Here is my history of the horn and back up lights. The car came without a cancel cam and retaining ring and no reverse lights. I put in a bad review on Google about my experience with the dealership that I purchased from. They contacted me immediately. They didn't return my calls prior. With an extensive conversation with the mechanic, they sent me a new reverse switch, cancel cam,retaining ring and horn relay. I have reverse lights, no horn. More conversation with the mechanic. The brand new horns that were in the car were no good and the turn signal switch where the brass spring loaded button in was shot. It did not have enough spring in it anymore to hit the cancel cam. Horns were easy to replace, turn signal switch was a lot of fun. It didn't line up to the old harness. I had to cut at the gap near center and shave the ends to get it to go in. After a lot of shaving it was in. Put everything back together and tooted my horn. What a wonderful sound. Then I started my car and put it in neutral to check my turn signals, the horn started honking. We are at a loss as of why. Any ideas?

 

You need the jumper adapter harness. I had same problem. I wish I could remember exactly! Seems like there are 2 switches listed for my 71 Cutlass. I bought the cheaper one (which I bet you have). Got steering column all back together and went to connect wire and wouldn't fit. Modified it and checked it out and yes, horn sounded when turn signal on-HUH? So went back to parts store and bought other switch that had adapter harness. ( Standard brand switches). Meanwhile took 1st switch out. When 2nd switch came I found that switches were identical- I wouldn't have had to remove 1st replacement switch- so don't do that. Just order the switch w/ adapter and leave your switch in. (unless you ruined the connector?) Use the adapter- (I didn't like doing that seems like a cobble job). Anyway it all works now. I just kept the brand new 1st switch in my extra parts stash.. Good luck! Let us know how it goes. Look on Rockauto and see the 2 deferent switches- sz they both fit which is wrong....

 

"Dealership" hahahahahaha!

Get a factory service manual. The horn is ground trigger and the turn signals are positive.

 

Wondering what happened???