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 Trouble shooting a 56 era 12V horn systemJump to page : 1 Now viewing page 1 [50 messages per page] | View previous thread :: View next thread |
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56D500boy |
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Expert 5K+ Posts: 9900     Location: Lower Mainland BC | . While messing around with my Torqueflite (formerly Powerflite) shifter housing, I might have did something to the signal light wiring (D'oh!!) While I was fixing that, I decided to trouble shoot my horn - which was working but not consistently.  First thing was to review the wiring diagrams. I had previously posted some in this thread: http://www.forwardlook.net/forums/forums/thread-view.asp?tid=70141&... I picked the most pertinent one and annotated it so it was hopefully easier to understand vis a vis the horn system. This: That lead me to thoroughly investigate my horn relay which started with finding the diagram below and ended with this thread: http://www.forwardlook.net/forums/forums/thread-view.asp?tid=75311&... This diagram from the 56 Dodge FSM (but not in the 55-56 Plymouth FSM or the 56 Chrysler FSM) proved to be the most helpful while investigating the horn relay. Also because it clearly shows that the horn switch is a grounding switch which completes the switched 12V circuit that energizes the coil that pulls the relay points together and transfers 12V battery power directly to the horns. This: In its defence, the 56 Chrysler FSM did show up a good trouble shooting list to follow regarding horn issues. This: *************** "Three makes of horns are used. Sparton, Auto-Lite, and Jubilee. The horn circuits are tested in same manner for all three makes. The tone adjustment however, is different for each type. The horn relay is electrically connected to ignition switch and does not operate when switch is in "OFF" position. 64. TESTING HORN CIRCUITS When horns fail to blow, test circuit as follows":Touch jumper wire from Relay "SW" terminal to ground. If horn blows, it is an indication that trouble is in wire from "SW" terminal to the horn button, or in horn button contact ring. If horns do not blow, connect jumper from "B" terminal to "H" terminal. If horns operate, relay is defective. If horns do not blow, trouble is in wire to horns, in horns, or in the wire from starter relay to horn relay "B" terminal." ************** I'm now going to use that diagnostic from the 56 Chrysler FSM and suggest a similar but slightly different diagnostic: 1. With your Digital Multimeter (DMM) or analogue multimeter set to 20 V DC (or less) start by checking for power at the horn relay: a) Check at the "B" terminal for unswitched (constant) 12V power. No power at "B", there no horns. There is an issue in the wiring from the starter relay to the "B" terminal of the horn relay. Investigate and fix. b) With 12V power at the "B" terminal, carefully jumper between the "B" terminal and the "H" (= horn terminal). Horn should blow (you just bypassed the horn relay). If not, there is an issue with the wiring between the "H" terminal and the horns, or the horns themselves are defective. You might want to review this thread: http://www.forwardlook.net/forums/forums/thread-view.asp?tid=68724&... Fix that problem and check again by jumpering B to H and hear what you get. c) If the horns worked with the jumpering of B to H but not with the steering wheel horn button, now the issue might lie in the horn relay or the horn button or the wiring between the relay and the horn button. First thing now is to check for switched power at the other two (NOT B or H) terminals, the one with the bullet connector (might be labeled "G" or "S" or "SW") and the stud terminal with the 3/8" nut and the wires with the ring terminals. If you have the ignition key on and you don't have 12V power that the stud terminal you not only don't have horns, you have a car that will not be starting (or running) anytime soon. Consult the wiring diagram and rectify the problem. You must have switched power at the stud terminal if you want the horns (and the engine) to work.  