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CLUTCH TEST Use the scan tool in order to perform the clutch test. Select the following information when 1. Select F0: Diagnostics and press ENTER. 2. Select Model Year. 3. Select LDTrk, MPV, Incomplete. 4. Select F0: Powertrain, press ENTER. 5. Select Engine size, press ENTER. 6. Select 6 Speed Automatic, press ENTER. 7. Select F2: Special Functions, press ENTER. 8. Select F1: Transmission Output Controls. 9. Select Shift Transmission. This allows the technician to shift the transmission and observe the integrity of each clutch/range in the transmission. Attach the transmission pressure gage as described in the Line Pressure Check Procedure. Refer Maintain 1,400 RPM and select the DOWNSHIFT soft key. Downshift the transmission from To further investigate a suspected leak in a clutch circuit, the clutch test should be repeated, FASTLEARN PROCEDURE OVERVIEW
2008 Chevrolet Silverado 1500 2008 TRANSMISSION Automatic Transmission - Allison - Cab & Chassis Sierra, Cab & Chassis Silverado, Sierra & Silverado
In general, FastLearn is a procedure for Allison 1000 Series transmissions in which a series of FastLearn must be used when one of the following repairs have been made to the vehicle: Transmission replacement or internal service/overhaul Valve body repair or replacement, including replacement of the pressure control solenoids TCM replacement TCM software/calibration update Any service in response to a shift quality concern The scan tool is used to initiate FastLearn by selecting the following commands: F3: Special Functions F1: Transmission Output Controls FastLearn Block the drive wheels. Apply the parking brake. Apply the service brake during DRIVE and REVERSE. 0 percent throttle and engine at idle RPM Transmission sump temperature is between 40-100°C (104-212°F) - Ref temp bargraph on If equipped, 4WD transfer case in 2WD Three steps are required to successfully complete the FastLearn procedure: IMPORTANT: When performing FastLearn, the following conditions must be met: IMPORTANT: If at any time during the procedure, required conditions are not met, FastLearn may abort and the process will need to be started
2008 Chevrolet Silverado 1500 2008 TRANSMISSION Automatic Transmission - Allison - Cab & Chassis Sierra, Cab & Chassis Silverado, Sierra & Silverado
1. PARK Mode 2. DRIVE Mode 3. REVERSE Mode PARK MODE While the transmission is in PARK, with the engine idling, FastLearn will cycle through a series DRIVE MODE Once all of the PARK test data have converged, the scan tool instructs the driver to select REVERSE MODE Next, the scan tool instructs the driver to select REVERSE. Once REVERSE is selected, the CAUTION: Block the wheels before selecting DRIVE. While in DRIVE, if the Scan Tool loses communication or becomes CAUTION: Block the wheels before selecting REVERSE. While in REVERSE, if the Scan Tool loses communication or becomes
2008 Chevrolet Silverado 1500 2008 TRANSMISSION Automatic Transmission - Allison - Cab & Chassis Sierra, Cab & Chassis Silverado, Sierra & Silverado
has converged. After learning the 1-2-3-4 and the low and reverse clutch volume, FastLearn updates the adaptive TROUBLESHOOTING If FastLearn will not run and the above stated conditions have been met, ensure the following: Transmission fluid temperature is between 40-100°C (104-212°F). Closed throttle and engine at warm idle RPM No active DTCs All speed sensors are connected and functioning properly. Internal mode switch is functioning properly Main pressure is within specification. TCC slip speed less than 100 RPM at idle in PARK/NEUTRAL LIMP HOME MODE PRINCIPLE OF OPERATION The Allison transmission incorporates control logic that enables the transmission to revert to a TEST PROCEDURE If a No Forward, No REVERSE, or Will Not Move condition occurs: 1. Set the parking brake. IMPORTANT: All shifts will be left in fast adaptive mode at this point.
2008 Chevrolet Silverado 1500 2008 TRANSMISSION Automatic Transmission - Allison - Cab & Chassis Sierra, Cab & Chassis Silverado, Sierra & Silverado
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