Just for the archives. I would seriously advise not randomly soldering pushbutton controllers after model year 1986 (including 86). From personal experience I can tell you there are multiple electronic components after 85 controllers that don't like getting hot. If you trust your diagnostics and are sure its junk, finish it off, but the electronic controllers of 86 on cars are very seldom fixed with resoldering. I'm guessing your chances of killing a controller are greater than fixing one with random solder on the electronic controllers. There are no electronics in the PBC before 86, its just a switch board.

As RPM55 stated the circuit is controlled on the ground side and most of the pertinet circuitry is easily exposed on the three wire connector next to the brake booster. Go for the yellow wire to view all that matters from the PBC. It sends a 1v-6v signal. If not there deal with the PBC. If the voltage is there and the red wire has power, you are looking at a blower or blower controller problem.

Just as doctors, proper technicians should "do no harm".

__________________
Steve Brotherton
Continental Imports
Gainesville FL
Bosch Master, ASE Master, L1
33 years MB technician