to the choke coil comes from.   I think the power comes from either a choke or gauge fuse. 

Again this is typical GM and from memory, not specific to a 78 Cad. 

[R Schroeder]

That's pretty much what I sent him TJ.
The only thing I added was to check and see if someone added a gasket between the choke and the carb. This would kill the ground.
Roy


I also would ad that he should buy the 78 repair manual . They are all over Ebay.
This would help a lot in rebuilding the carb.

[R Schroeder]

I will ad one more thing.
A quick check to see if the fuse is blown, is to turn your key switch to on position. If the oil pressure light comes on, the fuse is good. If the light is out , I would check your fuses.
The oil pressure switch also supplies power to the trans kick down switch. If your car isn't down shifting, the oil pressure switch could be bad, after you check all the other items mentioned.
Roy

[threnc]

Thank you both Roy and TJ for your replies. It's a nice day today in the Northeast (high of 50) so I plan to get out there. I'll let you guys know how it turns out.
Thanks again,
Chris

[threnc]

Hey Guys,
Ok, I've got power to the choke thermostat but no choke activation. I tried the wire from the oil pressure switch (which is now 12V engine running) and direct from the + side of the battery. I'm thinking either it's dead or there's a gasket in there between the choke and the housing like you guys said. I'm planning to remove the carburetor for a rebuild so I'll just replace the choke thermostat at that time.
At least I know there's power to it!
Thanks again for your help,
Chris T.