Assuming that you have 12V at the stud terminal but NOT the bullet connector "G" or "S" or "SW" terminal, you have an internal horn relay failure. One or both of the wires that feed into/out of the relay energizing coil have broken. You might be able to fix it (soldering a jumper wire around the break) but if those wires are intact but there is no continuity between them (when you take the relay cover off and check with ohm setting on the DMM ), the failure is in the winding of the energizing coil: You need a new horn relay. These fine wires: And/or this coil winding: d) if you have power at the stud terminal *AND* the bullet connector "G" or "S" or "SW" terminal but the horn still does work, the issue could be the horn relay points or the wiring between the bullet connector terminal and the horn button at the steering wheel. With the ignition on, and 12 V at the bullet connector, jumper the bullet connector terminal to ground. If the horn works, it is the wiring between the bullet connector terminal and the horn button at the steering wheel. IF that jumpering does NOT work, the failure is the energizing coil and/or the points, as shown in the photo above. You can try cleaning/filing the points (with an ignition points file) or some very fine (say 200 or 400 grit) sand paper. It that helps, you still might want to seek out a new horn relay, yours is on the way out and the filing was just a temporary fix. IF you have 12V at the bullet terminal and jumpering that terminal to ground with the ignition on and the points cleaned and filed did not work, your horn relay is dead. Tot. Expired. Pining for the fjords. Time for a new one. e) if have 12V at the bullet terminal AND jumpering it to ground did give you horns, the issue is up stream. Move to Step 2. 2. Check for continuity in the wiring between the bullet terminal on the horn relay and the wire on the steering wheel that completes the circuit to the horn blowing switch. If that is difficult, you can just check for 12 V at steering wheel wire with the ignition on. If you don't have continuity between the bullet terminal and the steering wheel wire (and/or 12 V at the wire with the ignition on), you have a broken wire or something somewhere between the bullet terminal on the horn relay and the steering wheel wire. Not good news. You will have to find the break and fix it or potentially run a new wire. Neither will be fun. Good luck.  The components in the horn relay grounding circuit include: 1. The obvious wire from the bullet terminal to and up into the steering column (entering the passenger compartment from the engine bay via a rubber grommet, shared by other components). 2. A spring-loaded, spinning wheel terminal that is seated in the signal light switch mechanism. PN 1604 921 Horn Ring Contact Switch 3. A brass horn contact slip ring, with wire to horn switch. Attached to the underside of the steering wheel and held in place by the signal light cancellation ring. Either PN 1604 921 for the 55-58 cars, 1642 310 for the 56-57 cars, and/or 1819 841 for the 57-58 cars (I don't know why there are so many listings) 4. The "Horn blowing" (grounding) switch PN 1571 283. This switch gets mounted to the upper side of the steering wheel. It is two pieces held together/separated by springs that live inside three chrome plated towers on the switch. The switch is connected to the slip ring via the slip ring's wire. The idea of this spring loaded switch is you use the chrome steering wheel horn ring to squeeze the switch springs enough so that the upper switch plate (which is connected to the brass slip ring via a wire) contacts the lower switch plate that is in intimate contact with the steering wheel which is held to the steering column by a nut and, thereby, completes the ground circuit (at least in theory). The switch is held to the steering wheel via three screws the sit inside three 1450 494 plastic (non-conductive) bushings. The switch is located to the steering wheel via two small tynes on the bottom of the switch that fit into two small holes in the steering wheel. With the switch roughly in place, you add the chrome horn ring on top, then the bushings through the holes in the chrome steering wheel horn rign and down to the top of the bottom layer of the horn blowing switch. Then you line things up and apply the three screws. Might take a couple of tries to get all three lined up and the screws started. I haven't got this totally figured out but I did discover that I can over tighten those screws to the point that the steering wheel will not compress the horn switch enough to complete the grounding circuit. I backed a couple of those off and now have better horn blowing action from the chrome horn ring. So in this last section the areas that could cause a problem are: i) the wire from the bullet connector on the horn relay to the 1604 921 Horn Ring Contact Switch ii) the wiring and/or corrosion on the 1604 921 Horn Ring Contact Switch iii) corrosion and/or warpage of the the brass horn slip ring. iv) the wire from the brass slip ring to the 1571 283 horn blowing switch v) corrosion at the internal edges and/or the back of the 1571 283 horn blowing switch (cleaned the back with a Scotch Brite pad and electrical contact