New to forum. Could use some help. I just bought a 2000 ranger 4x4. Problem with turn signal. Works fine as long as the headlights are not on, or I don't apply brakes. If that happens both of the brake lights go on then both the turn signal lights go on. This happens about twice as fast as the turn signals normally blink. As you might guess this is very confusing to anyone behind me. Obviously an electrical problem. Anyone have this problem? Any idea what cause it?
Thanks
Mike

 

I would start at the trailer light connector if you have one, these can get corroded and short out, if it isn't in the bumper look under the rear, it may have been added and is just hanging under back of truck.

At night I would press on the brakes and see if front parking lights glow a bit, meaning bad ground.
Do the same with turn signals, each side, see if opposite lights glow.

Also check Reverse lights, turn them on and check for glowing front bulbs

Turn on parking lights only and make sure all work and at the same brightness,
Then try it with head lights.

Alot, if not most, of these circuits run thru the Multifunction switch(turn signal arm), so try jiggling it and see if a fault occurs.

The 2000 lighting also uses a microprocessor and relays so you may need a replacement.
I would do as many test as you can think of and write down results.

 

Check the the operation of the turn signals (front & back) one side at a time. Next check Hazard lights operation. If they function properly, pull on park lights and repeat the above. Look for differences in turn signal brightness between sides (one dimmer than another or out of sequence front to rear). If any are found, check the bulb for broken filaments. If all check good, you'll need to check the grounds for the lights. If grounds check good, then more than likely the multifunction function switch (turn signal switch) is bad.