headlights dim down until off need help

It sound like you battery is going flat ?

could be ... bad connections bad genny / alternator bad regulator bad battery

or ... have you added any other electrical equipment ?

like ..

electric heater big ass stereo system extra driving lights etc etc ?

Rich

Will it do that on either High or Low beams? If so, my vote is the Ignition switch. On '72 cars, all power for Headlights goes thru that dinky Ignition switch.

When the switch finally burns up, you won't be able to start it anymore either.

Oh, here's a good test. After the lights have dimmed down, try the wipers. If they don't work either, it's def the Ign sw.

This is what the circuit looks like (diagram from my web site):

I would simply snip the Blk/Yell lead off at the Ign sw and reqire it to battery + on the fuse block.

Speedy Jim

I have only changed the amps to a larger size amp so more power goes to it.

tricky wrote:

In that case, the dimmer relay is suspect. To prove it, jumper Blk/Wh on the relay to Yell (56 to 56b)

Jim

Hmmmmmm. Pull the relay out and identify those terminals (56, 56b) on the socket. Should be marked on the side of the relay or the base. Stick bare copper wire in those 2 holes to form a "jumper".

They're not terribly expensive:

Jim

One wire to connect the two. Jim

Connect 56 and 56B together with one piece of wire (technically known as a "jumper")