The emphasis in this post is doing simple, quick & low cost maintenance to the engine compartment electrical cabling to avoid breakdowns.

Part 1 at(http://www.brickboard.com/RWD/volvo/1310083/220/240/260/280/240_wiring_engine_harness_maintenance_avoid_breakdowns_chafing_fix_cable.html) details "hidden" chafing of the harness and how to fix.

Part 2 adds more maintenance to avoid vibration induced fracture.

Problem: The alternator ground wire (blue or black) from the alternator chassis to the alternator engine mount is subject to alternator vibration/movement and tends to fracture at the eyelet on the alternator. This is because the wire is short (4 inch) plus its insulation hardens with oil & heat so all the flexing is then taken entirely by the ends of the wire. Then the alternator end "Utilux style" eyelet has a weak/thin point where the crimping meets the eyelet body, so fractures at this point. Since the alternator then becomes "ungrounded" the AMP idiot light does not function so there is no warning of a problem until your car stops - miles from anywhere.

Check & Fix: Examine the alternator ground wire insulation & if it has a crack(s) then its embrittled. Flex the wire and if stiff or cracks it has also embrittled. If embrittled remove the wire and can re-use it. Put wire on some flat concrete and belt it over entire length of insulation with a hammer. This cracks and allows you to peel off the embrittled insulation. Doesn't matter that wire is now squashed to an oval shape - it is now free to flex. Slide some sheathing or heatshrink over the small eyelet to cover the entire wire if wanted but wire can be left uncovered since there nothing for it to short to at the bottom of the alternator.
If the eyelet looks stressed/damaged chop it off and replace with a robust "Narva style" eyelet which has no "thin point". To get a good connection with new eyelet before crimping/soldering, put propane torch on cut end to burn off oil & verdigris. Then spread heated strands and clean up with emery paper.