BobT-47P15 Posted January 21, 2014 Report Share Posted January 21, 2014 (edited) I guess I just discovered something about the horn relay on these cars. The one that was on my car was a Delco HRL 4104 model. It has four connections - for "battery", "ground", "ignition", and "horn". The exact hookup of these items is shown on the wiring diagram available at the back of the P15 Service Manual. Then I looked at some similar appearing relays, I think were taken off a slightly newer model Plymouth (like 1950, 1951 or so) ..... where they mount on the firewall rather than the horn bracket up front. Model HRL 4101. They have the same hookup designations stamped on the mounting bracket. Both are 6 volts. So, it would appear you can use either model on P15 horns. The model of relay is stamped into the side of it. Our Parts Manual gives a Mopar part number for these relays, but does not tell the rest of the story.......what brand relay and what model. And, I have never found or bought a Delco manual.......which might be a rather handy thing to have. The relays look like this........... (4101 on left) (4104 on right) And mount here on P15........ Edited January 21, 2014 by BobT-47P15 Quote Link to comment Share on other sites More sharing options...
BobT-47P15 Posted January 21, 2014 Author Report Share Posted January 21, 2014 Also on horn relays.......I found in my collection a Delco RAH 4002 horn relay.....it's marked 12 volts.....with same connections. Just FYI. Then..............lastly...........I have two of these larger relays with a fuse........can't find any model number on them. The connecting points are marked with a "H", and an "S".........with a "B" right by the fuse. No idea what they are for or what car uses them. Anyone know?? I thought at one time I had a couple relays for the headlights......but had never installed them......and don't recall much about them now. Don't know if that would be these. Quote Link to comment Share on other sites More sharing options...
Young Ed Posted January 21, 2014 Report Share Posted January 21, 2014 And mount here on P15........ Only on early cars. The later cars the headlight relay got moved to the inner fender by the solenoid. Quote Link to comment Share on other sites More sharing options...
BobT-47P15 Posted January 21, 2014 Author Report Share Posted January 21, 2014 OK........what do you consider "early cars"? Later cars? Don't recall seeing a relay near the solenoid. There were posts about headlight relays in the past.....will see if I can find them. Quote Link to comment Share on other sites More sharing options...
desoto1939 Posted January 21, 2014 Report Share Posted January 21, 2014 Also on horn relays.......I found in my collection a Delco RAH 4002 horn relay.....it's marked 12 volts.....with same connections. Just FYI. Then..............lastly...........I have two of these larger relays with a fuse........can't find any model number on them. The connecting points are marked with a "H", and an "S".........with a "B" right by the fuse. No idea what they are for or what car uses them. Anyone know?? I thought at one time I had a couple relays for the headlights......but had never installed them......and don't recall much about them now. Don't know if that would be these. These are single light headlight relays. They do make dual headlight relays. H = headlight S= Switch or dimmer switch foot floor board switch and B=Battery. So you would hook up one relay to the low bean and then one for the high beam if you have single lights or if double headlights then one to each light. Rich HArtung Desoto1939@aol.com Quote Link to comment Share on other sites More sharing options...
Don Coatney Posted January 21, 2014 Report Share Posted January 21, 2014 These are single light headlight relays. They do make dual headlight relays. H = headlight S= Switch or dimmer switch foot floor board switch and B=Battery. So you would hook up one relay to the low bean and then one for the high beam if you have single lights or if double headlights then one to each light. Rich HArtung Desoto1939@aol.com I don't understand the need for two relays. If the headlight relay is placed after the headlight switch and before the dimmer switch then one relay will fire both high and low beams. The contacts in the dimmer switch are designed to carry the amperage of both low and high beams. I am open to suggestions if my logic is incorrect. Quote Link to comment Share on other sites More sharing options...
Young Ed Posted January 21, 2014 Report Share Posted January 21, 2014 OK........what do you consider "early cars"? Later cars? Don't recall seeing a relay near the solenoid. There were posts about headlight relays in the past.....will see if I can find them. I don't know the exact model break for the change. Perhaps at the same time when they switched to 15" wheels? The parts book might show a serial # break for the wiring harness change. It could also be a variation from plant to plant? Quote Link to comment Share on other sites More sharing options...
_shel_ny Posted January 21, 2014 Report Share Posted January 21, 2014 4101 vs 4104 horn relay. Difference is: 4101 has a screw to hold the ground wire where the 4104 has the female for a bullet connector. Quote Link to comment Share on other sites More sharing options...
desoto1939 Posted January 21, 2014 Report Share Posted January 21, 2014 Don. The two switches are placed after the dimmer switch. This is done so that the relays are used to get the increased volts or power to the lights. I have a double headlight rely and there are separate connections for the low beam and then the high beam. So the headlight switch provides the power to the dimmer switch. You have a direct 10 gage wire from the battery source to power the rely or each relay. Then a line from the low beam contact on the dimmer switch to the single S on the one that will be used for the low beam. Then the H on this unit is attached to headlight bar to the corresponding low beam. Now the low beam rely is doing the work of powering the headlight instead of the electricity going through the headlight switch down to the dimmer switch and then out to the headlight. Then you setup the highbeam rely in the same manner but then you connect to the highbeam connection on the headlight bar. If you are in doubt then I will look to find my instruction sheet. I have had a dual rely on my 39 Desoto for 20 plus years. Rich Hartung desoto1939@aol.com 1 Quote Link to comment Share on other sites More sharing options...
