Chevrolet Silverado / GMC Sierra. Service manual — part 734

2. If necessary, clean each side of the filter plate assembly and install the filter plate assembly

back on the control solenoid (w/body and TCM) valve assembly. Clean the mounting
surface of the DT-47825 . See Special Tools.

3. Bolt the DT-47825 to the control solenoid (w/body and TCM) valve assembly mounting

surface. See Special Tools. Use the bolts and washers supplied with the tool to attach the
test block. Tighten the bolts to 5 N.m (44 lb in).

4. Connect the test harness supplied with the DT-47825 to the vehicle harness and to the TCM.

See Special Tools. Engage the connector locks.

5. Connect shop air to the DT-47825 air inlet. See Special Tools. Do not exceed the

recommended air pressure of 620.5-689.4 Kpa (90-100 psi).

6. With the ignition ON and the scan tool communicating with the vehicle, command the

solenoid in question On and Off. Watch the air pressure gage for a change as you command
the solenoid. Refer to Control Solenoid (w/Body and TCM) Valve Assembly Solenoid
Performance Test Plate to Component Identification for correct solenoid function and
test plate port connections for the solenoid being tested.

7. The solenoid should allow air pressure to flow or prevent air pressure flow depending on

the solenoid state. The test results are read on the pressure gage.

8. Command the solenoid valve On and Off several times to determine the condition of the

solenoid in question. Release the test air pressure from the pressure the gage between
solenoid tests.

Control Solenoid (w/Body and TCM) Valve Assembly Solenoid Performance Test Plate to
Component Identification

Solenoid

Test

Plate

Port

Key On, Engine

Off (KOEO)

Normal State

Commanded State

*Line PC Solenoid 1

G

No flow to gage

Increase/Decrease Approximately

68-103 Kpa (10-15 psi) per

command

PC Solenoid 2

C

No flow to gage

On - Full flow to

gage

Off - No flow to

gage

PC Solenoid 3

A

Full flow to gage

On - Full flow to

gage

Off - No flow to

gage

PC Solenoid 4

B

No flow to gage

On - Full flow to

gage

Off - No flow to

gage

PC Solenoid 5

F

No flow to gage

On - Full flow to

gage

Off - No flow to

gage

2008 Chevrolet Silverado 1500

2008 TRANSMISSION Automatic Transmission - 6L50/6L80/6L90 - Cab & Chassis Sierra, Cab & Chassis Silverado,

Sierra & Silverado

SERVICE FAST LEARN ADAPTS

Service Fast Learn Adapts is a procedure for 6 speed automatic transmissions in which a series of
tests are run to allow the transmission control module (TCM) to learn individual clutch
characteristics. Once the clutch data is learned, Service Fast Learn Adapts translates it into the
adaptive data cells, which the TCM uses for clutch control during shifts. The scan tool provides
initiation of the Service Fast Learn Adapts procedure. This procedure is to be used following
transmission repair.

The Service Fast Learn Adapts procedure must be performed when one of the following repairs
have been made to the vehicle. Failure to perform the procedure after one of the following
repairs may result in poor transmission performance, as well as transmission DTCs being set:

Transmission internal service/overhaul

Valve body repair or replacement

Control solenoid (w/body and TCM) valve assembly replacement

TCM software/calibration update

Any service in response to a shift quality concern

Shift Solenoid 1

H

Full flow to gage

Off - No flow to

gage

On - Full flow to

gage

Shift Solenoid 2

D

No flow to gage

Off - No flow to

gage

On - Full flow to

gage

TCC PC Solenoid

E

No flow to gage

On - Full flow to

gage

Off - No flow to

gage

* Increment solenoid to maximum pressure and then decrease to minimum pressure to ensure
full range of operation.

IMPORTANT: Ensure the following conditions are met before performing the

Service Fast Learn Adapts procedure:

Drive wheels are blocked

Parking brake is applied

Service brake is applied

Zero percent throttle and no external engine RPM control

Transmission fluid temperature (TFT) is between 70-100°C
(158-212°F)

2008 Chevrolet Silverado 1500

2008 TRANSMISSION Automatic Transmission - 6L50/6L80/6L90 - Cab & Chassis Sierra, Cab & Chassis Silverado,

Sierra & Silverado

1. Using the scan tool, navigate to Service Fast Learn Adapts commands.

1. F1: Transmission Control Module

2. F5: Module Setup

3. F0: Fast Learn Adapts Process

2. Use the scan tool to perform the Service Fast Learn Adapts procedure.

1. PARK test setup

2. DRIVE mode

3. REVERSE mode

These stages are automatically initiated and controlled by the scan tool. As the
procedure is being performed, the scan tool data display will provide operator
instructions. Follow the scan tool instructions as required. For a brief description of
each stage, refer to PARK Test Setup, DRIVE Mode, and REVERSE Mode
below.

3. Once the procedure is complete, shut OFF the engine and power down the TCM. You will

lose communication to the scan tool.

4. Restart the engine. This will complete the Service Fast Learn Adapts procedure.

The following are brief descriptions of each of the 3 different stages.

PARK TEST SETUP

While the transmission is in PARK, Service Fast Learn Adapts will prepare for test cycles. The
test preparation will include the diagnostic criteria checks, safety checks, vehicle status checks,
and then will perform internal transmission test preparation functions such as clutch air purging.

Transmission gear selector has been cycled from Park to
Reverse 3 times in order to purge air from the reverse
clutches.

IMPORTANT: If at any time during the procedure, required conditions are

not met, Service Fast Learn Adapts may abort and the
process may need to be started again from the beginning.

IMPORTANT: There are 3 stages required to successfully complete the

Service Fast Learn Adapts procedure:

2008 Chevrolet Silverado 1500

2008 TRANSMISSION Automatic Transmission - 6L50/6L80/6L90 - Cab & Chassis Sierra, Cab & Chassis Silverado,

Sierra & Silverado

The scan tool will instruct the operator to select park and apply the brake only.

DRIVE MODE

Once the PARK setup has completed, the scan tool instructs the driver to select DRIVE. Once
DRIVE is selected, the TCM engages the individual clutches to learn the clutch volume, full feed
fill thresholds, and pressure offsets. The TCM will only cycle through this test once. Running the
Service Fast Learn Adapts procedure multiple times will give the same results and is not
necessary.

REVERSE MODE

Next, the scan tool instructs the driver to select REVERSE. The TCM engages the individual
clutches to learn the clutch volume, full feed fill thresholds, and pressure offsets. The TCM will
only cycle through this test one time. Running the Service Fast Learn Adapts procedure multiple
times will give the same results.

TROUBLESHOOTING

If the Service Fast Learn Adapts will not run and the above stated conditions have been met,
ensure the following:

TFT is between 70-100°C (158-212°F).

Brakes and brake switch are functioning properly.

No active DTCs.

CAUTION: Block the wheels before selecting DRIVE. While in DRIVE, if

the Scan Tool loses communication or becomes
disconnected, the vehicle could move forward. Failure to
block the wheels could result in personal injury or property
damage.

CAUTION: Block the wheels before selecting REVERSE. While in

REVERSE, if the Scan Tool loses communication or becomes
disconnected, the vehicle could move backward. Failure to
block the wheels could result in personal injury or property
damage.

IMPORTANT: When the Service Fast Learn Adapts procedure is completed, the

transmission will remain in a neutral state.

2008 Chevrolet Silverado 1500

2008 TRANSMISSION Automatic Transmission - 6L50/6L80/6L90 - Cab & Chassis Sierra, Cab & Chassis Silverado,

Sierra & Silverado