Having trouble with headlight and tail light

What did you replace the headlight bulbs with?
I you changed to L.E,D. you have to make sure that the bulbs are the right way round in the socket.
The L.E.D. bulbs only work if the ground side is grounded.
If the L.E.E.s are not working turn them in the socket and try again.
The other bulbs depend on the grounding of the main bulbs.

The brake/turn lights are on another circuit, not on the same as the main lights..

Regards
Geoff..

could be a faulty globe too

HI Matt,
Your issue sounds like a fault, most likely in the rear lights. Current is feeding from the brake light circuit, into the running light circuit. The most common causes are a bulb filament broken and touching the running light circuit, and loss of ground.
observe the rear lights closely and you should get a clue as to which light is failing....but if not, just pick one....
I would run a temporary ground and test again, if no results, pull the brake light bulbs...
Transient current is often difficult to wrap your mind around, until you understand what can happen.
Doc

Your right rear turn signal bulb is blown.Replace the bulb and the fast blinking will stop.

Me too, same problem here.

check for relay for that light and possible ground wire problem

I had this same problem i cleaned contacts that the bulb goes in and put dialectic greese on them.Also one bulb I think on passenger side brake light.one element shorted.Replace bulb and you should be all set.Dont ask me why.Must be bad design.

sounds like a ground problem or malfunctioning signal switch

bulb. or fuse

i was having a similar problem with my 2000 SL. when the taillights would go, so would the cruise control. and through many bulb and fuse replacements, i finally went into a saturn dealership and they did a recall campaign on it. they did their thing and i havnt had any problems since. FREE!