Hi, quick question for you guys out there cause im loosing it!

My 66 - i just installed a new dash harness, engine harness etc - basically every harness available. (Note: dummy lights not guages, column automatic).

When i drive down the road -the lights get bright then dim - dramatically.

Why? What do i check for etc??

thanks
eric

When I installed all new harnesses on my 66 SS, everything worked but I had no dash lights. The light on the heater/AC controls was lit, and the idiot lights worked, but no other inst lights. It turned out the instrument panel was not grounded adequately. Using an existing screw, I attached a 4 inch wire (with a star washer) to the corner of the metal instrument panel backing plate. I connected this wire to the body at the ebrake pedal mount using a self threading screw and a star washer. Problem solved, dash lights bright and constant.

My guess is you have a weak path to ground on your instrument panel and this is causing your fluctuating lights. If you do indeed have a weak ground, when you connect a grounded wire to the inst panel, the lights should glow brightly.

One other thing. Your instrument light control on your headlight switch could be dirty or corroded. It is possible to clean this up simply by turning the headlight switch knob back and forth through its entire travel several times. This will clean up the contact between the wiper and resistor in the switch. Hope this helps.