CLUTCH TEST
Use the scan tool in order to perform the clutch test. Select the following information when
setting up the tool for running the test. Use the Shift Transmission feature on the scan tool to
complete the clutch test.
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
to Line Pressure Check. Apply the parking brake. Hold the service brakes with your left foot
and move the gear selector to DRIVE. Increase engine speed to 1,400 RPM with your right foot.
With soft keys, select UPSHIFT and shift the transmission from FIRST gear to SIXTH gear while
observing turbine speed. Turbine speed should increase momentarily and then drop to 0 RPM
when each gear is attained. Line pressure should drop momentarily, then gain pressure again when
each gear is attained.
Maintain 1,400 RPM and select the DOWNSHIFT soft key. Downshift the transmission from
SIXTH gear sequentially to FIRST gear while observing turbine speed. Turbine speed should
increase momentarily and then drop to 0 RPM when each gear is attained.
To further investigate a suspected leak in a clutch circuit, the clutch test should be repeated,
keeping the engine at idle speed. While performing the clutch test at 600 RPM, main pressure
should drop momentarily, then gain pressure again when each gear range is attained. If main
pressure remains low, suspect damaged seal in that range. If low pressure is in FIRST range only,
suspect Low and Reverse piston seal damage.
FASTLEARN PROCEDURE
OVERVIEW
2008 Chevrolet Silverado 1500
2008 TRANSMISSION Automatic Transmission - Allison - Cab & Chassis Sierra, Cab & Chassis Silverado, Sierra &
Silverado