ElectronicsNeed help wiring something up? Thinking of adding an electrical component to your car? Need help troubleshooting that wiring glitch?
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My fan on my '88 SC always came on around 235, though I've heard numbers from 210 to 250. My solution was putting in a bypass switch. If you have a Haynes manual for your car, you can look in the wiring diagram to find the fan relay. It should show you the fan, the coolant temp. sensor, and the wiring between them, the ECM, and the AC circuit. All you have to do is splice in to the wire leading from the fan relay to the fan that becomes grounded when the relay is activated. Run that wire to a switch somewhere on the inside, and run the other side of the switch to a ground. I used a lighted switch to remind me that I have it on. When you flip the switch, the circuit is completed, and your fan comes on, keeping your engine nice and cool. I keep it on anytime I'm not on the highway. Also, doing it this way, you don't send the computer any message that would send into open loop mode. I also put in a lower thermostat, and my engine runs at a very happy 160. I still have the 2.8 V6 in, and it has to work pretty darn hard to pull that car. Before I did these changes, it was nothing to run up around 240-250. Good luck.
My engine goes into closed loop right at 160. When everything else gets warm enough, 160 is enough engine temp to kick it over. I checked it by running the in field service mode and watching when it kicked over. The only time I had problems not going into closed loop mode is on a cold day, but if I left the switch off, the engine would go up to around 180, which is what all the books say it should switch. Maybe something's just screwy with my computer, but I do know it's a stock chip. The lower thermostat doesn't mean it stays that cold all the time, but for my engine it was just a coincidence that it switched over there.