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If this is what your feeling then there is a SSM which applies.
NNN-NN-NNNN2005 F-150/E-SERIES/EXPEDITION WITH 4R70W/E OR 4R75W/E - INTERMITTENT CLUNK ON 3-2 DOWNSHIFT DURING COASTDOWN/TIP-IN
2000-2005 F-150, E-SERIES OR EXPEDITION VEHICLES EQUIPPED WITH A 4R70W/E OR 4R75W/E TRANSMISSION MAY INTERMITTENTLY EXHIBIT A SLIGHT CLUNK ON A 3-2 DOWNSHIFT DURING COASTDOWN/TIP-IN UNDER NORMAL DRIVING CONDITIONS. THIS IS A NORMAL CHARACTERISTIC, SO DO NOT ATTEMPT REPAIR.
EFFECTIVE DATE: 10/21/2004
After the previous message came out, then this TSB came out.
TSB 05-10-12 HARSH 3-2 DOWNSHIFT BETWEEN 17-25 MPH - NO DTCS - 4R75E AUTOMATIC TRANSMISSION - VEHICLES BUILT BEFORE 4/20/2005 ISSUE: SOME 20005 F-150 AND 2006 MARK LT VEHICLES BUILT BEFORE 4/20/2005, EQUIPPED WITH THE 5.4L ENGINE AND 4R75E AUTOMATIC TRANSMISSION, MAY EXHIBIT A HARSH 3-2 DOWNSHIFT BETWEEN 17-25 MPH WITH NO DIAGNOSTIC TROUBLE CODE (DTC), AND A DRIVELINE CLUNK BETWEEN 40-50 MPH.
ACTION: REPROGRAM THE POWERTRAIN CONTROL MODULE (PCM) TO THE LATEST CALIBRATION USING WDS RELEASE B37.4 OR HIGHER.....
The issue if it is a 3-2 downshift is the intermediate one way clutch going from over-running to holding and causing this clunk. You may also want to disable overdrive prior to down shifting throttle forced to see if the concern stops indicating its a 4-2 downshift and a overdrive band issue.
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