While tearing into the car today I came across this. It's marked 12v 40A so that's easy enough and under that is '400'. One end goes to the power lead on the horn relay on the fender and the other as you can see goes to what looks like the fuse panel backside. This is located just below the wiper motor on my 66 Cutlass.

 

I believe that's a fusible link. It's not on my 67, and I don't have a 66 wiring diagram. It may be specific to a convertible.

 

It's a cct. breaker. Another style will fit into the fuse receptacle in place of the regular fuses.

 

I'm not familiar with the intricacies of the '66s, but I think that's an aftermarket unit.

The circuit breakers were generally used for the power window and top circuits.

- Eric

 

I don't think it's aftermarket.
My vert has the same one, same place.

I will check my CSM and see if I can find it.
Although, mine has two orange wires attached that
come out of the firewall.

 

Page 12-18, shows a pic and calls
it a circuit breaker.
Page 12-56 at the bottom shows it to
be the breaker for electric seats, windows
and or convertible top motors.
This would explain why mine has the 2 wires.
Convertible top with a power seat.
Hope this helps Trip.

 

That makes a lot of sense Adam. Is there a mechanism inside it that would make it act as a circuit breaker and resettable or is that just another name they used for it to function as a fuse?

 

Yes that does help a lot, thanks all. Since I don't have power seats or windows I was leaning toward it being the circuit breaker for the convertible top. 40A is pretty big.
Now since I don't have the convertible top motor (don't ask me why, that's prior owner asshatery) I'll have to check it and see if it's good. Do you think just doing a continuity check across the poles is sufficient to test it?

 

Yes.

 

That's exactly what it is. It is self-resetting. There's a bimetallic spring inside the circuit breaker. If there's a short or overload, the spring heats up, opening the contacts. Once it cools, the contacts close again. It's just an on/off "switch" so continuity testing works fine.

 

...Or just replace it. NAPA has bins of them.

cb 1.jpgcb 2.pngcb 3.jpg

 

None of which look anything like the factory one in the original post.

 

Well you have had a little time to think about it. Care to revise your trite response?

 

I don't think it's bad I was just curious. Just seemed like an odd spot for a circuit breaker. It is factory from what I can tell. It just has that funky plastic piece attached to the screw posts, almost like a cradle for the wires. It does look like the NAPA ones in the pic from Coldwar if you were to take the plastic cradle off. Why the factory choose to use the cradle is another question.
It seems the previous owner bypassed the original switch and had a on off toggle on the underside of the dash. I'm not sure how that worked because the original switch is a dual pole, yes? (3 contact)
In due time I'll have all the answer as I continue on.