1950 Plymouth Firewall Wiring

[Old Flathead]

I'm asking for some identification of some firewall components. I have numbered the items to identify if you know what they are. I think #3 is the fuse and unconnected wire to the cigarette lighter? And #4 is the top terminal on the voltage regulator. So 1 through 6 is you know.

Thanks,,  Eric

[MarcDeSoto]

I have a 48 DeSoto, so I'm not sure of all the wires you are pointing at.  I think no. 2 might be the horn relay.  Your shop manual would have the wires identified on it on the wiring diagram.  On the S-14 1950 DeSoto diagram, the horn relay has these connections:  H - green wire to horns; B - wire to neg. battery connection on solenoid; I - red wire to X terminal on turn signal flasher; I - red wire to negative terminal on coil; G - black wire to horn button.  I don't know what no. 1 is.  If one of the wires goes to the top or A terminal of the regulator, the red wire should go to the A terminal on the generator.  And a brown wire should go from the A terminal of the regulator to the bottom left terminal of the solenoid.    My 1950 DeSoto diagram does not show a relay connection for these wires.  

[Old Flathead]

Thanks Mark! This helps. I have wiring schematics, but electrical is my weak side. Knowing what the comments are gets me to the right spot on the diagram. 

[greg g]

If your car has overdrive number 1 might be the relay.  Is the fuse 20 amp?

[Old Flathead]

Thanks Greg,

It dos have overdrive, and yes it is a 20 amp fuse. 

I didn't think there was an electrical component for the overdrive? The car has a manual with a cable to put the car in and out of overdrive. If #1 is the overdrive relay, then where would the pigtail wire attached to the fuse side connect to, and what would it do?

 

Thanks, 

Eric

[Old Flathead]

Also,, I don't see 'Overdrive Relay' on my schematic?

 

[Dodgeb4ya]

1950 Plymouth's didn't come from the factory with the R10 OD's.

That's why the schematic doesn't show the OD relay.

[greg g]

That wire should go to the Ovedrive solenoid.  The relay provides current to the solenoid to provide engement, and after engagement and internal circuit to hold the solenoid in the engaged mode, ground for these circuits is provided through the governor.  So yes there are electrical components to the circuitry. There is also a kick down switch that disengages the solenoid when the throttle goes to wide open. The cable controls the switch that determines whether the OD is on and ready or is off.

 

I believe in the resource section there are schematics for wiring as per factory, and another using a manually operated switch for the relay and no automatic kick down.  With the overdrive in the transmisions freewhéels below about 30 mph, so below that speed there is no compression braking.  This occurs whether the circuits are on or off.  Also you shouldn't reverse with the OD in.  Some say there is. Reverse lockout but either mine isn't functioning or it's been bypassed my trans makes disagreeable noises if I forget to pull the cable in when I park in the garage.

[Old Flathead]

Thanks Greg!

 

Yes,, #1 is the OD Relay. There was a button under the dash. I hadn't known it's function. The 4 leads from the button go to the Relay, Coil and to the OD unit. I have driven the car and used overdrive. Never push that button. Always stopped to take it out of OD. Hope I didn't cause any damage. 

 

And the curled wired that is attached to the #3 spot, next to the fuse goes to a solenoid? 

[greg g]

That might be the wire that is supposed to power feed the relay from the battery side solenoid terminal.  Looks like it has been bypassed.  Some where in the down loads section is a wiring schematic for using the OD with a manual control for the kick down function maybe that's what's going on there along with the dash switch.