10R80 gear ratio errors after rebuild

10R80 gear ratio errors after rebuild

A 2018 F-150 Raptor using a 3.5L EcoBoost in front of a 10R80 transmission developed a noise at the rear of the transmission. The shop eventually diagnosed this as a rear case needle bearing failure. When road tested after repairs, the computer detected gear ratio errors immediately. This took the shop through a time-consuming process before discovering a simple error in the rebuild that caused this problem. 

The 10R80 utilizes four spend sensors, as figures 1 and 2 show. Mike Souza wrote about these speed sensors for Transmission Digest in an excellent January 2019 article entitled “Ford & GM 10R80/10L90 Speed Sensor Functions.” I highly recommend the read as it is quite informative concerning the functions of these internally mounted hall effect sensors. To accompany this article, here is what Ford offers in their functional explanation of these four speed sensors along with a brief explanation of their strategies. 

Figure 1.
Figure 2.

Turbine speed sensor

The TSS sensor is a Hall-effect type sensor that provides a signal to the PCM that changes in frequency as the rotating speed of the planetary carrier No. 2 varies. The PCM compares the TSS sensor signal with the engine speed information to determine the amount of slip occurring in the torque converter. The PCM also compares the TSS sensor signal with the OSS sensor signal to determine the gear ratio provided by the planetary carrier No. 4. The PCM uses the TSS sensor signal as an input for its shift strategies and TCC operation. The PCM also uses the TSS sensor signal for transmission fault detection and diagnostics.

Output speed sensor

The OSS sensor is a Hall-effect type sensor that provides a signal to the PCM that changes in frequency as the rotating speed of the rear planetary carrier No. 4 varies. The PCM also compares the OSS sensor signal with the TSS sensor signal to determine the gear ratio provided by the rear planetary gearset. The PCM uses the OSS sensor signal as an input for its shift strategies and TCC operation. The PCM also uses the OSS sensor signal for transmission fault detection and diagnostics.

Intermediate speed sensors A and B

The Intermediate Speed Sensors A (ISSA) and B (ISSB) are Hall-effect type sensors that provide a signal to the PCM that changes in frequency as the rotating speed of the component being monitored changes. ISSA monitors the speed and rotational direction of ring gear 1 and ISSB monitors the speed and rotational direction of planetary carrier-1/ring gear 4. The intermediate speed sensors are used to monitor clutch states for transmission fault detection and diagnostics.

Read more stories from our Technically Speaking columns here.

The error made by the shop could easily happen to anyone without reference materials to refer to. Many techs have learned to take pictures with their cell phones when working on a unit for the first time to keep them out of trouble. In this case, the unit was disassembled and repaired without taking any pictures. So, when the tech installed the speed sensors into the case, he accidently installed the Output Speed Sensor (OSS) into the Intermediate Speed Sensors B (ISSB) location and the ISSB was placed into the OSS location (figure 3). This caused the harnesses to be inserted into the wrong connector (figure 4). In essence, these two sensors became cross-connected. When these sensors are placed into their correct positions, they cannot be cross-connected due to the configuration of the connector ends. 

Figure 3.
Figure 4.

Here is a list of the gear ratio DTCs that this 10R80 can produce, as well as speed sensor performance codes. Be careful with gear ratio code for seventh and ninth gear if you are dyslexic!

  • P0731 – 1st gear ratio error  
  • P0732 – 2nd gear ratio error  
  • P0733 – 3rd gear ratio error  
  • P0734 – 4th gear ratio error  
  • P0735 – 5th gear ratio error  
  • P0736 – Reverse gear ratio error  
  • P0729 – 6th gear ratio error  
  • P076F – 7th gear ratio error  
  • P07D9 – 8th gear ratio error  
  • P07F6 – 9th gear ratio error  
  • P07F7 – 10th gear ratio error  
  • P0792 – ISSA range/performance fault
  • P0716 – TSS range/performance fault 
  • P2746 – ISSB range/performance fault 
  • P0721 – OSS range/performance fault

Was this content valuable?

Thanks for your feedback!

You May Also Like

The importance of the follow-up road test after transmission replacement

A 2002 Lexus RX300 equipped with a 3.0-liter V6 engine and U140F transmission was brought into our facility with a few concerns. The customer said that “it has a leak, a grinding noise when taking off from a stop, and it just doesn’t seem to shift right.” They went on to tell us that this

RR Tech Feature Oct

A 2002 Lexus RX300 equipped with a 3.0-liter V6 engine and U140F transmission was brought into our facility with a few concerns. The customer said that “it has a leak, a grinding noise when taking off from a stop, and it just doesn’t seem to shift right.”

Tips and tricks for Chrysler switch valve plug testing

As technicians, we are often faced with build issues that can sometimes be frustrating at first. But with a little ingenuity, these frustrations can be turned around and made simple. Related Articles – GM 8L90 #7 Check-ball: The overheat that saved the day – ETE Reman: Ever expanding – Shift Pointers: Nissan’s no throttle response

tascfeature-1400
GM 8L90 #7 Check-ball: The overheat that saved the day

Beginning in October of 2015, GM removed the #7 Check-ball from the solenoid valve control body in the 8L90 transmission (see Figure 1). This was done in conjunction with the elimination of the Lube Override Enable Valve from the upper valve body as shown in Figure 2. Related Articles – Jatco/Nissan JF011E critical wear areas

Shift Pointers: Nissan’s no throttle response

Nissan vehicles using continuously variable transmissions (CVTs) are notorious for defaulting to a no throttle response when the vehicle is engaged into gear. There are several malfunctions that can cause this protective failsafe feature to be initiated. A brake switch (stop lamp switch) stuck on, a double-footed driver, blown or incorrect brake bulbs, and wheel

Jatco/Nissan JF011E critical wear areas and vacuum test locations

Sonnax has provided the following guide on critical wear areas and vacuum test locations for the Jatco/Nissan JF011E. Technicians working on these models should find this guide helpful. (Ed. Note: This is an extended version of the guide found in our September issue, with three additional pages). Related Articles – Podcast: Talking CVTs with Transtar,

Other Posts

Raybestos offers high carbon torque converter wafer for Ford 10R80

Raybestos has begun offering a high carbon torque converter wafer for Ford 10R80 transmissions. Related Articles – Gray Tools releases insulated socket sets – RatioTek introduces new tuner kit for Ram trucks – Sonnax highlights GM 4L heavy-duty input shafts According to the company, it is a bond-in solution that flexes and conforms to fit

Raybestos-Ford-10R80-friction-wafer-1400
Tips for success with the GM transmission fast learn process

This article is about failure, something we all experience from time to time. If you are attempting to perform a fast learn process on a GM eight-, nine-, or 10-speed transmission, you may have that temporary feeling of failure, as this process can bring on frustration quickly. Let’s talk about what the fast learn process

tascFeaturefast-1400
Shift pointers: Tricky sensor situations

Sometimes you’re the windshield and sometimes you’re the bug—a phrase many of us have heard and experienced. It’s inevitable. The idea is to be the windshield as much as possible. Shane from Cottman Transmissions had a helluva day but in the end, he was the windshield. Related Articles – CVT maintenance basics – Mercedes-Benz 722.9

Look for the little details: Three transmission repair case studies

Below are three examples of trucks that came into transmission shops, yet either did not have a transmission problem, or had a simpler issue than it originally seemed. Read on for the stories. Related Articles – Infiniti G37 RE7R01A chassis codes set – Honda Accord BB7A six-speed: P2720 code set after collision – Troubleshooting RFE

techspeakfeature-1400