Don Coatney Posted January 22, 2014 Report Share Posted January 22, 2014 Don. The two switches are placed after the dimmer switch. This is done so that the relays are used to get the increased volts or power to the lights. I have a double headlight rely and there are separate connections for the low beam and then the high beam. So the headlight switch provides the power to the dimmer switch. You have a direct 10 gage wire from the battery source to power the rely or each relay. Then a line from the low beam contact on the dimmer switch to the single S on the one that will be used for the low beam. Then the H on this unit is attached to headlight bar to the corresponding low beam. Now the low beam rely is doing the work of powering the headlight instead of the electricity going through the headlight switch down to the dimmer switch and then out to the headlight. Then you setup the highbeam rely in the same manner but then you connect to the highbeam connection on the headlight bar. If you are in doubt then I will look to find my instruction sheet. I have had a dual rely on my 39 Desoto for 20 plus years. Rich Hartung desoto1939@aol.com Rich, I understand how you have it wired and I am sure it works well. But this seems a bit redundant to me. The weak point in the system is the headlight switch not the dimmer switch. I believe using one relay will give the same results. So it is a matter of personal preference. Quote Link to comment Share on other sites More sharing options...
BobT-47P15 Posted January 22, 2014 Author Report Share Posted January 22, 2014 (edited) OK.........next question........I am replacing the original style headlights with halogen units...........would a person still want to use the relay with them? Rich - if you find that relay diagram......could you send me a copy? email.....snail mail....whatever. Edited January 22, 2014 by BobT-47P15 Quote Link to comment Share on other sites More sharing options...
martybose Posted January 22, 2014 Report Share Posted January 22, 2014 OK.........next question........I am replacing the original style headlights with halogen units...........would a person still want to use the relay with them? Rich - if you find that relay diagram......could you send me a copy? email.....snail mail....whatever. Yes, you want the relays! Don't forget that the original headlights were roughly 35 watts, and the halogens are usually 65 watts. Don and I have argued this point before, but when I put 6V 65W halogens in my car the headlight switch and the dimmer switch both got pretty hot until I put in headlight relays and used a larger gauge wire to the headlights themselves. Marty Quote Link to comment Share on other sites More sharing options...
deathbound Posted January 22, 2014 Report Share Posted January 22, 2014 OK.........next question........I am replacing the original style headlights with halogen units...........would a person still want to use the relay with them? Rich - if you find that relay diagram......could you send me a copy? email.....snail mail....whatever. Or, if possible, post a copy to this thread. Quote Link to comment Share on other sites More sharing options...
desoto1939 Posted January 23, 2014 Report Share Posted January 23, 2014 headlight rely instruction sheet Will try to post it here I tried to up load the files. ever since we moved to the new formatted forum I can not ever post any pictures or documents. if you want a copy of the instruction then send me an email and I will send you an attachment. Rich Hartung Desoto1939@aol.com Quote Link to comment Share on other sites More sharing options...
OldDad67 Posted February 8, 2014 Report Share Posted February 8, 2014 OK........what do you consider "early cars"? Later cars? Don't recall seeing a relay near the solenoid. There were posts about headlight relays in the past.....will see if I can find them. My early 49 P-15 has the relay inside on the fender by the voltage regulator. Quote Link to comment Share on other sites More sharing options...
busycoupe Posted May 27, 2014 Report Share Posted May 27, 2014 I have a set of fog lamps that I took off of my car several years ago to have the car painted. Now I want to re-install the lights. They were originally wired direct to a switch which attached at the lower edge of the dash, however, now I would like to wire them through a relay. I have an extra horn relay. Would it be OK to use it for the fog lamps? The lamps draw 35 watts each. At 6 volts that is just over 11 amps for the pair. I am concerned if the horn relay would work OK under continuous load. I know from working on appliances that some relays are rated for intermittent use and others are rated for continuous use. Another possibility is to find a new relay. Speedway motors sells a 6v electric fan relay that looks like it would work, but I would rather use the relay I have if it is OK. Quote Link to comment Share on other sites More sharing options...
