Brake lights work only when headlights are off

First, I noticed that my front left parking light stopped working consistantly when I turned on the headlights, but the blinker works perfectly. Then, I noticed that when I depressed the brake pedal, when the headlights were off, the right parking light would light up as well as the brake lights (stop lights). When the headlights are on, the brake lights are constantly on and if I depress the brake pedal they do not light up brighter than the taillights to show I am braking.

I have already done the basic troubleshooting and diagnostics as well as removed extra add-ons like cb, brake-force unit, ect. I currently have the center console off as well as cover where ashtray and cig lighter are in order to access those wires.

Everything seems to be okay.

Do I need to take the dashboard off and check the relays and wiring inside there?

Or any suggestions would be appreciated.

 

I can't be of much help, but it sounds like a ground somewhere. I had a similar issue with mine. The parking lights came on with the brakes. My trailer wiring convertor box was the culprit.

 

Yeah..the trailer converter was the first thing I disconnected...but the problem still remained.

I'm just going to take the dash off and check there.

 

check your bulbs,sometimes the 2 lead contacts on the bottom of the bulbs squishes out and touches the other contact

 

x2

Also check the filaments to see if any are broken. I have seen a dual filament bulb fail and cause a short between the parking light and brake light circuit. There were all kinds of crazy symptoms and no one thought to check the bulbs. Simple stuff first.

 

Have you done a corner blinker mod or any other lighting mods in the front?

Your headlights are on a completely different circuit from the parking lights (which are powered off the taillight circuit). A bulb or wiring fault in the tails would explain weird front parking light behavior, but not anything involving the headlights.

A fault (bad ground; shot bulb; short) in the rear, combined with a fault in the combination switch (light control stalk) might explain these symptoms.

 

I will definitely keep that in mind this weekend when I check inside dash...Thanks!

 

Had similar problem with a 300z I had a few years ago. Left turn signal and dash indicator would stay on (not blinking) as soon as the headlight were turned on.
Figured out AFTER I remove the turn signal stalk, ignition switch and headlight switch that the previous owner put a bulb in the that had 1 contact on the bottom, and it was supposed to have 2

WOW, just realized I responded to a 4 year old post. I'm going to go hide now.......

 

its your trailer light module shorted out, cut the wires going into it and everything will work normally again, if not reconnect them and THEN start looking elsewhere. if the module is bad use some diodes to make your own and never have to worry about it shorting out your electrical system again.

I have a mod showing you how to do that here: http://www.tacomaworld.com/forum/towing/347860-diy-easy-10-trailer-lights-plugin-fix.html