Brake light dimming

[gip63]

          When i push the brake pedal it causes all the lights to dim, is that normal on these old cars?   Is there a solution?   Thanks

[DynoDave]

Sort of hard to say for sure, but can be normal to a degree. These cars had small alternators by today's standards. My '70 Duster with no power equipment only had a 36A alternator. And that's max output. At idle, you might get 10a or so. That now has to be divided between all the lights, blower motor, an aftermarket stereo, etc. So yes, the headlamps could get dim, and even dimmer as the turn signals flashed, the brake lamps illuminated, or the stereo thumped. With a load, you may actually be draining the battery for the few moments you are stopped at a traffic light.

Now if it's really excessive, that can well indicate an issue, like a failure in the trio diode, bad regulator, bad ground, slipping belt, etc. You would just have to know the specs of your alternator, and have it's output checked, IMO.

[gip63]

       I was having lots of trouble when i first got the car, it had a 45 amp alternator.  Later i discovered they made a 78 amp and i got it and it helped a lot.  Still though when i hit brakes it dims the system down but not as bad.  

[Nacho-RT74]

the deal is the pooor output while iddling... and also of course the 40+ years of old terminals dirty and rusted

[DynoDave]

Let's not forget the bulkhead connector, while we're checking for electrical issues. Do some reading here...

ALLPAR

MAD

Also, if you upgraded your output by 60 or more %, you may need to upgrade the wiring to support that.

[Nacho-RT74]

And:

Bulkhead bypass working ammeter

[draftingmonkey]

Use electrical contact cleaner (I prefer Caig) to clean the plugs. Disconnect, spray it down and work the plug, use a brush where possible. Do not forget to pull the fuse box and clean the connectors on the back side and even the fuse clips.

As a side note my A/C quit working at home, compressor would not start. Hosed down the contacts on the compressor unit with contact cleaner and it has worked great since. So before calling an HVAC repair person if your A/C unit doesn't want to work, try cleaning the contacts. It is amazing how often dirty contacts are the culprit and a repair person will want to replace the contacts where not always needed.