F-150/F-250: Why is My Transmission Shifting Too Hard?

A transmission that is shifting too hard generally has a problem with its fluid pressure. When that pressure is too high, shift can happen erratically and forcefully.

By Brett Foote - December 1, 2014

This article applies to...

Modern transmissions shift so softly and smoothly that we often forget they are even working. A hard shifting transmission is a symptom of several other distinct issues. Follow our handy step-by-step guide below to diagnose and repair the problem!

Step 1 - Determine which transmission the truck has

Check the sticker on the driver's side door jamb to identify the truck's transmission. The transmission field is circled in the figure below. Decipher the code using the following table.

Figure 1. All Ford trucks come with an info sticker in the driver side door jamb.
F-150 Transmission CodesF-250 Super Duty Transmission Codes
Q - 4-speed automatic, 4R75E 2 - 5-speed manual, TREMEC, TR4050
6 - 6-speed automatic, 6R80 P - 6-speed automatic, 6R140
Q - 4-speed automatic, 4R75E (F-150/Mark LT) T - 5-speed automatic, 5R110W
M - 5-speed manual, M5R2-C (F-150) W - 6-speed automatic, diesel, 6R140
F - 4-speed automatic, 4R75E (Mark LT) 5 - 6-speed manual, Dana, Z/F S6-650
A - 4-speed automatic, 4R70E (F-150) 7 - 6-speed manual, Dana, Z/F M6HD-W
B - 5-speed automatic, Hi-Torque diesel, 5R110W
T - 5-speed automatic, 5R110W

Step 2 - Check for transmission codes

For a 4R75E Transmission

Turn your truck off and look at the instrument panel. Keep your OBD II code reader handy.

  • If the O/D light is flashing, go to the O/D light diagnostic.
  • If you're getting a trans fault error, pull codes with your reader to see what's wrong.

Related Article:

DTCs

Diagnostic Trouble CodeFailing ComponentCause for CodeSymptoms
P0102, P0103, P1100, P1101 Mass Air Flow Sensor (MAF) The Mass Air Flow sensor in your truck isn't working correctly, causing the transmission to misbehave Incorrect reading from the MAF could result in all sorts of transmission weirdness. Soft shifting, hard shifting, odd shift points, etc.
P0705, P0708 Transmission Range sensor (TR) TR Circuit failure Harsh shifts. Stuck in D or 2.
P0712, P0713 Transmission Fluid Temperature (TFT) 712 = sensor circuit grounded
713 = sensor circuit open
Hard shifting
P0715, P0717, P0718 Turbine Shaft Speed Sensor (TSS) Signal from TSS dead, intermittent, on noisy Hard shifting
P0720, P0721, P0722 Output Shaft Sensor (OSS) Signal from OSS dead, intermittent, on noisy Hard shifting, abnormal shifting, slipping
P0731, P0732, P0733, P0734 Shift Solenoid A/B Shift Solenoid A/B failure or internal transmission failure No gear in 1, 2, 3, 4 (respectively)
P1714, P1715 Shift Solenoid A/B 4 = SSA mechanical failure
5 = SSB mechanical failure
Solenoid is either stuck closed or open due to a physical failure. Replace them.
P0740, P0743 Torque Converter Clutch (TCC) TCC solenoid is failing or TCC is slipping excessively Transmission Warning light may flash. Engine might stall in D at low speeds or never engage.
P0741 TCC TCC is slipping excessively due to internal, mechanical issues Slipping transmission
P0748, P0963 Electronic Pressure Control sensor (EPC) EPC solenoid short Limited torque, slipping transmission, or harsh shifting if the circuit is stuck open.
P1728 Transmission Slip Error Truck computer senses excessive slipping Transmission is slipping, TCC operating erratically
P1740 TCC TCC solenoid mechanical failure Stalls in D and 2, or torque converter never applies
P1741 TCC Excessive TCC engagement issue Engine rushing/oscillation in 3rd gear. TCC is slipping
P1742, P1743 TCC, internal issues TCC solenoid has failed, or the TCC itself has failed Hard shifting
P1744 TCC Truck senses extra slippage from the TCC Slipping transmission
P0962, P1747 EPC EPC solenoid malfunctioning (short circuit) Minimum EPC pressure, reduced torque, slippage
P1760 EPC EPC solenoid signal dead Reduction in torque

