Diagnostic Aids

If the engine has been allowed to cool overnight to an ambient temperature, both coolant and MAT temperature may be checked with a "Scan" tester. The readings should be approximately the same. A Code 25 will result if circuit No. 472 is shorted to ground. If Code 25 is intermittent, see INTERMITTENTS in TESTS W/O CODES article.

Fig 1: Code 25, Circuit Wiring Diagram & Flow Chart

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