I'm glad things worked out for this fellow. Generally I try to give an answer that will address immediate issues as well as be completely useful for someone with a similar issue who is smart enough to use the site's search feature, or similarly be useful when Google vacuums up the information.

Here is some more insight to the running lights. 

These lights are fused, the headlamps are NOT fused. Power comes straight from the main battery cable at the solenoid to the headlamps switch. From the switch, the power goes to a fuse and then to the dash lights and the running lamps.

some cars have a switch to shut the dash lamps off.

some cars have lights in the rocker switches and above the heater control, and these are powered via a variable rheostat dimmer switch, that often fails; however a failure here will only mean those lamps will not work.

early two fuse fuse box cars have the fuse for the running lights in an in line fuse holder.

later MK IV cars with the four fuse fuse box use the fuse on the bottom to protect the running lights. Note, again, that power goes to this fuse only when the lights are switched on.

As mentioned above, the four fuse box will fail over time, and it makes sense to expect to replace it after a reasonable life cycle. It is not expensive. Also consider that the  fuse box is also a junction point to make multiple connections, and as such some simple fuse blocks at auto parts stores can not function as a replacement.

unless you fit relays to carry the actual current to the headlamps, you need to expect and plan for various failures of the lights system. This is addressed continually on this site. Some people have a hard time understanding this process.

while a meter is a great tool, you also need a test lamp. While a meter shows voltage, the test lamp may light up brightly or dimly, suggesting other issues. Check for power at the switch, at the source side and the load side of the fuse, and then at the multi bullet connector under the front slam panel. The wiring harness is pretty simple.

This situation will likely result in improving your ability to work with low voltage DC systems, which will be awesome.

I was fairly certain that the old lights were working.  Now I'm sure they were.

I unscrewed the fuse box and cleaned it up a bit.  Then I switched the green wires to the back terminal and bam!  Lights.

Thanks Dan!

Were your old lights working? Did you wire the new ones up the same? Did you ensure the new ones are properly grounded?

The next usual suspect is the fusebox itself. The fuses WILL be fine but the box itself may be not conducting. Put your multimeter across the terminals outside the fusebox, where the wires connect. You may get weak or intermittent conductivity. The reason is that the fusebox brass terminals are exposed on the back of the fusebox and eventually oxidize or corrode. The problem is that the components are riveted together, and the oxidation gets into the rivets, insulating them. You can mess about trying to fix the rivets and condductivity, but it will be a temporary fix. The solution is a new fusebox - not expensive and worth it in the long run.

As for your wiring, get the wiring diagram for your car and figure out which wires should be used for what, verify they work and aren't shorted to each other or anything else and tag or remove the ones you don't use. The added wires may be because the old wiring got damaged somewhere.

Hi all,

I have an '87 Mini and I purchased (received as a Christmas gift) new tail lights.  After installing them, and driving around in the evening, a neighbor notified me that the tail lights weren't on.  All I did was replace them and I have no idea why they aren't working.  Here's what I've checked so far. 

I've taken a multimeter to all the fuses and they seem fine.

I've pulled out the headlamp switch and it has a dark blue, brown and something else hacked together.  When I flip the switch, the head lights and tach light up.  No tail lights.

The tail light wiring is a mess and there's all kinds of extra wires that go nowhere.  There's a couple black wires, a yellow/blue set and a green/red set that have strange ends that seem like they should plug into something.

The wires that get plugged into the lights are red/green (2 sets), green/brown and green/purple.  There is also a black ground wire that is plugged into the back of the light itself.

This all seems to make sense from my research.  I just don't know where to go from here.  Any help would be appreciated.  Thanks!

Jamey