Diagnostic Aids
The "Scan" tester displays throttle position in volts. Closed throttle voltage should be less than 1.25 volts. TPS voltage should increase at a steady rate as throttle is moved to WOT. A Code 21 will result if circuit No. 452 is open or if circuit No. 417 is shorted to voltage. If Code 21 is intermittent, see INTERMITTENTS in TESTS W/O CODES article.