6R80 DTCs for Slipping Transmission

Diagnostic Trouble CodeFailing ComponentCause for CodeSymptoms
P0715, P0716, P0717 Turbine Shaft Speed Sensor (TSS) short circuit, noisy or lost signal, no signal May cause Check Engine Light, will trigger Transmission Warning Light, inability to shift from 3rd, hard shifts, "slipping" transmission/No TCC engagement
P0720, P0721, P0722, P0723 OSS Sensor short circuit, noisy or lost signal, no signal Check Engine Light, hard shifts, "slipping" transmission/No TCC engagement
P0731, P0732, P0733, P0734, P0735, P0729 Transmission error 1 = 1st gear
2 = 2nd gear
3 = 3rd gear
4 = 4th gear
5 = 5th gear
29 = 6th gear
Missing gear. Engine flare in missed gear, hard shifts, TCIL
P0740, 1 TCC circuit failure, circuit open Slipping shifts, harsh shifts, no shifts, Triggers "Limp home mode," Transmission Warning light, and maybe Check Engine Light

P0781, P0782, P0783, P0784, P0729

Shift Errors 1 = D1-2
2 = D2-3
3 = D3-4
4 = D4-5
29 = D5-6


These codes indicate shifting errors. You may be stuck in gear and have strange shifting from one gear to another.
P0960, P0961, P0962, P0963 Line Pressure Control Solenoid The line pressure control solenoid is shorting out Hard shifts, Transmission Warning Message

Step 3 - Test EPC pressure line

If pressure readings are off, follow the chart below to help pinpoint the failing component in your transmission.

Related Article:

  • How to Test Transmission Line Pressure - Ford-Trucks.com

The next steps require you to drop the transmission pan and examine the valve body of your truck. This is a considerably more involved process than that of anything in the last steps, and taking the truck to a mechanic is recommended. However, if you're familiar with working on cars and aren't worried about potentially damaging your transmission further, please continue.

Step 4 - Check 1-2 accumulator

Checking the accumulator in the transmission valve body is a slightly more involved task than replacing the transmission fluid. Taking the truck to the mechanic might be an easier option at this point. Still, changing the spring in this accumulator is one of the ways performance tuners speed up shifts in automatic transmissions.

  1. Lift the truck on jack stands with the transmission in neutral.
  2. Drain transmission fluid and remove pan and filter.
  3. Compress the accumulator piston and remove the retainer ring. Use tweezers to get the ring out without damaging it or the metal sleeve it fits into.
  • F-150 4R75E Valve Body
    Figure 2. The 1-2 accumulator piston is circled in red.
  • Figure 3. F-150 accumulator 1 diagram.

You will now need to break the accumulator down and check the parts:

  1. Remove the cover.
  2. Remove the inner and outer springs.
  3. Remove the piston.
  4. Remove the upper spring.
  • If any of these are cracked, broken, warped, or showing any kind of failure, replace them. Then make sure the cylinder where the piston came from is free of damage and metal particles.
Figure 4. Accumulator 1-2 piston removed from valve body.

Step 5 - Check valve body

Remove the transmission pan, and drop the valve body. Examine the main pressure regulator valve.

  • If stuck or otherwise damaged, replace. We recommend you do this only if you're familiar with transmission valve bodies. Otherwise, take it to the shop.
Figure 5. A bad pressure regulator valve can cause line pressures in your valve body to run high or low. Both will result in undesirable shifting behavior.

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