There are a lot of posts about harness "rot" caused by poor quality wiring insulation in 1980 to 1986 240s, but another significant problem is engine harness chafing in "hidden" areas which can be easily fixed to avoid breakdowns. The harness is OK but the support/restraints for the harness vary from poor to awful. Some chafing/problem spots in my 1979 240 K-Jetronic engine harness (and probably for LH Jetronic harness too):
1. Harness cable-tied to engine lifting eye (connected to inlet manifold studs) on cylinder #4. Chafed thru sleeving to expose wires. Cut off cable tie & chafed sleeving and replace with split sleeving - no need for tie(s) here since this spot has a lot of movement - especially with old motor mounts.
2. Sharp edge of engine adjacent to distributor - chafed thru sleeving on cable from alternator (that goes under front crankshaft pulley). Needs some split sleeving added.
3. Volvo OEM cable supports - 2 bits of thin metal without any rubber - that hold cable from alternator as it goes under the front crankshaft pulley. These chewed thru sleeving into cables. Dump OEM supports and replace with aftermarket cable supports - thicker metal with rubber wrapped around the metal.
4. Wire to the temperature sender (under inlet manifold - cylinder #3) has no sleeving so chafes against engine. Wrap with spiral wrap sleeving will fix.
5. "Ignition harness" - cable from distributor that runs under front crankshaft pulley, then over alternator and across to transistorized ignition module. Problem as for item #3 above, but this also chafes on top of alternator, and is subject to a lot of flexing at the connector on the fender - as it has to take engine movement. So much so that all flexing was taken by the copper wires as the plastic insulation had fractured where it enters the injection molded connector. Fix by trashing this cable and taking a new cable back around the engine along the firewall. Kept 1/2 inch of original wire at the connectors and soldered in new cable. Cover joins with heatshrink tubing. Keep this cable well away from high-voltage ignition wires - no interference needed!

I caught these problems during mechanical maintenance, prior to them causing electrical problems, but left unfixed they would have soon caused plenty of grief.

I think Volvo harness poor support and poor connector quality are an Achilles Heel for this car. My wifes 1987 Toyota has much better harness sleeving, support and connectors. Connectors near the Toyota engine are hermetically sealed, not open-to-the-environment spade connectors as on Volvo.

sutherml @ Adelaide, Australia
1979 244GL @ 521,000 km