‘36 dodge truck electrical

[Rodney_Hamon]

Yesterday I got my headlights/taillights to work with the new universal headlight switch. It replaced the old universal switch from 1975. First time working since 1986.  Almost cried either from relief or happiness. I found bad terminal ends on wires from the switches to the ammeter. I also went up under the dash and cleaned connections. Battery was disconnected when doing this and it’s apparent I have to really go over every connection.  I have no light for the instruments but will search my parts for the missing bulb housing.  Horn does not work but will solve that also. I elected to buy from DCM the 2 important switches and horn relay to replace what was already there. Sitting for 35 years caused a lot of oxidation. The switches and relay were pretty identical to the ones replaced. I think they were Cole Hearse originally. I will need advice the next time I post as there are mysteries to the wiring circuit compared to the diagram in the service manual. The overdrive has its challenges also. Anyway, after recovering from gall bladder procedures I am fit to crawl/contort and bend over once again...until the back days no.  Ha.  Merry Xmas everyone and thank you for your support. This forum is awesome ? 

[Rodney_Hamon]

I have a question about this light relay.  Is this a universal relay ?  It had yellow marker on it and looked used as I remember even back in 1975.  It works   as I have lights, hi and low beam since replacing the dimmer switch and I also have a dash light working for the hi beam.  

[Rodney_Hamon]

I moved on to the next mystery relay.. for the horn. Reading other horn stories it seems one horn does not need a relay. The wiring diagram also indicates this but some say it is a good idea anyway. The relay in the picture is a mystery to me. The horn never worked. It is an electric auto-lite 6 volt and I’m guessing it is original to the truck.  I disassembled it partly today to check out the inside. It is pretty clean and solid. The points are stiff to open and I was hesitant to take this apart as it seems clean enough. Should points be stiff? I gently opened the points and pulled a match striker strip across since I couldn’t get a point file in there.  I sprayed some CRC into areas and wiped with q tips. The gasket was intact when pulling the housing apart so I will gently bolt it back together with cleaned up bolts etc. Next post will show a better picture of the horn and then a question as to the wire hookups. 

[Rodney_Hamon]

Last night I searched any information about this horn..how to and what is it.  Then I saw that it resembled a ‘40’s era horn. Then a memory hit. When I bought this ‘36 it had a smoking ‘42 engine. That was replaced with the D-30 that is in it now. Then I realized that this may be a ‘42 horn.  It’s stamped 6volt on the back. I put it back together and adjusted the set screws on the back and achieved a full circuit from the battery with grounds connected and test light to power. Nada. Shame. The bracket that fits this horn is underneath head bolts so that remains. I’m just going to rob a horn from the P-23 parts car and see if that works. Then I’ll find out if the horn button works.  At least I learned more about horns. 

[Boody]

The 2 connectors on the horn is positive  and the other negative?

[bkahler]

12 hours ago, Boody said:

The 2 connectors on the horn is positive  and the other negative?

 

I don't think the posts are positive and negative per say, but the battery should be connected negative to one post and positive to the other post.  I don't think the metal casing is connected to either of the posts.  It's been a while so I could be wrong.....

[Merle Coggins]

I’m no expert on the internals of the horn, but it appears that there is a section of wire missing between the upper and lower connection points on the left side in that one picture. Is that wire needed to complete the circuit? 

[bkahler]

1 hour ago, Merle Coggins said:

I’m no expert on the internals of the horn, but it appears that there is a section of wire missing between the upper and lower connection points on the left side in that one picture. Is that wire needed to complete the circuit? 

 

I zoomed in on the picture and it looks like the black wire on the left connects the top and the bottom.  Just kinda hard to see.   

