I think I found the culprit for the brake warning light turning on in this '83 240 turbo. While attempting a flush using a power bleeder, I couldn't get fluid out the right rear caliper bleed valve. All others bled fine. I knew the line from the rear brake hose to the caliper was OK because I had flushed it to make sure the path was clear before installing new brake hoses. Going upstream, I found that there was fluid getting to the proportioning valve/pressure regulating valve going to the right rear caliper, but nothing coming out of the valve on the hose side. I found a fix in the Brickboard archives written by Steve Seekins, but this method can damage the junction box (I just replaced it, so don't want to put it at risk). Any suggestions other than replacing the proportioning valve? Also, vendors such as IPD, fcpgroton, alloemvolvoparts don't list this part. Anyone know who sells it, apart from the dealer? Thanks for any info.