cleaner and the internal edges with some sandpaper, electrical contact cleaner and paper towel vi) having the screws that hold the chrome steering wheel horn blowing ring too tight. Some photos, etc. to cover these last items: Edited by 56D500boy 2021-01-25 1:00 PM (HornSwitchDiagram.jpg) (1604921HornRignContactSwitch_small.jpg) (1604921HornRignContactSwitch_2_small.jpg) (HornSlipRingContactWheel_1.jpg) (HornSlipRingContactWheel_2_showingNoticeAndLug.jpg) (DaveFsOld56DodgeSteeringWheelWithHornSlipRingSignalCancellingRingAndConnectingWireToHornSwitch.jpg) (HornSwitchDiagramPN1571283.jpg) (1571283HornSwitch_55to59_larger.jpg) (OEHornSpringLoadedGroundPadShowingTheTwoLocatingTynes_Annotated.jpg) (OE56DodgeSteeringWheelShowingHolesForTynesOnTheSpringLoadedHornGroundingPad_Annotated.jpg) (1450494HornSwitchBushings.jpg) (HornSlipRingWireFromRingToHornContactSwitch.jpg) Attachments ----------------  HornSwitchDiagram.jpg (180KB - 325 downloads) 1604921HornRignContactSwitch_small.jpg (130KB - 294 downloads) 1604921HornRignContactSwitch_2_small.jpg (59KB - 288 downloads) HornSlipRingContactWheel_1.jpg (136KB - 296 downloads) HornSlipRingContactWheel_2_showingNoticeAndLug.jpg (95KB - 306 downloads) DaveFsOld56DodgeSteeringWheelWithHornSlipRingSignalCancellingRingAndConnectingWireToHornSwitch.jpg (150KB - 301 downloads) HornSwitchDiagramPN1571283.jpg (208KB - 309 downloads) 1571283HornSwitch_55to59_larger.jpg (79KB - 303 downloads) OEHornSpringLoadedGroundPadShowingTheTwoLocatingTynes_Annotated.jpg (133KB - 311 downloads) OE56DodgeSteeringWheelShowingHolesForTynesOnTheSpringLoadedHornGroundingPad_Annotated.jpg (155KB - 303 downloads) 1450494HornSwitchBushings.jpg (64KB - 307 downloads) HornSlipRingWireFromRingToHornContactSwitch.jpg (146KB - 302 downloads) | ||
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| 56D500boy |
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Expert 5K+ Posts: 9900 Location: Lower Mainland BC | . I was under the dash (under the steering column) tidying up some of the OE wiring and my revised eBrake warning light and flasher wiring. While I was there I took some photos showing the seven (7) wires going up the steering column. One of which is the horn grounding wire from the bullet connector on the horn relay. I traced that wire to one of the two three wire connectors by the flasher and steering column and then back to the firewall grommet that is the entry point for the horn wire. | ||
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| 56D500boy |
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Expert 5K+ Posts: 9900 Location: Lower Mainland BC | . I was under the dash (under the steering column) tidying up some of the OE wiring and my revised eBrake warning light and flasher wiring. While I was there I took some photos showing the seven (7) wires going up the steering column. One of which is the horn grounding wire from the bullet connector on the horn relay. I traced that wire to one of the two three wire connectors by the flasher and steering column and then back to the firewall grommet that is the entry point for the horn wire. I think No. 7 in this photo is the Horn wire as it enters the steering column. Edited by 56D500boy 2021-01-25 11:25 PM (HornHeatFanAndTachWiresGoingThroughFireWallGrommet.jpg) Attachments ---------------- HornHeatFanAndTachWiresGoingThroughFireWallGrommet.jpg (230KB - 299 downloads) | ||
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| 56D500boy |
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Expert 5K+ Posts: 9900 Location: Lower Mainland BC | . My 56 Dodge horn has become "flaky" (intermittent) again. Not sure what the issue is. If I short out the horn relay, the horn works so not the horn per se. It must be between the steering wheel and the horn relay. Even removing the horn ring and the circular horn switch and grounding the wire from the slip ring to the steering column (mimicking the switch) does NOT consistently result in a "BLEEP". Making me a bit crazy. I might have to run a new wire from the steering wheel roller connection to the horn relay. | ||
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| Powerflite |
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Expert 5K+ Posts: 9650  Location: So. Cal | |||
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| 56D500boy |
