Ok, so I bought the 240 Wagon for $1200. Drove it home 200 miles. Nice! My brother was following me back home. Around dusk I switched the lights on. As it was near dark, my brother called me on the cell phone and told me I had no tail lights. We pulled over and I mentioned that the headlight selector was stuck in the high beam mode. We fooled with it a little, and found out when headlights are set on low beam, the tail lights work. All directionals, brake lights and backup lights work too. But when you switch the high beams on, all back lights go out. All fuses look good, no other issues with the car. I know something is wired wrong somewhere. So where do I start looking?

 

Yeah, you got a problem somewhere... Nothing standard comes to mind. '87s are very prone to wiring disintegration. Hope you looked for telltale signs before you bought.

 

Bulb integrity sensor under steering column.....or that light relay by the battery...the silver one.......they are related to the high low beams....can't think of anything else...

given that the back tail light harness is ok....specially under the back door hinges where the wiring is squeezed through...you got to take off the door to inspect....easy with two people...if you do take off the back door/gate inside panel that is covering the door frame....in order to take it off the inside handle you must remove the entire panel and spin it in order to align the plastic cover behind the handle and wiggle through...

 

I think I would sit down with the 1987 greenbook wiring diagrams, and go through the car with a volt meter or test light checking various wires and connectors for juice in the various switch states until something pops out that doesn't jive with the wiring diagram, and go backwards from there til you find the fault.

your parking lights should work when the light switch is in the middle position even if the car is switched off. if they don't, something is very funky.

way hard to do this over a forum, but for a start, here's the parking lights wiring...

battery + goes through the postive junction (on a 240, this is on the left fender, its a little black flat box with a pile of red wires) to the in side of fuses 6-7 (which are bridged) and from 7, a green-red wire goes to the headlight switch pin 30. this should be ALWAYS ON, and is unfused (the fuse 6-7 thing was just used as a convenient terminal strip).

headlight switch pin 58 is on when the lights are in park, and a white wire goes to fuse 15 which is bridged to fuse 16.
when the headlight switch is ON, pin 56 is powered only if the ignition is on., this goes to a 'main relay', which connects always-on power to the same fuses 15,16. the net effect here is that fuses 15&16 are powered if either the light switch is in 'parking' OR (the ignition is On or Accessory AND the light switch is in 'headlight'). I note that 1986 cars didn't have this relay in the circuit.

other side of fuse 15 has 3 white wires, one goes to the front left corner light, one goes to the license plate lights, and the last goes to the bulb failure 'beercan' pin 15. beercan pin 14 is a red goes to the left tail parking light.

other side of pin 16 has 2 green wires, one goes to the front right corner light, the other goes to beercan pin 14. beercan pin 12 is a brown wire to the right tail light.

headlight power is completely different, and doesn't even go through ANY of those circuits.

the fact that your high beams seem to enable/disable the tail lights makes me wonder if there isn't a floating ground somewhere, such that the current isn't going the way it should, this would also make the bulbs dimmer than they should be.

 

Today I noticed someone has spliced into the wiring on he headlights and front parking lights. Also wiring through the tailgate hinges shows bare wires rubbing. I think someone ran new wires to the backlights but in a shoddy way. Ordered the Vovo green book of electrical diagrams today off of Ebay. Have one more question. Next to the headlight relay is a newer style 25 amp fuse in a single holder. wired to something, have not traced[IMG]http://it yet. I assume this is a non stock add on. Over all I love the car. Here is a picture taken Friday when I bought it.

 

well right behind the battery on a 240 is a fuse holder with a 25A blade fuse that powers the whole fuel injection system... this comes directly off the battery. the original fuse holders get mighty funky over 20 years, and people tend to replace them with things like marine fuse holders... one side is directly on the battery + terminal, and the other side goes into the wiring harness that disappears down towards the intake side of the engine.