Skip to main content

 I know relays are a confusing topic to some people. Like many things though, once clearly explained their complexity is removed and they are easily understood.

So, Hot Rod  magazine, in their March 2020 issue, devoted four pages to the “right way” to build relays. First off, what they really meant was the right way to crimp a Molex connector - which is what three of the four pages were devoted to. 

 But the first page was devoted to relay wiring and they included a photo of a 5-pin relay imprinted with a its pictorial wiring diagram,  plus a little box outlining the duties of each of the five terminals.

 Nowhere in the text of the article was there any mention of “normally open” and “normally closed” contacts. 

  Thanks to this article there will be untold car guys scratching their heads wondering why their relay wiring project isn’t working the way they thought it would. “  I did it just like the article said to do it ??”

 Can it be that the entire editorial staff at Hot Rod Magazine has no idea what a standard automotive five pin relay really does???



Hint - 87 & 87a




Images (1)
  • C318481F-F668-4447-A0A9-F7E49F725A8D
Original Post

A lot of articles in that and similar magazine just continue to amaze me. In your attachment note  01  talks about using 87a for connecting to an extra horn. That would work out great, if you wanted the second horn on all the time... When you hit the horn button the other horn comes on and the second horn goes quiet. I suppose you could wire in a second relay to 87a of  the first relay which will then be activated when the horn button is not pushed, with the second horn connected to 87a...  It takes me less than 20 mins to read those magazines, they do have nice pictures sometimes. No wonder Car Craft went under.

Last edited by bdud

 My comments were built around a standard relay; the design that will be found in most automotive applications. I imagine there are specific purpose variants in the relay world that I haven’t seen. 

 Staying with the article, the relay with its pictorial imprinted on it is clearly a standard 87 and 87a relay, each respectively being normally open and normally closed. 

 The author should have just stuck to a tutorial on crimping connectors. By attempting to gloss over relay function,  his inaccuracies will undoubtably cause more problems than solutions. 


Add Reply

Link copied to your clipboard.