91GPLQ1 Posted October 23, 2014 Report Share Posted October 23, 2014 Hi, got the "service engine soon" light intermittent, checked code #15 and replaced the coolant sensor. Still got the "service engine soon", now permanent and code #15 after working on it all day! What could possibly be wrong? Car is my 1991 GP LQ1. Thank you! Quote Link to comment Share on other sites More sharing options...
Imp558 Posted October 23, 2014 Report Share Posted October 23, 2014 Get a pinout for the PCM and test continuity from the plug to the ECM connector. (Always disconnect the battery before removing or installing any ECM/PCM) It could be an open connection, since it got worse after you were in there I'd suspect it's broken at the crimp in the ECTS plug. Quote Link to comment Share on other sites More sharing options...
91GPLQ1 Posted October 23, 2014 Author Report Share Posted October 23, 2014 (edited) Been out in the garage since i posted. Checked the yellow an black cables in the connectors behind the coolant tank, nothing. Then out with the airfilter box and off with the coolant sensor connector checking the cables good. Checking sensor resistance good. WTF! Then i pinched the terminals in the sensor connection and plugged it onto the sensor and checking resistance in yellow and black cables at connectors behind the coolant tank. And now i have the same resistance as at the sensor. Test drive and everything is fine, no "service engine soon" light and no code 15! And since i had everything off the first time now i got new LIMG and UIMG and a new connection in the LIM for the heater hose too. A good day after all! And thank you imp558, you were right on the open circuit! Edited October 23, 2014 by 91GPLQ1 Quote Link to comment Share on other sites More sharing options...
Imp558 Posted October 24, 2014 Report Share Posted October 24, 2014 You're welcome.Doesn't sound like it's "fixed" though, you really should expose the problem and bust out the soldering iron. Quote Link to comment Share on other sites More sharing options...
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