70 Cuda Horns not working

Posted By: CudaRSSS

70 Cuda Horns not working - 01/02/13 03:23 AM

New to the site, am finishing up a restoration on our Cuda. Correct restored factory horns added, tested and work. Replaced horn relay, the kind that connect to fuse block. Wires look good from firewall to horns. Wire and horn ring look good and intact. Horn relay does not click when I push horn, no power to wires going to horns. Just not sure what problem could be, any help is appreciated.

Posted By: screamindriver

Re: 70 Cuda Horns not working - 01/02/13 03:35 AM

Hello and welcome to the board !!!

The new horn relay not clicking means it's not energizing...Do you have the schematic for the horn circuit ??? Here's a link to the 70 plymouth factory service manual... link Looking good and testing good are always two different things...You'll have to start checking the circuit beginning with simply grounding the horn wire in the column and go from there...Do you have the column grounding wire in place ???

Posted By: CudaRSSS

Re: 70 Cuda Horns not working - 01/05/13 01:24 AM

Good question, not sure, I found the black horn wire that attached to the clip near the ring under the cap, that it? Or is there something else?. Thank you for the information and link, I hope to dig back into it soon.

Dennis

Posted By: RapidRobert

Re: 70 Cuda Horns not working - 01/05/13 01:51 AM

Quote:

I found the black horn wire that attached to the clip near the ring under the cap, that it?

Yes. There's 3 terminals on the horn relay on the firewall. www.mymopar.com will have the colors for you. (1) One terminal should be hot all the time (see if it is). (2) Jump fire to the second wire that goes forward to the horns & they will honk unless that circuit has an open or both horns are bad (not likely) or both horns have lost their ground (not likely). (3) the third wire is the one mentioned & goes back to the horn button so jump that terminal to ground & see if it honks & if so check each connection from that terminal on the relay back to the horn button (bulkhead/column harness/horn button itself). Seperately the column is grounded to the frame with a length of black wire several inches long with eyelet terminals on each end & is used on the bracket that bolts the column up to the dash.

Posted By: NachoRT74

Re: 70 Cuda Horns not working - 01/05/13 04:41 AM

you can unplug the turning switch harness and ground the black wire on plug. Should get horns. If you do, problem is at horn switch or column inside... if not, problem is somewhere between plug and relay... or relay itsef

Posted By: CudaRSSS

Re: 70 Cuda Horns not working - 01/10/13 01:54 AM

I did some testing. I ran power to #3 on the picture and the relay clicks when I press the horn button. It also causes lights to dim. I am thinking ground ?
I ran ground to # 1 and # 4, both times the relay would buzz. When I run ground to # 2 it sparks, but strange I do not get power when testing this point.

I tested the horns again and they both work. I could not find a ground wire on the column. I also have a 71 Challenger, I looked for a ground wire on the column but could not find one there. Those horns work perfectly. I also attach a couple pics to show you what you are helping me with. Its so close to being done.

I appreciate any suggestions or thoughts.

Dennis

Posted By: Jim_Lusk

Re: 70 Cuda Horns not working - 01/10/13 03:29 AM

It's a very simple circuit, but you need to understand what it is doing. The relay is in place to convert a switched ground to a switched 12v. This is done by the switch (horn button) providing ground to the relay which should always have 12v on the input side.

The column must be grounded. Some cars may need the ground wire while others, due to worn paint, etc. can provide the ground through the mounting points. Remove the horn button and check for continuity to the relay. Also check the ground on the column.

You also need 12v input to the relay. That is easy to check with a meter, too.