Chevrolet Silverado 2500 HD transmission limp mode after module and pigtail replacement on Chevrolet Silverado 2500 HD

Some Chevrolet Silverado 2500 HD owners report experiencing transmission limp mode after replacing the module and pigtail, which can be attributed to several factors. Issues with the throttle position sensor (TPS) circuit may prevent the PCM from determining the correct transmission shifts, potentially triggering a check engine light with codes like P0122. Additionally, a faulty transmission fuse could result in being stuck in limp mode, necessitating thorough testing. Owners may also encounter diagnostic codes such as P0700, indicating discrepancies between the Input RPM Sensor and Transmission Output RPM, which can complicate transmission diagnostics. Furthermore, improper PCM programming following component replacements may lead to the vehicle defaulting to limp mode, and incorrectly swapped sensor connectors could cause speed sensing issues. It is recommended that owners check these components and connections carefully, and seek professional assistance if problems persist.