Question about 1990 Chevrolet Lumina
Code 12 flashes any time trouble codes are pulled without the car running. It is normal and think it has something to do with not receiving distributor pulse.
Code 21 has to do with the TPS (throttle position sensor) voltage being to high. You'll need a DVOM (digital volt ohm meter) to check this out. Unplug the TPS sensor and check for 5volts on the grey wire, and make sure the black wire has a good ground. If those check out plug the sensor back in. Back probe the blue wire. you should see around .5 volts with the throttle closed. The voltage should go up smoothly as you slowly open the throttle. At wide open throttle the voltage should be around 4.9 volts. If any of the above three are not true I would suspect a bad throttle position sensor.
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Posted on Oct 24, 2010
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Posted on Jan 02, 2017
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