Diagnostic Aids
The "Scan" tester reads engine temperature in degrees centigrade. After engine is started, temperature should rise steadily to about 194°F (90°C), then stabilize when thermostat opens. When a Code 14 is set, the ECM will turn on engine cooling fan. A Code 14 will result if circuit No. 410 is shorted to ground. If Code 14 is intermittent, see INTERMITTENTS in TESTS W/O CODES article.