Freinds:

First thanks again for all your previous help. I searched the boards to see if this topic had been covered but did not find anything quite on the point.

86 240 volvo. Ordered a set of replacement tail lamp clusters (complete) from aftermarket supplier. They look great, only problem is the secondary brake lamp (the large bulb at the outside bottom of the cluster) won't come on. The circuit looks complete, and the bulb seems solid.
The lamp I am referring too is the one at the bottom right of this pic, with the white screw cap base.

Both brake lamp works fine on other light (which is on passenger side) and fuses are solid.

Wondering if there is a better way to diagnose the issue, or any tricks to making circuit contact that would get this lamp working.

 

I'm playing dumb here, our 244 is out in the driveway and I'm too lazy to get the keys and remember which is what, but there's a 'Fog' warning light in the tail, only the left side is wired, and its controlled by a dashboard switch. its as bright as the brake lamp bulb. you're not confusing this, are you?

to diagnose that sort of electrical problem, you need a digital multimeter. car shut off, look for continuity between ground elsewhere and the ground on that socket's contacts, ditto look for continuity between the removable bulb socket (you can poke your MM lead through the gaps in the back) and the flexiboard. I dug up my Bentley book but the schematics in there are almost unreadable, so I dunno what color wire is which signal on the connector, brakes *might* be yellow ?