Robert U Posted March 1, 2022 Share Posted March 1, 2022 I have an intermittent warning light when the coolant temp goes to 191 degrees or above. ISC8.3 engine normal temp 189 degrees. New radiator ,cac , water pump, thermostat, hoses installed 2 years ago. Have had problem before and after. Wiring diagram shows coolant temp sensor only wired to temp gauge and not to ecm. It shows warning light coming from ecm. How does the ecm gets coolant temp info ? Bob U 2000Dip Link to comment Share on other sites More sharing options...
jacwjames Posted March 1, 2022 Share Posted March 1, 2022 Here is a list of sensors for my 8.3L ISC. Not sure where this sensor is located. Interesting to note that Monaco installed their own sensors for the dash gauges. My Silverleaf VMSpc monitors and reports the ECM information, which seems to be more accurate then the dash gauges. Cummins ECM sensors.pdf Link to comment Share on other sites More sharing options...
Rocketman3 Posted March 1, 2022 Share Posted March 1, 2022 (edited) In watching my rigs temp (2000 Dynasty), I have the silver leaf setup watching the ecm. It “appears” to me the dash warning light and buzzer are taken from the cooling tank overflow (or somewhere else in the coolant lines) and not from the ECM. There seems to be a difference between the temperatures the ECM reports and the warning buzzer and light. The warning buzzer and light slowly ramps up from no sound - then a little - more sound and the light starts to flash intermittently - to finally full light and full buzzer - then goes back down the same way. Don’t know if that helps - or even if I am completely correct. Edited March 1, 2022 by Rocketman3 Link to comment Share on other sites More sharing options...
Jim Byrd Posted March 1, 2022 Share Posted March 1, 2022 I recommend you purchase the ScanGageD and you can view all of the ECM values plus fault codes. Cost around $150 at Camping World when on sale. Link to comment Share on other sites More sharing options...
Gary 05 AMB DST Posted March 2, 2022 Share Posted March 2, 2022 What is the warning light showing? Could it be the coolant level sensor? Gary 05 AMB DST Link to comment Share on other sites More sharing options...
Robert U Posted October 18, 2022 Author Share Posted October 18, 2022 Warning light fix for my 2000 Diplomat. Thanks to JACWJAMES I found the coolant temperature gauge sensor that feeds the ECM. It is located just below the thermostat. I replaced it in June and have not had a warning light in over 1000 miles. The coolant temperature gauge on the dash was accurate. Bob U 2000 Dip Link to comment Share on other sites More sharing options...
Gary 05 AMB DST Posted October 19, 2022 Share Posted October 19, 2022 Bob, Glad you solved the problem. On my 05 Ambassador, the coolant sensor is on the coolant tank, not the engine. Gary 05 AMB DST Link to comment Share on other sites More sharing options...
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