My 1948 DeSoto 3 window coupe restoration project.

[marcapra]

Today, I tried to connect my battery cables to my DeSoto for the first time since i put the body back on last summer.  I bought these cables from a major supplier many years ago.  I found out the Neg cable is very long by around 12 inches more than needed.  The Pos cable at 20" was too short.  I didn't realize this before because I was hooking up the cables with the battery resting on the tire.  I am connecting the Pos cable to the generator bracket under the generator.  Since I couldn't reach the generator bracket, I tried to connect the ground to the coil bracket.  Then, I got in the car to see if the electricity worked.  The only thing that was on was the left turn signal indicator light, which glowed a beautiful orange color.  Nothing else worked, not even the starter button.  I saw some sparking down at my feet.  I checked the wiring at the solenoid was a bit loose and one wire was completely off.  it was the ground wire that goes to the B terminal of the generator.  I don't think the coil bracket gives a good ground, so I ordered a new battery cable from Ebay.  It is red for Positive and 0 gauge, 30 inches long.  My other cables are 1 gauge, I think.  So, while I am waiting for that to be delivered, I will try to tackle the cable connection at the hand brake handle and continue wiring the car.  

[marcapra]

Now I have the battery cables connected.  I ordered a 24" 1 gauge cable for the ground from NAPA.  That was just long enough.  I returned the 0 gauge cable because I didn't like the way it fit.  The clerk also suggested that I buy a block to frame ground cable.  That seemed like a good idea so I bought a 4 gauge cable.  If you have been following the wild ride I had in the Tech section, you saw that my young friend Carl noticed that my generator was not wired right.  I put the A wire in front and the F wire in back just like the wiring diagram shows.  So I doubted his advice was correct.  But then, gradually, I began to see that he was right.  No. 1  - I looked up the generator in the Parts book and saw in the blow-up that the A terminal was in back and the F terminal was in front.  No. 2 - I saw the F stamped into the front terminal and the A stamped into the rear terminal.  No. 3 - The A terminal is the armature which requires a thicker wire and post, and that checked out.  Why Chrysler showed the A terminal in front on all of its wiring diagrams I guess we will never know.  My starter button is not working so I cranked the engine with a remote starter switch.  I had trouble installing the lower radiator hose which continued to leak, so I bought a flexible hose from NAPA, which works great.  Tonight, I filled the float chamber with gas and tried to start the engine.  It didn't even try to start, so I checked for spark.  No spark.  So tomorrow, i'm going to be troubleshooting the electrical system.  To do that, I am going to be pulling the dash.  I'm too old to crank my head and work under the dash.  Pics below show the old lower radiator hose, which is a three part hose giving lots of places to leak.  Then, the middle pics show the flexible hose I got from NAPA which fit like a glove and had no leaks.  The last pic shows the corrected generator wiring with the F green wire at the front and the thick red A wire at the rear.  The middle wire is the ground that comes from the starter solenoid.  

Edited June 8 by marcapra (see edit history)

[marcapra]

Today, instead of pulling the dash, I checked the easy things for no spark.  I made sure the high tension cables were connected.  Then, I opened the distributor cap and dragged a strip of manila paper through the points.  Then. I checked the primary wiring.  Ah ha, there it is.  I forgot to install the short wire going from the + side of the coil to the ground terminal for the points.  I primed the carburetor with some gas and turned on the ignition key.  My starter button on the dash is still not working, so I used my remote start switch to crank the engine.  Finally it started.  It didn't run for long before it stalled.  I started it several times and gradually it started to run a little better.  This doesn't concern me too much because I know when an engine hasn't run in a long time, ten months, it takes some time to get everything moving smoothly.  I will start it again tomorrow and try to get it going for a sustained amount of time.  Maybe 30 or 40 minutes.  

Edited June 9 by marcapra (see edit history)

[r1lark]

Congrats on the engine start! I enjoy following your progress via your posts. 

[Mike "Hubbie" Stearns]

Wiring diagrams don’t always show the exact configuration of an object. It’s sometimes easier to draw a diagram if terminals are switched. Mike

[marcapra]

Now that I know that the armature post and wire are a little thicker than the field post, and the generator itself has little stamped letters F, G, and A, I would not have this problem again.  Previously, I thought the shop manual was written in stone!  I started my engine again today and got it to run indefinitely.  I also polarized the generator by touching a wire to the A and Bat terminals for a second.  The oil pressure is 40 lbs.  The ammeter is on 0.  I have not seen it in charge mode yet, maybe because I just charged my battery.  The tempurature is around 170 deg.  The dash push button is not working, so my next step is to pull the dashboard out and troubleshoot the wiring.  Still need to know what terminal of the headlite switch I put the clock wire? 

