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Home >> Geo >> 1990 >> Storm Base, Standard >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - Tests W/Codes >> Code 21A, Throttle Position Sensor Circuit >> Diagnostic Aids

Diagnostic Aids

With throttle closed, TPS voltage should be less than 1.25 volt. TPS voltage should steadily increase as throttle is opened. Code 21A will appear if Purple/Red wire is shorted to voltage. If code is intermittent, see TESTS W/O CODES article.

Fig 1: Code 21A Circuit Diagram
G90B15827
Fig 2: Code 21A Flow Chart
G90C15828