88 240 not charging, checked all i can think of

[sebrenite]

I had the same issue, but not sure if my 1990 740 problem will apply to you. I had a short on the instrument panel and that is where the 12V for the field coil comes from. The instrument panel is known for bad solder joints.

Again, may not relate at all, but I thought I'd share.

[eskorch]

Try the belt tension. It will turn but not fast enough. My tensioner was stripped.

[TunaNugget]

I'd also double-check the belts. I tried getting away with a single belt once (my 90 takes two to the alternator) and had the same charging problem.

[jbasford]

I had all these issues and went through all the checks and bypass wires. I did get it figured out. Sounds stupid, but it was the Belts slipping.
They look like they are turning and even when I cranked them down they were apparently slipping. I would have never thought that was the issue looing at it, but new quality belts did the trick
A trick to check if slipping is to try to turn the alternator pulley by hand with the engine off. if the belts are grabbing the engineer main crank and fan pulley will want move before the alternator pulley spins on the belt.

I had asset of belts from the mass auto parts store they are junk compared to factory Volvo.

[lummert]

Some of the aftermarket belts are 11 mm wide instead of 11.9 mm.