 

 

[marcapra]

Here is my engine stalling today.  And how I got it restarted.  

 

 

[keiser31]

While you were cranking it, I kept saying out loud, "give it more gas". It sounds GREAT!

Edited June 11 by keiser31 (see edit history)

[CarlN-NDC]

23 hours ago, marcapra said:

Still need to know what terminal of the headlite switch I put the clock wire? 

Hi there Marc,

 

I was able to get out to my garage over the weekend and take a couple of pictures of how the clock is attached to the headlight switch in my 1948 DeSoto.  Hopefully you can see from the pictures, there are two wires attached to the back/input side of the circuit breaker that is connected to the headlight switch.  The brown wire attached to the rear circuit breaker terminal is coming directly from the ammeter.  The red wire also attached to the rear circuit breaker terminal goes to the clock.  The silver capsule in-line of the red clock wire is an in-line fuse that uses a 2 or 3 amp glass fuse.

 

I went back and reviewed your video on figuring out where to attach the clock wire.  I saw you encountered that the wire was too short to run all the way over to the ammeter.  As I'm sure you know, anything connected to the ammeter is unswitched power, meaning that as long as the battery is connected, it is always live or "hot".  Which is theoretically what you would want for a clock so it stays running while the car is not running and the ignition switch is set to off.  The rear circuit breaker terminal is acting as an extension of that unswitched power, so it is as if you were connecting the clock to one of the terminal posts on the ammeter.

 

It looks like your clock wire is the same length as mine, so it should easily reach the circuit breaker of the headlight switch.

 

I edited together the images side-by-side so you can see the original photo and an edited version where I highlighted the wires of interest.

 

Close-up view of the headlight switch and headlight switch circuit breaker.

 

Zoomed out/wide view under the center accessory panel.  You can see how the red wire for the clock is routed, along with its in-line fuse.

 

 

Carl

[marcapra]

2 hours ago, keiser31 said:

While you were cranking it, I kept saying out loud, "give it more gas". It sounds GREAT!

John, looks like you were right about more gas.  I'm always worried that I'm going to flood it.  The engine was warm, since it had been running for awhile.  But more gas is what got it started this time.  Thanks. 

[marcapra]

Carl.  Excellent explanation of the clock wiring.  Now I know where to put it.  Would that be where the heater blower motor would go too?  Is that what the wire with the tracings goes to?  My headlite switch is a bit different from yours.  It has a circuit breaker with points.  It has two studs coming out of the c.b.  Would I connect the clock and maybe the heater to one side of these studs?  

Edited June 11 by marcapra (see edit history)

[marcapra]

I'm wondering what wires go to which studs on the headlite switch.  I think the clock and heater wires go to one stud.  What wire goes to the other?  The shop manual is silent on this subject.  

 

 

Edited June 12 by marcapra (see edit history)

[Bloo]

That's a circuit breaker on the back. One post is on the side with the switch, the other (probably the hot feed) is not.

 

Didn't you post a wiring diagram? I'm not seeing it now.

 

Edited June 12 by Bloo (see edit history)

[marcapra]

Yes, I posted a diagram somewhere on the Tech Forum, but the shop manual is silent on this subject.  We are talking about heaters and clock which are accessories, so the shop manual leaves them out.  On Carl's pic he shows the clock wire going to the outside stud on the circuit breaker.  The inside stud is the one connected to the thick steel plate.  I would like to know what wire feeds into that.  It must be power from the ammeter, but that's a guess.  

 

 

Edited June 12 by marcapra (see edit history)

[Bloo]

Power from the ammeter feeds the stud at the bottom in this pic. The stud at the top is after the breaker and feeds all the purplish red lighting circuits.

 

It is a very good bet that the accessories not on the diagram connect to the bottom stud. If they have their own fuses, it is almost certain.

 

Edited June 12 by Bloo (see edit history)

[marcapra]

If you look at Carl's pic's above, he shows the ammeter and the clock wire going to the outside stud on his 48 DeSoto.  That would be like going to the top stud in the above pic.  So maybe Carl can chime in here with an explanation.  Today I connected the fuel sending unit cover to the trunk floor.  The Parts Book said the screws were 8-32 x 3/8.  But they would not fit.  So finally I got No. 6 X 3/8 sheet metal screws and they worked.  I am having a problem with my generator because it's not charging.  I have to put it on the Noco Genius to charge it up once and a while.  So I guess I'll have to take the generator and perhaps the regulator to an electric shop.   

