Engine code showed 22. checked wiring to tps was all good. idle does surge 200 to 300 rpm . 1000 to 1500 rpm is where it wants too start up.
Make sure the idle screw was not turnned causeing tps sensor to read over the spec limit, the next then is to make sure the idle air control valve is working , a bad valve will cause this problem and last is the stepper motor that controls the idle. some of these around this year used steeper idle control motors instead of idle air control valves and in turn the stepper motor is bad it will hold the throtle plate open to much causing the tps reading to be wrong triggering the engine light to come on. the steeper motor will be boltted to side of the throtlebody and theres a small arm to the throtle linkage. i will enclose a stepper motor picture and an idle air valve to show you, but this sounds like the tps is out of range due to this. the last thing is to make sure there are no vacuum leaks, spray crab cleaner around throtlebody base gasket and also the intake mounting gasket and see if the idle changes is so theres a vac leak in that area. good day. okay just did a little research and this truck does have a idle air control valve, the picture is encolsed and is screwed into throtlebody, check that and for vacuum leaks, make sure tps is good sometime it will test good when testing and go bad when it wants, you could have a bad tps and idle air control valve also.
A P0123 code means that the computer has detected that the TPS (throttle position sensor) is reporting too high a voltage.
Symptoms may include:
A code P0123 may mean that one or more of the following has happened:
If there are no symptoms, the simplest thing to do is to reset the code and see if it comes back.
If there are symptoms such as the engine is stumbling or hesitating, carefully inspect all wiring and connectors that lead to the TPS. More than likely the problem is with the TPS wiring. Check the voltage at the TPS (refer to a service manual for your vehicle for this specific information). If the voltage spikes or is too high (over 4.65 volts with key on, engine off), then that is indicative of a problem. Carefully trace each wire from the TPS wiring harness to check for breaks, rubbing against other components, etc.
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