Howdy,
86 volvo 240 stopped charging. Alternator and battery tested good. What I gather is the ?exciter wire? is burnt like there was a short somewhere. I'm going to replace it but I'm having trouble following it through the engine bay. Not really sure why it shorted so I want to check the entirety of it. Where is it supposed to end up? Somewhere on the firewall I'm assuming it goes to the ignition right?
Thanks for any tips.
EZ

 

the D+ wire goes to the intrument panel, through the batt/alt light, and to the ignition key.

On a 87/88 240 (I don't have a 1986 greenbook), starting at the ignition switch pin 15, a red/black wire goes to pin 3 of connector '233' (the 3 pin connector on the back of the speedometer), that goes to the battery/alt bulb, then a red wire goes from pin 11 of connector '31' (the full circle connector on the back of the instrument panel) to pin 3 of a 2x4 pin block connector near the center of the firewall, and a red wire from that pin to the alternator D+ (exciter) terminal.

86 is in the 'biodegradable wiring' era, many of these cars have insulation thats flaking off inside the black tubular wire harness sheaths.

anyways, I'd locate that block connector, unplug it, and see if there's voltage on pin 3 when you turn on the ignition. if there isn't, then I'd check the alt/batt bulb in the instrument panel.

 

Thanks for the tips. This our third or 4th 240 so I'm unfortunately familiar with bio degradable wire sheathes. I'm sure it seemed like a good idea at the time, but 20 - 30 years later I sure do hate the bastards that designed it! Was running low on daylight so I replaced what I could see; about 2 feet till about the distributor. Seemed like it was mostly burnt right near the alt. It's running for now but I think I'll go back and do the rest this weekend for peace of mind.

 

re: biodegradable wiring... Volvo adopted 'green' insulation circa 1981 or 82, and by 1987 realized it was going bad, late 87 and most 88 cars are an improved insulation.

Mercedes, hahahaha, they made the same mistake TEN YEARS LATER, in 1992 or 1993 they switched to eco-crud wiring, and fixed it in 97, so 1998+ harnesses are good. At least Mercedes still sells replacement harnesses for all their cars, Volvo *used* to but Ford stopped that silly wasteful practice.

 

Hi,

On all three of my 240s, both the oil light wire and the exciter wires burned up because they are routed under the engine where they are vulnerable to weather and engine heat. I slit the harness that comes up near the distributor and found those wires (by gently tugging on the burned wires, then pulling the burned wires through to the top of the engine) then cut off the bad portions and spliced in new teflon insulated wire and re-routed it around the firewall to the other side of the engine where they connect. No more worries.....