I recently replaced the tach cable on my 72 and after I put things back together again I noticed I no longer had an emergency brake light when I pulled up on the brake handle. As I continued to look for the gremlin that was causing this I pulled on the head light switch and noticed the brake light came on for a few seconds then it went off and began to pulsate on and off until I pushed the lights off. It only happens when I put the lights on but all the other dash lights remain normal and do not pulsate or flicker. I have spent hours inspecting wires under the dash and looking for anything out of place that might be the cause of this problem but so far I came up with zero. If anyone else has experienced this problem I would really appreciate your input.

My first guess is always a loose ground.  And the pulsing could be feeding through the headlight circuit breaker, which trips and resets.  I am afraid there really isn't a quick test to find out where, but you can try running a temporary ground from the back of the instrument cluster to see if it changes the symptoms.

Larry

Thanks Larry, I'll give that a try and see what happens. I know I disturbed something when I replaced that tach cable because everything was fine up until then.    Fred 

I totally agree with Larry...a bad ground somewhere. This is  not unusual after working behind the dash. I always dread working back there because more times than not it creates worse problems. I think using a wire to make a temporary ground will help. Keep us posted.

Scott
ranger32009-03-03 18:05:10

Scott, Thanks for your input also. Hopefully tomorrow I will give it a try if my back holds up..LOL

Scott, Just a quick note on that problem I was having with My brake light pulsating.  After creating a good ground connection and connecting the other end to the rear of the Instruments Speedo and Tach  in several places the brake light continued to pulsate. Well I guess the Gremlin won this fight but at least I wont be hassled by hm anymore.... I removed the brake light bulb.... It's now fixed... I appreciate your input and Larrys as well.   Many Thanks,    Fred 

Larry, Just a quick note on that problem I was having with My brake light pulsating.  After creating a good ground connection and connecting the other end to the rear of the Instruments Speedo and Tach  in several places the brake light continued to pulsate. Well I guess the Gremlin won this fight but at least I wont be hassled by hm anymore.... I removed the brake light bulb.... It's now fixed... I appreciate your input and Scotts as well.   Many Thanks,    Fred