Experiencing issues with your 47re transmission, particularly if it’s stuck in first gear? This can be a frustrating problem, impacting your vehicle’s performance and driveability. Modern vehicles are equipped with onboard diagnostic systems, and using an OBD2 scanner can provide valuable insights into transmission problems. Let’s explore a scenario where a driver encountered this issue and how OBD2 diagnostics played a role.
One driver reported their truck experiencing smooth shifting initially, but after a brief stop, the transmission became stuck in first gear. Regardless of engine RPM, the transmission refused to shift to higher gears. Interestingly, by releasing the throttle, the transmission would shift, and subsequently, all other gears and torque converter lockup functioned normally. However, at typical shifting RPMs, the truck seemed to lose power and exhibit signs of slipping.
Seeking professional help, the driver took their truck to a mechanic who utilized an OBD2 scanner to assess the vehicle’s parameters. While no major diagnostic trouble codes (DTCs) were present, the OBD2 scan revealed an anomaly with the throttle position sensor (TPS). At idle, the TPS readings fluctuated erratically between 37% and 48%. Furthermore, the scanner indicated that the truck’s computer mistakenly registered the transmission as being in second gear even before an actual shift occurred while driving.
Based on these OBD2 readings, a mechanic suggested that electrical interference, possibly from a grounding issue with the alternator wiring, could be the root cause. The theory was that static or electrical noise was disrupting the TPS signal, leading to incorrect transmission behavior. Rerouting the alternator ground wire was attempted to mitigate potential interference, but unfortunately, this did not resolve the problem. Despite confirming that the transmission fluid level was adequate and the fluid itself was not burnt, the issue persisted, leaving the driver seeking further diagnostic avenues for their 47re transmission problem.
This case highlights the importance of OBD2 scanners in diagnosing transmission issues, even when traditional DTCs are absent. Erratic sensor readings, like the fluctuating TPS in this example, can offer crucial clues. While a simple grounding fix didn’t solve this particular problem, the OBD2 scan provided valuable data points for further investigation into potential electrical or sensor-related faults within the 47re transmission system. Further diagnostics might include a more in-depth examination of the TPS itself, the wiring harness, and potentially internal transmission components.
