Every Volvo forum has a mass of threads and tutorials on this topic: 240 series tailgate wiring. (VClassics tutorial was my initial inspiration. SwedishBricks has a number of recommendations in their FAQ. The official UK Volvo Forum site has a good step-by-step. MatthewsVolvoSite, TurboBricks, and BrickBoard also have multiple threads about this.) The people who famously perfected the three-point seat belt, invented the rear-facing child seat, and were the first to make side airbags standard totally dropped the ball on the tailgate wiring of their station wagons in the 1980s and early 1990s. You may be safe in a Volvo, but your defenseless little wires are not. As we all know: you can only bend a wire so many times before it snaps. So why, I ask you, did Volvo engineers run the rear wiring harness through the tailgate hinges?
We may never know the answer to that question, but the question of how to fix the issue it pretty much universally agreed-upon by owners of 240 series Volvos the world over: reroute the wire bundles inside the car.
During the tailgate switch-out I pulled the wiring bundles through the headliner and the tailgate to the inside of the car. Yesterday I cut off all the weather-damaged bits and reconnected everything with butt connectors. (A frustrating and fiddly experience that was nowhere near as fun as I had anticipated. Every single wire had its own unique properties: some were gummy, some were brittle, some were sun-damaged, some were practically impossible to strip.)
Some folks on the Volvo boards say that without a ground back here everything runs just fine, but most agreed that they got that poltergeisty effect – random indicator lights flashing, going over a bump and having their rear wiper turn itself on, that sort of thing – and that it can also shorten the life of or outright kill the more voltage-greedy tailgate components like the washer, wiper, and demister. The original grounds (which are, of course, broken) were 12-gauge black wires that connected one half of the tailgate hinges to the other. I had to have both Matt and neighbor Lee explain grounding to me several times before I understood that what I needed to accomplish was simply a connection between the tailgate and the chassis – not a connection between the tailgate components and the chassis. This made life ever so much easier, because instead of trying to fish a wire through the narrow channel on the side edges of the tailgate I had only to drill a couple of holes to create new attachment points beside the entry and exit points of my wire bundles. I used ring connectors to attach my grounds.
Then I covered the whole lot in split wire loom tubing for the sake of looks. On TurboBricks one of the posters has uses little metal clips to hold his headliner in place (here) after what he calls his “ghetto fix”. I’ll keep my eyes peeled for something of the sort that I can clamp on there.
After all was said and done (and the battery was reconnected) I sat at the controls and flipped stuff off and on and on and off while Matt poked everything with a voltage tester. Everything is getting power . . . but nothing actually works. That’s what I’ll tackle today. Most everything should come magically back to life when I replace the fuses (half of which are missing from when we were chasing the phantom drain) and the bulbs. At worst the wiper motor may need to be replaced or rebuilt, but I’ve lived this long without one, so I don’t have strong feelings about that either way. It sure will be nice to have license plate lights again, though!
Karl has a lot of aesthetic issues to attend to, but now the only mechanical issue remaining is the reverse lights. That will be another big nasty project, and not one I can do without Matt, because it necessitates dropping the transmission to reconnect the broken wire that’s dangling out of the rear lighting cluster.