240 Bio-degradable wiring, not greatThis article discusses the problem whereby Volvo made a formal policy decision to use biodegradable plastic insulation for the wiring harness of cars made in the early 1980s time-frame, such as my 1981 Volvo Turbo, which now has a disintegrating wiring harness. So instead of there being a little bit of extra plastic in the landfill, there might soon be an entire car. Not the best policy decision ... and yes, it's bad. Here's a photo of the positive wiring leading to the side indicator light ... there isn't much insulation left.
So, if you buy used parts from that era, best assume the positive wiring is iffy and replace it with good stuff.