[marcapra]

Today, I called my electric shop and told them that my ammeter is not going above 0.  The battery also is not charging from the generator, so I'm taking the generator and regulator in to the electric shop.  

[TerryB]

As usual with generators, has it been polarized after you installed it?  

[Bloo]

14 hours ago, marcapra said:

If you look at Carl's pic's above, he shows the ammeter and the clock wire going to the outside stud on his 48 DeSoto.  That would be like going to the top stud in the above pic.

I don't see how. The outside stud in his pic is equivalent to the lower stud in your pic.

 

You can see the upper stud on yours connected to the plate that feeds the switch. The inner stud on his feeds the switch.

 

[CarlN-NDC]

Hi Marc,

 

I have answers to a couple of your questions:

On 6/11/2024 at 12:58 AM, marcapra said:

Carl.  Excellent explanation of the clock wiring.  Now I know where to put it.  Would that be where the heater blower motor would go too?  Is that what the wire with the tracings goes to?  My headlite switch is a bit different from yours.  It has a circuit breaker with points.  It has two studs coming out of the c.b.  Would I connect the clock and maybe the heater to one side of these studs?

^ First addressing the heater blower motor.  That wire connects to accessory terminal post of the ignition switch (the post that only gets power when the key is on) and goes to the rear terminal of the heater motor switch.  You would not want the heater motor directly connected to the ammeter or the headlight switch.  The heater motor is not an accessory you would want live all the time and could easily drain your battery if accidentally left on.  By connecting it to the ignition switch, it is disconnected from power when the key is off and removed, no matter if the heater switch is on low, medium, or high.

 

At least in my DeSoto, there is NOT an in-line fuse for the heater motor wire.  If you notice in my picture, the heater wire is looped around the defrost cable.  There is no functional reason that I can see as to why it was routed that way.  Most likely, it was simply to prevent it from hanging down under the dash and being caught by someone's foot!  I am not sure what the original color of the wire was.  If I had to guess, it looks like it might have originally been either black or blue with a double straight tracer.

 

Second, addressing the headlight switch.  I know we recently discovered, and had a entire thread discussing, that the factory wiring diagram for the armature and field wires is incorrect.  In the case of the headlight switch, I believe the factory wiring diagram IS correct!

 

To best visualize everything, I went ahead and labeled each individual terminal on your headlight switch.  I did flip your original photo 180 degrees so that your headlight switch matched the orientation as the factory wiring diagram so you could more easily compare between the wiring diagram and the switch itself.

A note about your headlight switch, I do see that your circuit breaker is a different style compared to mine.  In my labeled picture above of your headlight switch, the top terminal is the power input terminal, which is where the brown wire coming from the ammeter connects to.  (This is also the terminal that the red clock wire should be attached to.)  You can tell it is the input terminal post because of the black backing paper underneath the terminal.  The black backing paper insulates/isolates it from the rest of the headlight switch.  So electricity must flow through the breaker points before power can reach the adjacent terminal post or any of the bullet terminals on the switch.  Hopefully my labeling also answers your question of what wire(s) connect to the adjacent terminal post (Which is the bottom terminal post in the picture above).

 

Finally, just for a comparison, here is a close-up picture of my headlight switch.  As far as I can tell, the wires have never been touched since they were installed at the factory 76 years ago!  While the wires are faded, there is still enough color left to see that all of the wires match the colors and positions compared to the factory diagram.   Also, notice the thickness of the black heat shrink over the ring terminal that connects to the rear terminal post.  It is hard to tell from my picture, you can't even see all of the wires, but there are three wires (stop light, map light, and dome light) all tied into that one ring terminal.  I am not sure if your reproduction wiring harness has all three of the aforementioned wires bundled together, or if they have individual ring terminals.

 

 

I hope this answers several of your questions!

 

Carl

[marcapra]

Carl,  that's a lot of good info.  Thanks!  According to my wiring diagram things like the brake light, dome light etc. go to bayonet terminals.  No mention is made of the two studs.  For example the brake light goes to the A terminal.  But I've learned that you can't take the shop manual as gospel.  I have several NOS light switches, one of them is like yours.  The end of the outside stud on this light switch says BAT.  The reason I said what I did about my light switch is when you look at the outside of this C.B., it looks like the top stud of my light switch above, but maybe yours is different?  So, now that my generator and NOS regulator are at the electric shop, I have some time to pull my dash and correct some of my wiring.  

Edited June 14 by marcapra (see edit history)

[Bloo]

The current flows from the ammeter wire through the circuit breaker to get to the light switch (see the wiring diagram). What the terminals or posts look like does not matter. Follow the current path from the ammeter through the circuit breaker to get to the light switch and all will become clear. It works for either switch.

