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95 ford explorer dtc 646 possible fixes?
Sent to Car Experts November 29 09:40 AM

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1995 Ford explorer 4.0

Already Tried:
ford bulletin 97-17-24 replaced intermediate servo piston and overdrive servo piston. tested tps no problem found.4r55e transmission

Customer (name blocked for privacy)
Status:  Closed   Value: $5
Info Request
November 29 2:48 PM (5 hours and 8 minutes and 5 seconds later)
         
REPLIED to Info RequestCheck Mark
646 indicates an improper gear ratio was obtained for second gear. Did you readjust the bands after replacing the servos? Were they damaged??

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Gene -- Auto Service Technician -- 99% Positive Feedback on 501 Car Accepts
ASE Master w/L1 Advanced Engine Performance, Ford Trans Tech/SMT, Toyota, Mitsubishi,Hyundai Tech.
Reply
November 29 4:06 PM (1 hour and 17 minutes and 44 seconds later)
         
Reply to Gene's Post: THE SERVO PISTONS WERE HARD AT THE LIP SEAL SO YES THEY WERE BAD INSTALLED NEW ONES PER THE BULLITEN AND READJUSTED BOTH BANDS. ALSO CHECKED SHIFT SOL. AND 2ND GEAR SOL. VALVE IN THE VALVE BODY. SOL. RESISTANCE WAS IN SPEC. AND VALVE WAS NOT STUCK. I SWAPED THE 2ND GEAR SHIFT SOL. WITH THE 3RD GEAR SOL. TO SEE IF THE PROBLEM WOULD CHANGE BUT DID NOT. SAME RESULT TRANS WILL NOT SHIFT OUT OF FIRST GEAR UNLESS I LIFT THE THROTTLE AND THEN IT SHIFTS. STILL CODE 646
Customer (name blocked for privacy)
Answer
November 29 6:57 PM (2 hours and 50 minutes and 51 seconds later)
         
ACCEPTEDCheck Mark
As long as the band adjusted/was able to torque down and back off, the band is not broken, I would suspect a problem with the valve body gasket being blown. Drive the truck in the manual 1st gear range and wind it up to 15-20 mph. Let it coast,you should feel engine braking/the truck hold back. If it doesnt,the valve body gasket is blown at the low reverse servo piston(rear)of the valve body or possibly along the left side above the shift solenoid. Common problem, they also have some other updates for the valve body depending on the production date of the vehicle.

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Gene -- Auto Service Technician -- 99% Positive Feedback on 501 Car Accepts
ASE Master w/L1 Advanced Engine Performance, Ford Trans Tech/SMT, Toyota, Mitsubishi,Hyundai Tech.
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