A few years ago, I bought (on Ebay) a new OEM Volvo engine harness for a 1982 B21F-MPG K-Jet engine. Not too long ago, I installed it because my original harness started crumbling away and was going to be a fire hazard. I had some assistance from a local foreign-car mechanic. He helped me identify the different harness connectors and where they went. Once I labeled them, I excused myself to use the bathroom. When I returned, he had pulled the old one out before I could document and photograph everything - like what wire colors were connected to what sensors and so forth. Shortly after I blew a gasket - metaphorically speaking, of course, I paid him his fifty bucks for his "help", and set about installing the new harness.

I layed out the harness roughly in the same general way as the original, and all the various connectors on the new harness would only reach to the places they were supposed to go - so far so good. I then find that I had one wire left - a single gray wire that fit onto a spade tip. I found only one place that the gray wire could both fit - and reach. It was the Lambda Sond Thermal Switch. I cleaned the spade-tip, applied dielectric grease, and snapped the two together. I thought everything was good to go, but as I secured the main connector at the firewall with zip ties, I noticed that the old original connector-half that came through the firewall on the driver's side had a green wire in the plug where the new harness connector had a gray wire.

When the two halves of the main harness connector were secured together, the gray wire and the green wire were connected together instead of a green wire to green wire. I do not know where the green wire on my old harness went to (mechanic tore it out before I could trace everything). I, therefore, do not know if the gray wire that is connected to the green wire, is connected to the correct sensor. I have looked at ALL of the relevant posts, and searched the archives, but the closest I can get is that the O2 Sensor wire is green, and one of the wires that goes to the oil pressure sensor and gauge is green. Beyond that, I do not know. Did I get snookered by someone who put a turbo harness into an OEM Volvo bag labeled for the 1982 MPG? My car, before installation had a low-power under load problem. After installation of the new harness, the low-power under load problem was still present. All dash gauges read correctly. The car starts and idles without problems, but the low-power under load persists. I have not yet unplugged the gray wire in the lambda-sond thermal switch to see if anything changes, but I think that's next. My basic question remains, however - what does the green wire in my main harness connector go to?