 

P.S. If you have a switch like CarlN-NDC's switch, why don't you use it? The circuit breaker in his pictures is a generic type used on things like snowplows even today. In the unlikely event of a failure, it is replaceable separately from the headlight switch, just get the current rating off of the old one or better yet take the old one to NAPA and match it up. It won't be by make model and year, it is a generic aftermarket part. On that switch you have been posting pictures of, should the breaker fail, you have to replace the whole switch.

 

 

[marcapra]

Thanks Bloo and Carl.  I think from Carl's description that I may know now where the radio would connect.  I think it would be the same stud as where the clock connects.  I was thinking that the radio would connect to the accessory terminal of the ignition switch, but I think I remember being able to listen to the radio when the engine was not running.  When I look at the wiring diagram now, I see the the three red wires, one of them is the brake light, going to the light switch.  I don't see them going to a socket.  They just go in the edge of the switch.  That's the upper stud that Carl was talking about.  

Edited June 14 by marcapra (see edit history)

[marcapra]

10 hours ago, TerryB said:

As usual with generators, has it been polarized after you installed it?  

Yes, I polarized it, I think, at the voltage regulator by placing a wire on the Bat terminal and the other end on the ARM terminal until I saw a spark.  

[marcapra]

Today, I pulled the dash.  I'm a bit too old to be cranking my neck under a dark dashboard!  It's kind of a tough job to do alone.  But with the help of a crate and boxes, I am able to prevent the dash from falling on one side as I pull it out.  To do this, I had to undo a lot of work:  drain radiator,  remove temperature, oil and speedometer lines.  Unplug the wiper motor and remove the gear shift.  But I got it safely on the seat so I can easily access the back.  I checked the push button that didn't work and it had continuity, but maybe the button was not cinched up as tight as it could be making for a poor ground.  These are the wiring instructions I got when I ordered a wiring harness back in the 80s.  It says it's for sedans and convertibles.  Maybe it will fit my coupe or maybe not for all lights.  Or maybe it will just have a couple of extra wires for rear passenger door courtesy lights.  I think the guy who type up this instruction sheet didn't know about DeSotos being postive ground.  Wire no. 48 says - neg side of coil goes to breaker points terminal!  

Edited June 15 by marcapra (see edit history)

[marcapra]

I took some close ups of the light switch to see if I needed to change anything.  I changed the clock wire from the ignition switch to the light switch stud, the one with the hot wire coming from the ammeter.  There are three red wires going to the other stud, so I think that is where Carl said they go.  My heater blower motor has two terminals.  I know from Carl that one of them goes to the ignition switch.  Where does the other wire go to?  And am I right to think that the radio wire would go to the hot side of the light switch with the clock wire?  

[marcapra]

6 hours ago, marcapra said:

 Where does the other wire go to?  And am I right to think that the radio wire would go to the hot side of the light switch with the clock wire?  

After doing some research, I know a lot more than I knew when I wrote my question. The power wire, called the A lead, goes to the RAD terminal on the ignition switch. If you look at the back of an ignition switch, it has little letters stamped next to the terminals. The RAD terminal is the tall stud. I guess that means that the radio will only work when the engine is running, since there is no accessory position on the ignition switch, which came in 49 or 50. I used to have a 50 Windsor and remember listening to the radio when the engine was off because I had the key on the ACC postion. So I thought my 48 would be the same, but apparently not. I made the mistake of connecting my clock wire to the RAD terminal and the clock only ticked when the engine was on. So I moved the clock wire to the stud on the headlite switch, which is hot all the time. If your radio hums or doesn't work, you should watch this 1951 Chrysler filmstrip on how to fix radios.. https://mymopar.com/mtsc-1951-volume-4-7-automobile.../

 

MYMOPAR.COM

MTSC – 1951, Volume 4-7 Automobile Radio Service – MyMopar

 

[marcapra]

On the blower motor, is the green wire here the one that would go to the ignition switch?  There is another terminal.  Do you know where that wire would go?  

[marcapra]

AFter watching the 1951 Master Tech filmstrip on radios, I'm wondering about the 14 amp fuse the 51 radios had.  I can't find a fuse or holder on my 802 radio.  Could it be that the 48 and earlier radios didn't have a fuse?  It would seem mandatory that all radios have a fuse.  Also my antenna cable broke off.  Maybe they sell new ones?  The Voice, Mello, and Music tone control paper broke off at the bottom of the dial, and I don't think the radio light changes colors when you change the tone control.  I wonder if that can be restored?

