HT1663WB

Hey guys, on my 71 as soon as I hit the brakes the fuse blows. I replaced the interior harness a while back and I did not have any issues after the install. The switch appears to be original. I was thinking the switch might be bad?

'75

Probably not the switch, since it opens when the pedal is up and closes when you push it. I would start by pulling out both brake light bulbs and try it.

Big2Bird

If the switch is plastic, what would it short to?

Richard454

I'd disconnect the 12 pin connector for the rear harness first- otherwise you'll be chasing your tail(lights)!!!


If the fuse still blows it's a problem up front-maybe harmonica connector? New harness?

If it doesn't blow - then check your rear lights...

this-connector to rear harness-

7T1vette

Good thoughts, above.

In general, you likely have a power wire that has gotten a 'rub-thru' of the insulation and now has 'open' wire which is shorting out every time the brake pedal linkage is moved;

OR

There is a short somewhere in the power feed line (initiating at the brake light switch) which winds it's way back to the brake lights. Also, the brake switch could have failed inside to create a short every time it is actuated.

"Divide and conquer" with your ohmmeter. In other words: take the power off of the system and dispense with blowing fuses while trying to diagnose the system. Disconnect the battery and 'chase' the electrical short by testing portions of the brake light power feed wiring with your ohmmeter.