[Rodney_Hamon]

Yes, all the wires seem very solid and connected well except the one wire goes into the windings and that seemed odd and the points are closed tight with no way to adjust. I’m confused how that works. I understand the theory of the magnet like a speaker though. I removed the double horns from the cranbrook parts car and hooked up to a battery and BOOM. Quite loud! They both worked and had high and low tone. I chose the lower tone horn as the temporary donor.  Silly me, I bolted it excitedly to my truck engine and hooked up the power and ground wire from the horn button and...blew the fuse on the ammeter. Oops.  Disconnected and realized the horn button must have issues.  At least I got this far. Eventually I want to buy another horn similar to my dead one or find someone to fix it. In the meantime I will mess around with the horn button and set up the cranbrook one with the relay. I’ve now seen horns on the AACA and HAMB site for trucks for my era. Informative. 

[Merle Coggins]

I believe the way the horn works is that with the points closed you have a complete circuit that will allow the electro-magnet to energize. This should pull the points open, which breaks the circuit and de-energizes the magnet, points close again and re-energize the magnet, points open and de-energize the magnet, etc., etc. This causes a buzzing as the points open and close rapidly. The buzz is amplified through the trumpet part of the horn. 

[Rodney_Hamon]

Agreed to how the points then work to complete the circuit.  I guess my magnet will not pull the points open.  So on to my question regarding relays for the new temp horn. I have a hot coming from the ammeter to the B (battery)on the relay. Horn button wire fed from the steering wheel column attaches to the H (horn) on the relay. Circuit completed for the armature inside the relay. Is this correct?  Do I ignore the S terminal on the old relay and the similar terminal (5) on the new relay. Hopefully in the pix you can see the schematic printed on it. I’m asking any sage on this to repeat blowing fuses on the ammeter. I still have not popped off the horn button to see what’s inside. I wanted to read more before I open up the new can of worms for the new year. Ha. Thanks all for your patience with my lack of electrical and horn expertise. 

[lostviking]

Hot goes to the common terminal. The line, top right goes to the load. The right coil goes to whatever switches it.

[Merle Coggins]

H,B,S, would be Horn, Battery, Switch. On your other one, according to the diagram on the side, 3 is your battery (power) connection, 1 is the output to the horn, and 5 would go to your horn button to provide the ground to activate the relay. 

If you are blowing a fuse it may be that your horn is shorted out causing a direct ground when power is applied.Can you temporarily connect your power feed wire directly to the horn and get it to sound off without blowing the fuse? 

Edited January 1, 2022 by Merle Coggins

[Rodney_Hamon]

No to the direct power to the old horn. No sound. I am understanding the relays better now. 1 output to the horn with the new relay is simply connecting it with a wire from that 1 terminal to a bolt that will attach the ‘51 horn to the bracket. On the cranbrook, both horns in series have one screw that power connects to. The pair simply grounds to the chassis. Of course when you follow the wiring there is a busy pathway to terminal block and then back to a relay. Parts car is kinda garbaged. I also looked at wiring diagrams for a P-23 and my dodge. The schematic on the new relay makes better sense now.  Thanks for helping!   

[Merle Coggins]

If there is only one terminal on the horn then it is a power terminal, and the horn is grounded through the mount. On that type of horn you need to use a relay as the horn switch/button is a grounding switch. It can’t supply a power source to the horn(s).  The horn button activates the relay which then relays power to the horn(s). The truck horns, with 2 terminals, have a constant power feed to one terminal and the horn button provides the ground for the second terminal to complete the circuit.

 

 

[Rodney_Hamon]

Thanks for the clarification on the horn button being a grounding switch. I’ll be honest..2 out of 3 terminals on the relay understood. The gateway on the relay diagram had me confused from #3 going to #1 (output to horn). When the term “common” is used I go into house wiring mode of the white wire being ground ultimately connecting to the buss bar in the breaker box. 

[Merle Coggins]

Usually a "common" terminal is only used on a switch that has normally open (NO) and normally closed (NC) contacts. The "common" terminal would be the input, and the output would be the NC terminal when the switch is at rest. Then the output changes to the NO contacts when the switch is activated. Your relay doesn't have this type of switch. 

