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Home >> Isuzu >> 1990 >> Trooper LS, 2.8 R, Standard >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - Tests W/Codes - 2.8L >> Diagnostic Circuit Check >> Code 21: TPS Circuit (Signal Volt High) >> Notes

Code 21: TPS Circuit (Signal Volt High): Notes

NOTE: Test numbers refer to test numbers on diagnostic chart.
  1. Code 21 will set if TPS signal voltage is greater than 2.5 volts, vacuum is greater than 15 in. Hg and all conditions are met for 8 seconds.
  2. With TPS sensor disconnected, if the ECM and wiring are okay, TPS voltage should drop.
  3. Using a test light connected to 12 volts, probe sensor ground circuit No. 452. This checks 5-volt return circuit. If there is a faulty 5-volt return, Code 21 will set.
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