ECTS showing 20*F below ambient at startup

[froggy81500]

the pre-obd-ii saturns had two, one the ECTS and the other was the sending unit for the gauge. To the best of my knowledge the obd-ii (96 and up) there is only one ECTS that the gauge gets its signal from also. I don't have my haynes manual close by so I can't readily look it up but I do remember this conversation at saturnfans. The ects issue has got to be the most common issue for those motors. make sure the replacement one has a brass tip. the original ones and the junk ones had a plastic tip and is the reason why they were always going bad. Now, the resistance reading of the ects goes down as its temperature goes up. In order for it to read colder than it should, there is resistance added to that circuit. It could be a bad sensor. It also could be a wiring issue. Check the electrical connections both in the sensor and at the end of the connector for corrosion or what not. Check your splices (if you spliced a new connector on). Also check the wiring for any spots that look kinked or otherwise compromised. You can also check those wires with the sensor unplugged, as well as check the resistance of the sensor with it unplugged. Using an ohmeter check the resistance of the ects and compare it to the chart of what the resistance should be at whatever ambient temperature is. To check the wiring, you can check the ground wire by using an ohmeter. I am not sure if it is a straight ground or if it is grounded thru the pcm. Take one probe of the ohmeter to the ground wire in the connector (unplugged of course) and the other probe to ground. You should have very little to no resistance. If you do get some resistance, check it again with the key on just in case the pcm does do the grounding for it. Next, check the +5 volt wire, should be yellow if I am not mistaken. This you need the key on for. This time with a voltmeter. One probe on the + wire, the other to ground. You should see 5 volts, or very close to it. Anyting less than maybe 4.7 volts and you should check that wire for a bad spot.