1940 Sedan Circuit Breaker

mike42

mike42

Well-known member
The weather was a pleasant 35º today in Northern Michigan so I decided to put in new tail light wiring. I asked me Wife to step on brake pedal and the lights work just great except.....she said the dash lights went on when she pressed on the pedal. I checked my work and it's ok, as I put in the wires in the same as I took them out.

This car was rewired in the past and I'm thinking that someone mis-wired it then and hooked to the dash lights by mistake. In the Summer I did notice a flicker on the dash when applying the brakes but never thought much about it.

I looked over the wiring diagram and it shows a circuit breaker. Where is that breaker located in the '40 Standard ?

Thx....Mike
 
Mike, the circuit breaker is located above the steering column, high up on the inside firewall. All light circuits are served by the breaker, and no other syastem should come from this source. Not having a wiring diagram in front of me, I can't visualize where the cross-up might be, sorry.
 
Mike, follow the wires. The breaker is the metal box. The other circuit on the same mount is the ignition resistor. Nothing else electrical is mounted on the firewall.

I'm not really sure why you need to see the breaker, though, it shouldn't really enter into the problem you stated.
 
Alan .....I just want to see if any wires are attached to it. I have the wiring diagram. Also like to learn something new I guess ! The guy I bought it from rewired it he said many years ago and he really can't remember anything at all about it. I'm looking for a picture online of breaker.

Thx
 
mike42 said:
The weather was a pleasant 35º today in Northern Michigan so I decided to put in new tail light wiring. I asked me Wife to step on brake pedal and the lights work just great except.....she said the dash lights went on when she pressed on the pedal. I checked my work and it's ok, as I put in the wires in the same as I took them out.

This car was rewired in the past and I'm thinking that someone mis-wired it then and hooked to the dash lights by mistake. In the Summer I did notice a flicker on the dash when applying the brakes but never thought much about it.

I looked over the wiring diagram and it shows a circuit breaker. Where is that breaker located in the '40 Standard ?

Thx....Mike
Click to expand...
Check the bulbs and grounds at the tailights. If there is a bad ground or an internally shorted bulb the tail,parking and dash lights could be back fed when the brakes are applied.
 
You put in new tail light wiring, is this the black and green wires to the tail light bulb socket? A Standard car has just one tail light, unless it was sold in states requiring two tail lights. What does your car have?
The wiring harness to the rear of the car has five wires:
#1 Green going to the stop light switch from the light circuit breaker. #2 second green wire from the stop light switch to the stop light bulb.
#3 Black from the light switch to the rear running light and #4 second black wire to the rear license light.
#5 Yellow to the gas tank sending unit.
Make sure these are connected properly at the rear of the car. Could be someone used both black wires for both the tail light and the license light.
 
4dFord/SC......thx....I was looking for something else or course I really didn't know what the heck I was looking for !! Going to check this out now to see what I can see !

Thx....Mike
 
41Ford and Terry will get back after awhile.......Visually I know what I'm looking for now.

Thx....Mike
 
41 and Terry......NOW I know what I'm looking for and found it. Will do more checking later, but in response to your comments.....the car did have only one tail light, but in Michigan we require two so I put the right side in. In response to 41...."maybe" I don't have that tail light grounded properly ! I'll be checking that out.

Terry.....since I added the other tail light ...I then needed to wire it across the back and I also bought new wiring that goes up front to stop lite switch & light switch on dash. I ran the wire first along side the old and then took out the old, so I am trying to figure out what I may have done wrong. There was only two wires that ran up front with the pigtail that runs off to stop light switch. Plate light works.....headlights and tail lights work.....and gas gauge works. It's 22º here today and I'll be in the Barn shortly.

At least now I know what the Circuit Breaker looks like !

Thx you all......Mike
 
41Ford.....I'm going to check to see if I can ground the new tail light better. It seems all other wiring is in it's proper place. My hands got cold so I am in for the day. 25º here !

Thx to all for info.

Mike42
 
More than likely, you put the brake switch power to the tail lights instead of the brake lite bulbs. The dash lites are in the same circuit with the tail lights.
 
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