| Subject: | Referencing DTC P0748 Diagnostic Procedure For Harsh Shift
and/or Harsh Garage Shift Concerns |
| Models: | 2001 Cadillac DeVille, Eldorado, Seville |
| with 4T80-E Automatic Transmission (RPO MH1) |
In some instances, when diagnosing concerns on harsh shifts while driving
and/or harsh garage shifts, a Diagnostic Trouble Code (DTC) P0748
may be set. When a DTC P0748 is set, one of the actions taken is to
default line pressure to a high value. As a result, shifts will have a harsher
feel. Causes for the DTC P0748 may be in the pressure control (PC)
solenoid valve, internal or external wire harnesses, or the powertrain control
module (PCM). If DTC P0748 is set, published diagnostics will successfully
lead the technician to replace the correct component. It is important to follow
the step procedures for DTC P0748 to correctly identify the root cause
of the high line pressure and avoid replacing good components.
