I have a 1985 244 GL with the B230F engine, 148K miles. The car sat outside for 5 years before I rescued it and returned it to running condition. Recently the engine became hard to start, cold, which I troubleshot to a bad coolant temperature sensor. When I got ready to change the sensor, I noticed I had several wires with the insulation burned off. It occurred to me that this was not an optimal situation, so I tracked one of the wires, the yellow wire that goes to the coolant gauge sending unit, back to a gray connector just in front of the firewall. After trying to sort out the wires, I postponed the job until I had several hours to devote to the repair. When I started the car, the temp gauge went all the way to the stop, not surprising me, but the oil pressure light also came on. I checked the oil level, which was fine, then tracked down the sending unit - the insulation was burned off that wire, too. I tried to buy a replacement harness for my four crispy wires and discovered that Volvo doesn't carry a replacement (they have an engine wiring harness for $345, but it doesn't have the engine side connector or wires), nor have I had any luck with salvage yards.
This morning, I attempted to replace the four wires. I started at the gray connector. On the "car" side of the connector, there are five male pins, connected to yellow, yellow/blue, red/green, red,and black wires. On the "engine" side of the connector, there are only four female pins, connected to the yellow, yellow/blue, red and black wires, all of which have the insulation burned off outside the main wiring harness. The red/green wire that terminates at the "car" side of the connector does not apparently go to anything important, as the car runs fine when warm. I began rooting around in the wiring harness and found that the only wire I can track is the yellow temp guage sending unit wire. The Haynes book does not have a wiring diagram that depicts my car, and I hesitate to guess wrong. Does anyone know what the black, red and yellow/blue wires go to? Naturally, the colors are duplicated in the harness and it is a pain trying to track them down. I figure that if I can find the sensors (or whatever) they go to, I can just wire them directly.
Thanks
Bill Wiseman