scottwetzel Posted January 17, 2014 Share Posted January 17, 2014 I can't figure out why my red warning light is coming on my 88 superliner. My water temp is good and full my volts are good and oil pressure is good. Truck runs great. Any common sensors that go bad?? Quote Link to comment Share on other sites More sharing options...
r686st Posted January 17, 2014 Share Posted January 17, 2014 My "87 r686st does the same thing. Everything is fine and it comes on/off every so often. Quote Link to comment Share on other sites More sharing options...
cstaples Posted January 17, 2014 Share Posted January 17, 2014 (edited) Check your water level sensor on the top radiator tank. That's what makes mine go on '91 RD690P Edited January 17, 2014 by cstaples Quote Link to comment Share on other sites More sharing options...
Dirtymilkman Posted January 17, 2014 Share Posted January 17, 2014 Yep, water level sensor. Quote Link to comment Share on other sites More sharing options...
scottwetzel Posted January 17, 2014 Author Share Posted January 17, 2014 Is there a way to check it or should I just replace the water level sensor? Quote Link to comment Share on other sites More sharing options...
Brian Blaylock Posted January 17, 2014 Share Posted January 17, 2014 Make sure you have enough water in it first Quote Link to comment Share on other sites More sharing options...
gearhead204 Posted January 17, 2014 Share Posted January 17, 2014 take the wire off at center rear of top tank this should turn off lite. then remove sender if no coolant on sw. is good if coolant is present change sender Quote Link to comment Share on other sites More sharing options...
scottwetzel Posted January 19, 2014 Author Share Posted January 19, 2014 take the wire off at center rear of top tank this should turn off lite. then remove sender if no coolant on sw. is good if coolant is present change senderI took the wire off the center of the sensor and the light stayed on. I left the ground wire on tho. What now? Quote Link to comment Share on other sites More sharing options...
gearhead204 Posted January 20, 2014 Share Posted January 20, 2014 check the wire and make sure it didn't short to ground some where in the harness Quote Link to comment Share on other sites More sharing options...
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