While researching my swap to TBI, I ran across a couple of people who suggested applying a switched power to the A/C sensing circuit to cause the engine to idle higher when the switch is on. While there were references to doing this, I could not find anyone who actually did it. It sounds great for winch operation, or extra warm-up time on cold mornings. Well, I did, and here is what I found: First, this probably means you are not using the A/C circuit for A/C. I do not have the A/C hooked up, and did away with the compressor by installing an A/C delete pulley on my newly installed serpentine belt system. To start this project, find the dark green wire going to pin B8 on the ECM. This wire provides 12v sensing signal to the ECM, making the computer go to the higher idle rpm to compensate for a higher engine load from the A/C compressor. I made a small switch panel in the space previously occupied by a dash vent above my stereo. I added a lighted switch that has a red LED to show me when the circuit is on. I wired it to an "ignition hot" circuit that was available on my new painless fuse block that I used when converting to TBI. Easy install, just a switched 12v circuit. Results: Oddly, I expected the switch to cause the engine to idle up a couple hundred extra rpm whenever switched on. This proved NOT to be the case. When cold, the engine would increase rpm by around 200 rpm. Once warm, most of the time the increase was only 50-100 rpm . Sometimes it would go higher, somtimes not. This should work well for additional power from the alternator during winch use. This is the primary reason I decided to try it. 50-200 rpm will increase the alternators output in those times of winch use (but I'm hoping to get stuck less with the new detroit installed ). I think the ECM adjusts rpm depending on temperature. If that is true, in order to get a full 200 rpm when switching the circuit on, a double-pole, double-throw switch could be used to disconnect the temperature sensor and cause the ECM to run in open-loop when you want the high-idle mode. I have yet to test this theory. Minor project, but looks to be a useful design and purpose. Please feel free to add anything I missed.