DTC P0877: Transmission Fluid Pressure (TFP) Switch 4 Circuit Low Voltage
The transmission fluid pressure (TFP) switch 4 is part of the control solenoid (w/body and TCM) valve assembly and is not serviced separately. The TCM supplies 12 volts to the TFP switch 4 on the TFP switch 4 signal circuit; the TFP switch 4 has an internal case ground. TFP switch 4 is normally closed, Low. When oil pressure is present at the TFP switch 4, the switch is open, high. The normally low clutch pressure control (PC) solenoid 4-5 controls the transmission fluid to the 1-2-3-4 clutch. The TCM monitors the normally closed TFP switch 4 signal circuit to determine the 1-2-3-4 clutch status.
P0877
The TCM detects that the TFP switch 4 signal voltage remains low, 0 volts when the 1-2-3-4 clutch is commanded ON for 5.5 seconds or greater.
Action Taken When the DTC Sets
• DTCs P0877 and P0878 are Type C DTCs.
• The TCM freezes transmission adaptive functions.
Circuit/System Testing
Ensure the TFT is near the temperature displayed in the Failure Records.
Start the engine and place the transmission range selector in D6.
Observe the TFP switch 4 parameter while commanding 4th gear and then commanding 5th gear with the scan tool. The TFP Switch 4 should transition from High in 4th gear to Low in 5th gear.
? If the TFP switch 4 parameter state does not change, perform the Control Solenoid Valve and Transmission Control Module Assembly Inspection .
? If no concerns are found, replace the control solenoid (w/body and TCM) valve assembly.
Component Testing
Perform the Control Solenoid Valve and Transmission Control Module Assembly Inspection .
Repair Instructions
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
Control solenoid (w/body and TCM) valve assembly replacement - refer to Control Module References for replacement, setup, and programming.
Perform the Service Fast Learn Adapts
SOURCE: GMC automatic transmission
I'm told and read a sun shell may be broke. Common problem for this vehicle. Shop will possibly rebuild and use aftermarket kit parts to correct problems the transmission had originally. Cost is probably between $1300 to 1600 to repair. Good luck I got the same problem on a 97 Jimmy and 3 shops said the same thing.
SOURCE: check automatic transmission fluid level
Dipstick is to the left of the engine. Should be a small yellow dipstick. Add fluid through the dipstick hole. The vehicle should be running when you do this. It is best to have driven at least 20 miles before adding trans fluid so everything has had time to get hot.
SOURCE: cant locate where to put my tranmissin fluid
usually you fill them through the transmission tube that has the dipstick in it, just put a funnel in the top of the tube and add the fluid but check to make sure you do not overfill it
Hope this helps
SOURCE: is there a transmission fluid dipstick on 2007 cobalts
big red
the leak migh be coming from the tranny pan check it out just remove the pan replace the seal and filter and fill it back up it will just take you a trip to the autopart store and 20 minutes to get it fix
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