Hello www_ropesmor,
This code P0123 is Throttle position sensor circuit high input.
There four basic reasons for this code.
1. An open or short to ground between the TPS (throttle position sensor) and the ECM (Engine control module).
2. A short to battery voltage between TPS and the ECM.
3. A short between the TPS wires.
4. A faulty TPS.
See below for connector diagrams.
First, with scan tool monitor TPS with throttle closed voltage should be
I f you don't have a scan tool, back probe terminal 1with a volt meter to ground and you will see the voltage as outlined above otherwise follow the steps below.
1.Check to see if there is about 5 volts at the TPS; with engine off key on disconnect the TPS back probe the harness side terminal 3 to ground with a volt meter if there is about 5 volts go to step 2 if about 5 volts if not repair the 5 volt circuit.
2. Probe the harness side terminal 2 to chassis ground with a volt meter, if voltage above .02 repair circuit 2 short to voltage. If voltage is .02 volts or below go to step 3.
3. Probe the harness side terminal 1 to ground with volt meter if below .5 volts go to step 4 if not repair short to battery between TSP harness and ECM connector
4 Turn the ignition off and disconnect the ECM connector . With an ohm meter measure the resistance between the ECM (terminal C18) and TPS ground circuit it should be below 1 ohm. Measure the resistance between the ECM (terminal C8) and TPS signal circuit it should be below 1 ohm. If not repair the open circuit.
After faulty circuit is found and repaired clear code and verify repair.
I hope this helps.
Regards,
netvan
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