[67Twistytee]

My horns stopped working and I’m trying to troubleshoot. I ran a jumper wire from the battery and they both sounded, so I suspect the relay is faulty.

Looks like I have a 3-prong relay which would match a ‘66 Tempest rather than the 4-prong “Little Fuse” repops I see available from online vendors. My wiring is all original and this car was a December ‘66 build. Can anyone help me confirm which relay is correct?

Untitled by Twistytee, on Flickr

Untitled by Twistytee, on Flickr

Untitled by Twistytee, on Flickr

[67Twistytee]

It’s stamped “MADE IN USA” on the top, but otherwise no other markings.

[madeuce50]

1965 to 1967 GTO Lemans Tempest used the same horn relay, GM 1377993 for both 6 and 8 Cyl cars per the 1966 and 1969 parts books. the short 4th "leg" on the original and reproduction Littel Fuse unit is not a terminal. So yes all 65-67 Pontiac A-bodys have 3 connections like your harness. The relay you have looks like a vintage parts store replacement.

[67Twistytee]

Ok - thanks. That’s what I thought and assumed the 3 prong one i had on there was old but aftermarket. The replacement Littlefuse wasn’t working at first but it turned out to be a ground problem. Got both horns working again which is always a plus.

[Andre]

I see the plug is 2 prong with a block off portion that coindes with the 3rd prong of the the relay or am I not looking at it correctly.

What happens to third prong?

[Greg Reid]

I'm guessing that the two prongs on the relay must line up with the single socket on the plug, then the loose, single plug that's dangling goes to leftover relay prong?
By the way, I like to verify things before I buy a new part. Make sure that when you push the horn button, you are getting 12v to whichever socket plugs into the coil of the relay. If it's getting there, it will pretty much prove that the relay isn't working.