My car has four trouble code PO121 P2176 PO221 PO123
2003 CADILLAC CTS
Car run only 5 mile on full truttle has check engine light on
have the same problem?
Sunday, May 18th, 2014 AT 11:25 PM
TPS has intermittent open or short internally, or the wiring harness is rubbing and causing an open or short, there could be a corroded or at the bad connection at the TPS, the PCM could be an issue.
This could be an issue with the ignition switch. The first thing you will want to do is check voltage at both sides of the "TAC" fuse in the under hood fuse block. It should be around 14 volts when the engine is at an idle. If there is no power at either side of the fuse, most likely you have an ignition switch problem. If the voltage at that fuse is ok, the electronic throttle body assembly is usually at problem.
This could be the result of an Throttle Position Sensor (TPS) harness is open or shorted, the Throttle Position Sensor (TPS) circuit has a poor electrical connection, a faulty Throttle Position Sensor (TPS), a fault with the Electric Throttle Control Actuator or throttle motor or an Accelerator Pedal Position Sensor (APP) issue
inspect all wiring and connectors that lead to the TPS. Also, check the voltage at the TPS. The voltage shouldn't spike over 4.65 volts KOEO. If it does, carefully trace each wire from the TPS harness to check for breaks in wiring or shorts.