Jerry Roberts Posted May 28, 2014 Report Share Posted May 28, 2014 I see that you haven't received any response yet so I will put in my 2 cents . I have noticed that the relays that have been listed for sale are usually listed as either horn or headlight relays . I recently bought one on ebay for my 6 volt headlights . It is a Delco Remy part number 1116789 . I am comfortable with an American made relay . Mine came without a wiring diagram and I sorted that out . If you need help with wire connections , I can help . I hooked it up before the dimmer switch so I could use only one relay . Some people use two relays and so opinions will vary . Quote Link to comment Share on other sites More sharing options...
busycoupe Posted May 28, 2014 Report Share Posted May 28, 2014 Thanks for the reply. It is interesting that your relay is listed as for either horn or headlights. I wonder if my old mopar horn relay would work for lights. Quote Link to comment Share on other sites More sharing options...
desoto1939 Posted May 28, 2014 Report Share Posted May 28, 2014 (edited) The original horn relays for our cars would have been made By Autolite. But other electrical vendors such ad P&D, Echlins, Blue Streak, Delco, Sorrenson, NApa, to name a few also made components to fit our cars. I have offered up to the members a cross reference listing so that you can track you various parts. When you look into the various catalogs you will generally find that if it is now an Autolite catalog but say is a P&D catalog they will also list the Autolite part number to help the counter person get the replacement part that their respective shop is dealing with. remember there were alot of independent part dealers and it according to which vendor gave them the best price that htye did busin ess with so you wil have a lot of cross over. If you are going for a points car then the correct manufacturer of component needs to be onthe car but if a driver no one cares. If you want a copy of the X -reference contact me. Here is the X -refernece catalog. So if you know your autolite distributor cap number then you can look under the other various manufacturers and find their respective part number for your car. This goes back to at least 38-39 and up to 1962. The cost is $15 delivered to your home and willbe on a CD. Great reference material when searching for parts at a swap meet. Rich HArtung Desoto1939@aol.com Edited May 28, 2014 by desoto1939 Quote Link to comment Share on other sites More sharing options...
lilyankee Posted February 10, 2015 Report Share Posted February 10, 2015 does anyone have a picture of the steering wheel so i can see whats inside the horn cap and the rest of it im trying to figure out if im missing anything for my horn to work cause i connect the wire to the plate it goes off and i thought that when u press the horn ring down it would go off i have a 1949 dodge wayfarer coupe thanks Quote Link to comment Share on other sites More sharing options...
BobT-47P15 Posted February 10, 2015 Author Report Share Posted February 10, 2015 The first pic is the 46-48 Plymouth Deluxe (without a horn ring).........possibly similar to the Wayfarer setup....... Second one is from the P 15 Special Deluxe with the chrome horn ring........ Quote Link to comment Share on other sites More sharing options...
BobT-47P15 Posted February 10, 2015 Author Report Share Posted February 10, 2015 Also found these wiring diagrams using Google. Model D29............click on link.............http://www.fridrichdesign.com/dodge/images/d29wire.jpg Model D30..........................................http://www.fridrichdesign.com/dodge/images/d30wire.GIF Quote Link to comment Share on other sites More sharing options...
_shel_ny Posted February 10, 2015 Report Share Posted February 10, 2015 http://p15-d24.com/topic/37982-1949-dodge-wayfarer-horn-button-and-connections/ Quote Link to comment Share on other sites More sharing options...
Eric Posted April 3, 2022 Report Share Posted April 3, 2022 On 1/21/2014 at 1:40 AM, BobT-47P15 said: I guess I just discovered something about the horn relay on these cars. The one that was on my car was a Delco HRL 4104 model. It has four connections - for "battery", "ground", "ignition", and "horn". The exact hookup of these items is shown on the wiring diagram available at the back of the P15 Service Manual. Then I looked at some similar appearing relays, I think were taken off a slightly newer model Plymouth (like 1950, 1951 or so) ..... where they mount on the firewall rather than the horn bracket up front. Model HRL 4101. They have the same hookup designations stamped on the mounting bracket. Both are 6 volts. So, it would appear you can use either model on P15 horns. The model of relay is stamped into the side of it. Our Parts Manual gives a Mopar part number for these relays, but does not tell the rest of the story.......what brand relay and what model. And, I have never found or bought a Delco manual.......which might be a rather handy thing to have. The relays look like this........... (4101 on left) (4104 on right) http://img.photobucket.com/albums/v96/BobT3/Petey%20Plymouth%201/Engine%20-%20related%20items/DSC09067.jpg And mount here on P15........ http://img.photobucket.com/albums/v96/BobT3/Petey%20Plymouth%201/Engine%20-%20related%20items/100_7578.jpg Quote Link to comment Share on other sites More sharing options...
Eric Posted April 3, 2022 Report Share Posted April 3, 2022 (edited) My question is can I use a 12 volt or modern relay with three posts as long as its at least 20amps on my Cranbrook ? or even a 6 volt with 3 posts and just ground it to the firewall ? And will it work ? and if so can someone tell me a part number that works . ... Daily driver not a show car ...want to not pay 100 for a horn relay ....one that will do the job and work with correct wiring . Please help . These part numbers are correct for my car but they are also 80 years old . I would rather use new parts for my daily driver . ....What will one of these work ? https://www.classicindustries.com/product/hr603.html https://vintageautogarage.com/horn-relay-hr106t-12-volts/ Edited April 3, 2022 by Eric Quote Link to comment Share on other sites More sharing options...
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