Stumped about '90 740 Wagon tail lights

[cornholio42]

I am stumped. My rear running or night lights and brake lights do not work. Everything was fine the last I drove this vehicle about 6 months ago.

What does work:
- Middle window light and plate lights turn on with the headlights.
- Everything on the front of the car works fine.
- Rear signal and backup lights work fine.

So far I have:
- Tested all the bulbs, they work and are all the correct type of bulb that should be used.
- Pulled 6 bulb relays from our local pull a part and swapped them in an out, no luck.
- Metered a solid 12v coming to both rear panels. Metered 12v running through the panel.
- Replaced the brake switch with a known working one.

The only change I have found is two of the 6 bulb relays (the two different in color or size from the taller red one in my wagon) make the front corner markers light up when I hit the brake. Odd, but I guess I can assume the brake switch is somewhat working? Maybe I can drive this thing in revers to work instead?

Not sure where to go from here. I am thinking maybe the relay box connectors or loose or something, but I am not keen on ripping that all out just yet.

Any ideas? Thanks.

EDIT: Crud, wrong forum. Could a mod bump this to the right section? =/

[rspi]

You might want to move this to the 740 section.

[billofdurham]

From which models did the failure units come? Was there a red failure unit among the 6? It was fitted to the 240, 740 and 940. In theory the other failure units shouldn't fit.

Bill.

[ed7]

Sounds like a ground problem. Check all ground connections and clean/tighten them.
Ed