I am getting ECM Trouble Code 22 on my 1988 Chevy pickup with a 350 throttle body engine. Code 22 is low voltage on the throttle position sensor. If I replace the TPS will that solve my problem? Right now, the truck will idle at very high rpm and stall when put into gear.
The sensor itself may or may not be the fix. It would make things really simple if a quick part swap cured every computer-related problem. It's usually not that easy, but the Throttle Position Sensor circuits on your Chevy truck are very basic. They consist of a 5-volt reference, a ground and a signal circuit all wired from the TPS directly to the ECM (Electronic Control Module).
You could just cross your fingers and buy a Throttle Position Sensor, or you could have a qualified technician hook up a Scan Tool and diagnose the problem accurately in a couple of minutes.
When observing normal TPS voltage on a Scan Tool, the readings will vary from about .5-volts at idle to about 5-volts at WOT (wide-open throttle). If the low voltage problem which set the code 22 is a hard failure and still present, you will see a reading below .2-volts on the scanner. If disconnecting the sensor brings the voltage up to 5-volts, this officially condemns the Throttle Position Sensor.
If that's not the case, it will require further testing for shorts, poor connections or open circuits. When all else is eliminated that leaves you with a faulty ECM.