Keith Browning Posted March 29, 2013 Share Posted March 29, 2013 Sometimes you need to run a test under certain conditions that the test parameters won't allow. In this case the IDS EGR test which requires among other things that the engine oil temperature be above 186 degrees. Fine. I needed to run the test cold. Out comes my gauge tester and I disconnect the EOT sensor and dial in 200 degrees. Go to run the test and EOT shows at 46 degrees. Then I unplugged the ECT sensor and what do you know? Uh huh. In the test IDS shows EOT but it is really displaying ECT. Not that it matters in the grand scheme of things but I thought that was interesting. Simply unplugging the ECT made the temp default to 212 degrees on this particular vehicle. Quote Link to comment Share on other sites More sharing options...
mchan68 Posted March 29, 2013 Share Posted March 29, 2013 I have ran into situations before, where either the EOT wasn't plugged in properly during a recent repair or an issue with the EOT circuit itself. When this is the case, you will still see EOT readings (but I'm assuming they will be estimated values), but will also get a fan clutch cycling on more frequently during acceleration not to mention the MIL illuminating with a P0198 (I think that's the DTC number off the top of my head)setting as well. Quote Link to comment Share on other sites More sharing options...
Jim Warman Posted March 30, 2013 Share Posted March 30, 2013 foggy thinking aside, for some reason I thought and open ECT would generate a reading of -40. Of course the last time I recall trying anything with that was back in the days of EEC. Let's not forget that this also parks us back in the "computed value" conumdrum. It also appears that there is some chance that we may fall victim to some programmers alternative methods of dealing with out of range sensor values. Quote Link to comment Share on other sites More sharing options...
Keith Browning Posted March 30, 2013 Author Share Posted March 30, 2013 It just seemed funny that nothing changed until I pulled the ECT connector. Now I wish I took the 30 seconds to hook up the gauge tester to the ECT. Since both sensors were disconnected Jim may be correct in that the 212 degree reading was a default reading supplied by the PCM as you would expect an open in a temp sensor to full one way or the other. Quote Link to comment Share on other sites More sharing options...
Aaron Posted April 3, 2013 Share Posted April 3, 2013 foggy thinking aside, for some reason I thought and open ECT would generate a reading of -40. Of course the last time I recall trying anything with that was back in the days of EEC. Let's not forget that this also parks us back in the "computed value" conumdrum. It also appears that there is some chance that we may fall victim to some programmers alternative methods of dealing with out of range sensor values. I'm almost beginning to think that it's substituting high values to make other shit happen, be it fail safe, limp home, fan on "suck pedestrians through the grille" speed, etc. But you'd think that'd be built into the DTC for the open circuit on the sensor. I dunno. Beer. Quote Link to comment Share on other sites More sharing options...
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