Edited June 15 by marcapra (see edit history)

[Mike "Hubbie" Stearns]

IMO , there’s only three circuits that should be powered when key is off. Headlight/tail lights, hazards, and power to ignition switch. Mike

[Bloo]

I'd add brake lights to that list if we are talking about "should". Running a bunch more current through an ignition switch than the maker intended though is not likely to end well.

 

I think marcapra is on the right track trying to get things connected the way Desoto would have. Vacuum tube radios for instance draw a lot of current. If one wants everything non-essential to shut down with the key, I think it would be best to add a relay.

 

[marcapra]

I found a MoPar 802 radio installation instructions in a very complete Dodge D-24 Owner's Manual envelope.  My A lead doesn't have the fuse holder because it has broken off.  The A lead which goes to the RAD terminal of the ignition switch does take a 14 amp fuse.  There are also several radio noise suppression devices it says to apply.  I know about the condenser that goes on the generator with a lead that goes to the A terminial.  But there is a suppresor that goes on the coil to distributor cable, and a condenser that goes on the back of the fuel gauge.  I never heard of that.  Also it says to ground all the lines that go through the cowl, such as the temp, oil, and speedo lines, as well as the hand brake cable!  

[marcapra]

When I said that on 48 and previous MoPar models, you can't listen to the radio when the ignition key is not on, I was wrong.  I just read in a 1942 DeSoto owner's manual that you can listen to the radio and run anything else connected to the RAD terminal if you turn the key to the left.  Carl also told me that.  So I tried to turn my key to the left and it doesn't go.  Also, I don't get any cranking when I push the starter button.  I can crank with the remote switch, but nothing happens with the push button on the dash.  I checked continuity on the two terminals of the push button and it's good.  Does the ign. key need to be on to crank the engine.  I would think so.  I tried it, but it would not crank.  I guess I need to check continuity between the button and the fuel gauge and the button and the starter solenoid.  But my tester can't reach that far, so I need to look for a tester with long leads with alligator clips, but I don't think those exist!

Edited June 16 by marcapra (see edit history)

[Bloo]

Check for voltage on the yellow and black wire at the starter while someone presses the button.

 

[marcapra]

I found long test leads with alligator clips that you can plug into your multi tester.  Also I think the second terminal on the blower motor, shown above, connects to the wire coming out of the blower motor.  

[marcapra]

Sometimes it pays to double check your work.  I put a shop light up to the starter solennoid and saw that nothing was connected to the terminal where wire 27, coming from the push button, was supposed to be connected.  I looked around for wire 27 and couldn't find it.  Then, I finally found it hanging and hiding under the steering post.  Hey, with work like this maybe I could get a job at Boeing.  I will connect it tomorrow.  It's tough to get to because the guy who rebuilt my solenoid put the wires meant for the top right on the top left and vice versa.  That makes getting the inside post very difficult because the the oil filter and lines are in the way of my fingers!  Also, I found out I can turn the ignition key to the left, but I have to have light touch to do it.  I found an original 1946 Comfort Master All Weather Control System owner's brochure in a Dodge owner's manual envelope.  

Edited June 16 by marcapra (see edit history)

[marcapra]

I had to remove the oil filter to get to the top inside post of the solenoid.  After attaching the wire 27, the engine finally cranks from the push button.  It cranks whether you turn the key left or right.  I'm going to finish up the wiring under the dash by tomorrow and have the dash installed again.  Then, I'm hoping the electric shop calls me soon so I can pick up my generator and regulator.  While I'm waiting, I hope to install the new hand brake cable that I ordered from AB.  And here is the plaque that I got for hosting the 1988 Nat. DeSoto Convention in Carlsbad, CA.  Kind of shows how long I've been at this!  

[marcapra]

On 6/15/2024 at 2:50 AM, Mike "Hubbie" Stearns said:

IMO , there’s only three circuits that should be powered when key is off. Headlight/tail lights, hazards, and power to ignition switch. Mike

I don't think the ignition would be powered when the key is off.  If it was it would burn up the points and run down the battery.  

[Mike "Hubbie" Stearns]

1 hour ago, marcapra said:

I don't think the ignition would be powered when the key is off.  If it was it would burn up the points and run down the battery.  

I said ignition switch, not ignition. If the ignition was powered, you couldn’t shut off the engine. Mike

[Bloo]

That is confusing.

 

I believe that key to the left should get you everything that is shut of by the key EXCEPT the ignition coil, in case you have some reason to leave the key on but don't want to burn up the points.  Key to the right should add the ignition coil so the engine can run.