P0877 AllisonP0877 - Pressure Switch Reverse Circuit Low Description - This test detects Reverse Pressure Switch closed indication by comparing the Reverse Pressure Switch state to the PRNDL switch state. The auto repair's diagnosis time and labor rates vary by location, vehicle's make and model, and even your engine type. What does OBD-II fault code P0877 mean? OBD-II Code Transmission may not shift properly is defined as a Transmission Fluid Pressure Sensor/Switch "D" Circuit Low. Original codes were P0756 & P0975. The transmission fluid temperature is 0°C (32°F) or greater. As stated in last post, the codes are not consistent, sometimes it relates to trans pressure sensors, other times it is solenoids. P0877 code definition. P0877 is typically an electrical circuit (TFPS sensor circuit) issue. So, for codes P0848 and P0877, assume that you are sucking air, and try to find out why. All of them were correctly installed. Got a 2002 LB7 with the Allison 1000. Since this is an electrical failure, the PCM/TCM can compensate to some degree. A P0872 diagnostic trouble code is actually pretty serious, as it could be caused by either a failed sensor or hydraulic pressure issues. A P0877 code is registered when the powertrain control module (PCM) is registering transmission fluid pressure that is above or below factory spec. The PCM or TCM uses the voltage signal from the TFPS to determine the transmission pressure and informs other controllers that utilize the vehicle. In either case, drivability issues can occur. 6T75E Transmission - Failed Pressure Switches on TCMP0842 Transmission Fluid Pressure (TFP) Switch, Circuit Voltage Low. Pressure switch 1 (PS1) monitors shift valve 1 positioning and relays it to the TCM. Though the effects may not be noticeable initially, it can lead to a more complicated problem in the long run. Discussion Starter · Jun 1, 2021. to replace valve body, internal mode switch and pressure manifold switch. The Transmission Fluid Pressure Sensor tells the Transmission control module (TCM) the pressure of the fluid going through the transmission. P0708: Transmission Range Sensor Circuit High Input DTC Trouble Code The presence of a P0708 diagnostic trouble code means that the transmission range sensor / neutral safety switch is sending the wrong signals back to the ECM. Symptoms of a P0877 engine code may include: Fault indicator light is on Change the quality of the shift The car starts to move in 2nd or 3rd gear (limping in mode).