Weird things have been happening ever since I changed my tachometer cable on my 72several months ago. Fist off, every time I put the headlights on the brake light would pulsate with the handle in down position. Then I noticed with the headlight switch off and I turned the key ignition to on position the lights on the left side of the tach only would  go on. After fourth tear down and inspection of grounds leads and anything that would look suspicious of causing the problem I replaced the the original headlight switch. The brake light continued to light but not pulsate so I removed the bulb.At this point, now when I turn the
Ignition to on position and slowly raise the brake handle I hear the relay click in the center console and simultaneously the left side of the tach light would go on. There are two relays located in the center console one under the reinforcement front bracket and the other near the gear shift. It's the one located along side the gear shift that's making that clicking noise every time I raise the the brake handle with the ignition on. Can this be the culprit and if so what relay is that for?
Walter2009-08-08 08:19:19

Not sure but is that the Key warning , according to the diagram it would have a pink black wire to it, and the power for it comes off of the Stop lt  sw on the brake pedal. I am not sure how it should work but while you have the conditions as described close the door see if it changes. I shure more will sound in with help

Actually it's a tan lead from the brake switch  to the relay and from the relay back to the dash it's two pink leads. Wish I knew how to post photos on this site or links...have photos of relay and leads etc.
Thanks rraider1

 Center console. Hope this link works

http://i144.photobucket.com/albums/r189/strom19/100_0589.jpg

Sure did Crossfire 1982.... Thanks. I think I'm going to contact someone at NCRS maybe they can tell what this relay is for. Much appreciated!

I think that relay is for the seatbelt warning system, that turns on the seatbelt light on the dash. Raising the park brake will turn the light off, so that's why you're hearing the relay click. Doesn't make any sense that there would be a problem with that, if all you did was replace the tach cable, but, there's a lot of wires up there....you may have knocked a ground loose, or there may be a short.  I've read the original post several times, but I'm still not clear on all that is going on...
My feeling is there is a loose ground that is causing all of these issues....


                                                     

Thanks for that info Adams's Apple. That was also the theory  of some other motor heads I spoke with.
Well, This was the forth time I tore down that dash fascia and poked around under with no answers.
It's shop time now and I really don't care was it cost to fix....I'm done!
Thank you all again.