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Expert 5K+ Posts: 9900 Location: Lower Mainland BC | Powerflite - 2022-06-06 8:33 PM Sounds like your steering column isn't grounding well. Hmm....*THAT* is an interesting thought worth pursuing. I previously thought that the steering column was continuous from steering wheel attachment point to the frame. However, having recently had a coaxial steering box pass through my possession (from the giver to the "getter"), I see now that there is a break in that continuity and that a rubber isolator is involved. So the point where the column is supported at the bottom of the dash is probably more important than I ever imagined. I've had that bracket less than tight since I installed my tachometer to allow the tach signal wire to sneek pass the steering column. Hmm..... There is my "experiment" for tomorrow.  | ||
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| 56D500boy |
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Expert 5K+ Posts: 9900 Location: Lower Mainland BC | . I recently had signal light self-cancelling failure (more on that in a separate thread). While I was in there (steering wheel off, etc.) I decided to finally (hopefully) fix my intermittent horn failure problem. Sometimes the horn would work, sometimes (most times, it would not). But then it would work. Made me crazy but not enough to actually do something about it. Until I was looking right at the problem (if only I could see it) Initially I thought that it was the wire between the slip ring on the back of the steering wheel and the round brown switch (via the bullet connector). So I removed the slip ring from the back of the steering wheel (you have to first remove the signal cancellation ring) and clipped off the old cloth covered wire and soldered in a new piece of 14 gauge stranded copper wire (complete with new bullet connector and shrink tubing (as needed)). Re-install the steering wheel and test. Nope. No change. So then I started testing the spring-loaded horn slip ring contact switch that is on the signal light switch frame. I used one of the wires from my old analogue multimeter to make the connection between the slip ring switch and ground (the steering column) - with the ignition switch on. When I grounded between the little copper contact roller and the steering column, I would get a honk/beep from the horn. But not always. (WHAT???). When I grounded between the metal (brass?) frame portion of the contact switch and the steering column I *ALWAYS* got a beep. Back to the copper roller. Nope. Sometimes, Yup. So obviously there was an issue there, between the copper wheel and the brass switch frame. I posted about this in a separate thread and the suggestions were that there was some kind of corrosion between the pin through the copper wheel and into the brass switch frame and that I should use contact cleaner and exercise (roll) the copper wheel on the pin. Which I did. Several times in succession over a 5 minute period. Spray. Rotate. Wipe. Spray. Rotate. Wipe. Repeat. Magically, that seemed to work. I finished up the signal light issue and reinstalled everything, including the chrome FULL TIME POWER STEERING cover that has been off for at least a year while I have periodically tried to fix the horn problem (thinking that it was the round brown switch or something). BOTTOMLINE: If you are having an intermittent horn failure problem, remove the steering wheel and clean and exercise the spring-loaded horn ring contact switch (PN 1604 921 which was used at least from 1955 to 1962). It might be the answer, as it was in my case. REFERENCE: http://www.forwardlook.net/forums/forums/thread-view.asp?tid=78824&... My contact switch after cleaning and exercise: (56DodgeHornSwitchWithNewWireFromSlipRingToSwitch.jpg) (56DodgeHornRingWIthFullTimePowerSteeringCoverFinallyReinstalledAfterAYearOrMore.jpg) Attachments ---------------- 56DodgeHornSwitchWithNewWireFromSlipRingToSwitch.jpg (149KB - 46 downloads) 56DodgeHornRingWIthFullTimePowerSteeringCoverFinallyReinstalledAfterAYearOrMore.jpg (146KB - 52 downloads) | ||
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| ronbo97 |
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Expert Posts: 4036 Location: Connecticut | |||
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| 56D500boy |
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Expert 5K+ Posts: 9900 Location: Lower Mainland BC | . I thought of that but when I tested my 1571 283 horn-blowing switch, I got continuity at all points of contact around the entire 360 degrees when I manually squeezed the two plates together. That said, while looking for a new 1694 921 spring loaded contact switch, I bumped into a seller on eBay who has a bunch of 55-59 Studebaker horn-blowing switches for US$16.95 (and free shipping) Buy it Now. So I bought one, I imagine that they are from the same OEM supplier as the Mopar ones but I won't know for sure until it arrives next week.  Edited by 56D500boy 2023-08-24 11:25 PM | ||
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