 

If you look at the diagram on the side of the relay it shows terminal 3 branches and connects to the switch contact and also to the coil. 5 goes to the horn button and when pressed it supplies a ground for the coil circuit. This will energize the coil, and magnetize it, which pulls the contacts closed. Once the contacts close on the switch the input voltage at 3 passes through to 1 and sends voltage to your horns.  

[lostviking]

The term common was used because I don't usually expect other people to have 40 years of engineering behind them, and it was used because the diagram showed it "going" to each of the other terminals. I explained the relay in common terms, not the functions specific to the application. It was only meant to illustrate that power goes in the terminal on the left, the load is connected to the upper right and the coil, shown, is grounded at the lower left.

 

The white wire in house wiring is not ground. It is neutral. There is a very big difference.

[Rodney_Hamon]

Lostviking, you are absolutely correct about house white common being neutral. My bad. Yes, I need to think like Romex 12/2. Ground wire separate. Between you and Merle I am learning auto electrical 101 and I appreciate explanations.  All these years I had a mechanic or auto technician do the electrical. Never touched it much. Let the professional do that but shops are declining and too far away. I need to figure this out and stop my avoidance behavior with it.  Today I got the stubborn horn button off and cleaned contact components. I think nothing is missing.  I am reluctant to try and loosen the steering wheel nut to clean that brass piece under it as my steering wheel is cracked all over. With extra light in the cab I just noticed how bad it was. . So I will steel wool and lightly sand with 400 grit. I temporarily installed the horn with the relay. Power is to it and power is to the steering wheel through the wire. Tomorrow I will finish cleaning and will test and let you know if it honks. Again, thanks for helping. 

[Rodney_Hamon]

Got the horn to work but it takes several pressings of the horn button. I think the contact between the end of the wire point and the button spring are in question. I only have the ‘37 dodge truck shop manual to see an exploded view of the steering gear. I don’t have a ‘36 shop manual as they have been hard to find. I have the ‘34-‘36 master maintenance manual but it doesn’t have the steering gear pix. I am assuming they are very similar though. The order of my horn button components are out of order from the pix I see in the ‘37 shop manual. Anyway, I’ll mess around with it to see if I can get better contact and toot from the horn. From the picture you can see I bolted the relay to the back of the horn for now. I didn’t want it vertical to catch dirt but I will play with a horizontal  orientation later. The important thing was to get the horn circuit working for the first time since I bought this truck in 1974. Anybody know if the horn button parts are the same for ‘36 and ‘37 ?

[ggdad1951]

sounds like you have some corrosion maybe in the contact line someplace...or weak contact....does this horn have adjustments like the B series does?

[Rodney_Hamon]

I think it’s a weak contact. Google searching and reading does not show my exact set up. I think I have all the parts but the wire/cable contact end seems a tad recessed into the Bakelite wheel but insulator. Wondering if I could slip a retainer clip under that wire end to bring the height up tiny bit for better contact. I tried to build up the height of the horn button assembly with a thin strip of brass shim but I could not screw the button back on. The main spring seems adequate. I wonder if the smaller horn spring is compressed too much. Not very tall. So close...

[Rodney_Hamon]

Success. I found a thin brass washer and cut a slit opening in order to slip it under/behind the wire end fitting. A little bit of a recess in the Bakelite washer was not allowing the wire end to contact the horn ring very well. Phew!  I do not see any adjustment on this horn. It honks adequately now. Now on to the windshield wiper motor. I have a 6 volt Bosch that replaced the vacuum motor. My dad found it somewhere back in ‘75 and because it was shallow in depth it fit. One speed as I remember. Right now it doesn’t operate. 

[Young Ed]

Those were optional electric wipers. Usually I've seen them on bigger trucks. Should have a matching knob for the dash knobs with no label. 

[Rodney_Hamon]

That’s good to know about the origin of this wiper motor. I got it to operate yesterday with some liquid wrench. I don’t have the knob so the toggle sw will have to do for now.