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And the Prince of Darkness reigns for ever and ever, as long as the people love their English cars...

 

Why do the Brits drink their beer and ale at room temperature?

 

Because they have Lucas refrigerators!

 

Keith, that was an excellent post. Simple and concise, automotive electric 101 put in terms a layman should be able to understand. My vote for post of the day, or do we still have that?

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  • 4 months later...

In response to Keith's informative post, the partial shop manual that came with the car, (I have one ordered)  The part of the index that is there indicates the "lighting system" is controled by a circuit breaker. It dosen't say if it is the entire lighting system or not. Presently the headlights & parking lights work since I replaced all the sockets, headlights were no issue. However, no horn from the wheel, I think it's missing a part in the horn ring. and no turn signals, I'm looking for a 6 volt flasher. Question is how much or all of the electricial system on my 49 Chrysler is controlled by this circuit breaker?  BTW: the old flasher was screwed to the firewall under the hood, it had aflange for mounting, do these need to be grounded? On my 12vt cars, the flashers are just hanging under the dash   

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I have a 1949 Canadian Mopar service manual here. I can view schematics of 1949 C45 and C46 models. The circuits are different as the C46 seems to have more bells and whistles. Including electric door locks, and electric convertible motor. 

 

The C45 has one 3 amp window wiper motor circuit breaker and another circuit breaker (amp rating unspecified in the schematic) for the entire lighting circuit. It's right off the ammeter, then on to both the live wired lights, (door jamb interior lamps, brake lamps), and also headlamp switch controlled lights. 

 

The C46 has an 8 amp circuit breaker that feeds the window wiper motor. Then another 30 amp circuit breaker. It protects the head light switch circuit, glove box light,  map and panel light switch,  some type of front & rear door switches (electric locks I assume). I also see a 3rd circuit breaker. It seems to mainly protect the semi-auto shift system for the transmission. (shift solenoid, interrupter switch, anti-stall switch). 

 

I'm still learning here too. It seems odd to me that there is no circuit breaker for the C46 convertible roof motor. It pulls power right off the starter lug (battery wire) to a switch. Gotta be quite a heavy amp-rated switch I suspect to run that motor. Seems questionable today.

 

I don't see any ground wires needed for flashers. The circuit is grounded at each signal bulb.

 

Circuit breakers. Help me understand. Are they designed to kill the circuit once the amp draw going thru them gets too high? A thermal switch that automatically resets once it cools down? I can see a wiper motor, or all the headlights are needed for safety. Too high of a draw, yet a person still needs to get home. So it cools and resets, as opposed to a fuse that melts and cannot be re-set?

 

Sorry @Handyman I may not have answered your question. Only added some color and raised more questions.

Edited by keithb7 (see edit history)
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I believe the lights circuit breaker is 30A.  Circuit breakers are typically two types, the manual reset type and the self resetting type.  Given the location of the Chrysler ones, self resetting would make sense.   

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Everything I've found so far indicates various self resettting  breakers as Terryb indicated.  The  book, or at least the part of it i have,  indicates the headlights have a breaker just for them. Then another, (on a C45) for the rest of the accessories including the flashers which are now operating once I figured out what the letters on each blade on the flasher was for.  BTW, i got the shop manual I sent for, It's a DVD,,, & is going backl  Both my 56 Wjndsor & 60  Adventurer have similliar systems but with in line fuses for some accessories. My 68 Newport has a fuse block with 1 breaker.  As we speak, err write, the only two issues left, (electric wise) are the brake lights. I clamped the brake pedel in the down position useing the steeirng column. I have nothing coming out of either brake light leads. anyone know where the brake light switch is? Lastly, is there a horn ring assembly pic out there, I have a horn when I ground the center lead but not with the horn ring assembled. I'm not sure all the parts are there.  

Really appreciate the responses, Hell of a site!

Handyman 

Edited by Handyman
spelling (see edit history)
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On 1/19/2021 at 12:56 PM, keithb7 said:

I have a 1949 Canadian Mopar service manual here. I can view schematics of 1949 C45 and C46 models. The circuits are different as the C46 seems to have more bells and whistles. Including electric door locks, and electric convertible motor. 

 

The C45 has one 3 amp window wiper motor circuit breaker and another circuit breaker (amp rating unspecified in the schematic) for the entire lighting circuit. It's right off the ammeter, then on to both the live wired lights, (door jamb interior lamps, brake lamps), and also headlamp switch controlled lights. 

 

The C46 has an 8 amp circuit breaker that feeds the window wiper motor. Then another 30 amp circuit breaker. It protects the head light switch circuit, glove box light,  map and panel light switch,  some type of front & rear door switches (electric locks I assume). I also see a 3rd circuit breaker. It seems to mainly protect the semi-auto shift system for the transmission. (shift solenoid, interrupter switch, anti-stall switch). 

 

I'm still learning here too. It seems odd to me that there is no circuit breaker for the C46 convertible roof motor. It pulls power right off the starter lug (battery wire) to a switch. Gotta be quite a heavy amp-rated switch I suspect to run that motor. Seems questionable today.

 

I don't see any ground wires needed for flashers. The circuit is grounded at each signal bulb.

 

Circuit breakers. Help me understand. Are they designed to kill the circuit once the amp draw going thru them gets too high? A thermal switch that automatically resets once it cools down? I can see a wiper motor, or all the headlights are needed for safety. Too high of a draw, yet a person still needs to get home. So it cools and resets, as opposed to a fuse that melts and cannot be re-set?

 

Sorry @Handyman I may not have answered your question. Only added some color and raised more questions.

 

Yes, the circuit breaker (or a fuse) is designed to break the circuit when a certain amount of current is drawn. ie in the event of the mechanism of the window or roof gets jammed. When this happens, the electric motor goes into a runaway situation and continue s to draw more and more current to turn the armature and burns up if the wires feeding don't burn first.

 

Always fuse an electric motor.

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31 minutes ago, TerryB said:

A two terminal pressure activated switch mounted in the master cylinder.

 

If you don't find it there just follow the brake lines.

For some reason I keep thinking near the radiator.

For troubleshooting, pull both wires and hook them together, you should get brake lights. If not check to see if you have voltage to one of them with a test light or meter. 

These pressure switches are famous for failing.

Should look something like this.

 

Brake Light Switch Kit w/Brass Tee Fitting, 3/8-24 IFF, 1/8 NPT
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On 1/23/2021 at 5:28 PM, Handyman said:

i got the shop manual I sent for, It's a DVD,,, & is going backl 

 

I also like printed shop manuals, for perusing. But, having a digital copy is GREAT! I can load it onto my iPad, or simply print the pages I need for a particular repair and not worry about getting grease all over the printed shop manual. I used to use a copier to make working pages from printed shop manuals. The digital version is easier to print from.👍

 

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