P1877
DTC P1877 (3.5L)
Circuit Description
The transmission adaptive pressure (TAP) Shift system allows the driver to manually shift gears by using the TAP Shift switches located on the Automatic Transmission Shifter. Pushing the Up switch will command an upshift and pushing the Down switch will command a downshift. The TAP Shift system is activated when the gear selector is in the D3 position and is deactivated in all other positions.
If the powertrain control module (PCM) detects TAP enable switch Inactive and the TR switch indicates D3, DTC P1877 sets. DTC P1877 is a type C DTC.
DTC Descriptor
This diagnostic procedure supports the following DTC:
DTC P1877 Up and Down Shift Switch Performance - Range Switch in D3
Conditions for Running the DTC
^ No TAP system DTCs P0815, P0816 or P0826.
^ No PSA DTCs P1810, P1816, or P1818.
^ No TAP system performance DTC 1876.
^ The engine run time is greater than 5 seconds and not in fuel cut off.
Conditions for Setting the DTC
The PCM detects the TAP enable switch is Inactive and the TR switch is D3 for 60 seconds.
Action Taken When the DTC Sets
^ The PCM does not illuminate the malfunction indicator lamp (MIL).
^ The PCM disables TAP Shift operation.
^ The PCM commands an alternate coast shift pattern where downshifts occur at higher vehicle speeds while coasting.
^ The PCM records the operating conditions when the Conditions for Setting the DTC are met. The PCM stores this information a Failure Record.
^ The PCM stores DTC P1877 in PCM history.
Conditions for Clearing the DTC
^ A scan tool can clear the DTC.
^ The PCM clears the DTC from PCM history if the vehicle completes 40 warm-up cycles without a non emission related diagnostic fault occurring.
