[Gmecm] GM Trans Pressure Adaptive memory question

Sat Jan 14 16:03:01 UTC 2006

The symptoms you describe are exactly inline with
problems a LOT of 4T65's have. There is a bulletin out
that addresses this concern and I will attach it to
this post. This condition did NOT always set trouble
codes and does NOT require the removal of the trans to
repair. The cause of the problem was a sticky pressure
control soleniod and it does whatever it wants once it
starts to stick. The replacement of these solenoids
can be labor intensive as they are located in the side
cover of the trans and not the bottom. I'm not sure if
it is necessary to drop down the cradle in the cars to
remove the side cover but it was necessary on the
vans. My first step if I were you would be to check
for trouble codes and if it does have some stored that
match the ones in this bulletin then you have your
answer. If it doesnt have any trouble codes stored
then I would look at some trans pressure readings.
Please be aware that in a LOT of cases you may not
find anything out of the norm as it is an intermittent
problem most of the time and it will appear normal
while it is not acting up. In any case the solenoid
itself is relatively inexpensive and is still
definately easier to replace than the entire trans so
if you find most of your diagnostics inconclusive I
would still try it versus trans replacement. In about
80-90% of the cases with symptoms I have seen they
were resolved with a new solenoid. Another suggestion
would be to service the trans fluid and filter after
replacing the solenoid as it is debris that causes
them to stick in the first place. Hope this
helps..........

Slips, Harsh Upshift or Garage Shifts, Launch
Shudders, Flares, Erratic Shifts and Intermittent
Concerns, DTC P1811 or P0748 Set (Replace Pressure
Control Solenoid Valve Assembly) #00-07-30-002B - (Jul
19, 2002)

Table 1: Line Pressure Specification Table 
Slips, Harsh Upshift or Garage Shifts, Launch
Shudders, Flares, Erratic Shifts and Intermittent
Concerns, DTC P1811 or P0748 Set (Replace Pressure
Control Solenoid Valve Assembly)
1997-1999 Buick Riviera

1997-2002 Buick Park Avenue

1998-2002 Buick LeSabre

1999-2002 Buick Regal

2000-2002 Buick Century

2002 Buick Rendezvous

1997-2001 Chevrolet Lumina

1997-2002 Chevrolet Monte Carlo

1999-2002 Chevrolet Venture

2000-2002 Chevrolet Impala

1997- 1999 Oldsmobile Eighty Eight

1997-2002 Oldsmobile Silhouette

1998-2002 Oldsmobile Intrigue

2001-2002 Oldsmobile Aurora (3.5L)

1997-2002 Pontiac Bonneville, Grand Prix

1999-2002 Pontiac Transport/Montana

2001-2002 Pontiac Aztek

with Hydra-Matic 4T65-E (RPOs MN3, MN7, M15, M76)

This bulletin is being revised to add additional
models and model years. Please discard Corporate
Bulletin Number 00-07-30-002A (Section --Automatic
Transmission).

Condition
Some owners of the above vehicles with a Hydra-Matic
4T65-E transaxle may comment on harsh upshifts or
harsh garage shifts, soft shifts, shudders on hard
acceleration, or shifts erratic. These conditions may
appear intermittently or set a DTC P1811 or P0748.
During diagnosis, a low or high line pressure (actual
versus desired) may be observed.

Cause
The above condition may be due to any one of the
following which may affect line pressure output:

   ?  Sediment inside the pressure control (PC)
solenoid valve, causing the PC solenoid valve to
mechanically bind.  

   ?  Sediment in the valve body, causing the torque
signal regulator valve to stick.  

   ?  Incorrect transaxle oil level.  

Correction
Important: Any of the above conditions may be
intermittent, therefore, this test should be performed
at least three times.

Refer to the Line Pressure Check Procedure in SI,
along with the Line Pressure Specification Table
below, to determine if actual versus desired pressures
are within the values specified. The Scan Tool is only
able to control the PC solenoid valve in PARK and
NEUTRAL with the vehicle stopped. This protects the
clutches from extremely high or low pressures in DRIVE
or REVERSE ranges.

Refer to the Line Pressure Specification Table below.
The pressures in the table assume a temperature of
70?C. The pressure will vary with a change in
temperature.

Line Pressure Specification Table Pressure Control
Solenoid Valve Current
 Approximate Line Pressure*

Metric
 English

0 amp
 1675-2137 kPa
 243-310 psi

0.1 amp
 1662-2124 kPa
 241-308 psi

0.2 amp
 1613-2103 kPa
 234-305 psi

0.3 amp
 1551-2068 kPa
 225-300 psi

0.4 amp
 1448-1986 kPa
 210-288 psi

0.5 amp
 1310-1903 kPa
 190-276 psi

0.6 amp
 1172-1751 kPa
 170-254 psi

0.7 amp
 1000-1531 kPa
 145-222 psi

0.8 amp
 793-1227 kPa
 115-178 psi

0.9 amp
 565-896 kPa
 82-130 psi

1 amp
 469-641 kPa
 68-93 psi

1.1 amp
 448-552 kPa
 65-80 psi

*Approximate Line Pressure is measured at an engine
speed of 1400 RPM.

If the actual versus desired pressures are not within
the values specified, clean the valve body and replace
the PC solenoid valve, if necessary.

Check the PC solenoid valve actual versus desired
pressures to verify the new PC solenoid valve is
responding correctly.

Refer to the Automatic Transaxle Section of the
Service Manual for the proper repair procedure.

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