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

You May Also Like

Ford 8F24 mechanical diode failure

Mechanical diode failure in automatic transmissions is not uncommon. As far back as the AODE/4R70 shops have seen this type of failure. In April 2022 an article was published in Transmission Digest called, “The ins and outs of the Hydraulic Selectable One-Way Clutch (SOWC).” This article provided photos of the type of damage this style

Tech-Speak-April-Figure-1-1400

Mechanical diode failure in automatic transmissions is not uncommon. As far back as the AODE/4R70 shops have seen this type of failure. In April 2022 an article was published in Transmission Digest called, “The ins and outs of the Hydraulic Selectable One-Way Clutch (SOWC).” This article provided photos of the type of damage this style diode is susceptible to in 9T50 and 8F35 transmissions.

Ford 8F35 maintenance tips: Planetary failure and no-pressure conditions

Our shop has had several vehicles come in with the Ford 8F35 transmission having planetary failure. Apparently, there was a run where the pinion needle bearings had a hardness problem (see Figure 1). Related Articles – Back with force: ATSG is back in full swing to educate the transmission industry – Don’t fear customer complaints about

Figure 12.
Don’t fear customer complaints about CVTs

Continuously Variable Transmissions, or CVTs, are more common than you think. Audi, Subaru, Nissan, Ford, GM and many other automakers use CVT transmissions in cars and SUVs. There is no way to avoid them. Chances are there is one in your shop right now. Related Articles – Powertrain industry directory and buyer’s guide 2024 –

CVT-Transmission-2
Shift Pointers: A Chrysler 300 no-shift complaint

The case study has to do with a 2009 Chrysler 300 C 5.7L Nag1 RWD with 71,923 miles on it (see Figure 1, above). Related Articles – Shift of the shaft: Diagnosing Chrysler 48RE manual shaft issues – Sometimes, a diagnostic code is all you need – 10L80 and 10R80 pump gear differences It is

A guide to common GM, Ford and Nissan programming issues

One of the most common complaints I hear from shops when trying to install a new GM TCM is, “The module will not communicate.” While that might be partially true, by design they won’t communicate until they are programmed. If programming fails, there will be an “E” code set which will help you get to

Other Posts

Alto introduces Ford 10R series cartridge filter

Alto has introduced a new auxiliary pump cartridge filter for Ford 10R60 and 10R80 transmissions. The filter (part no. 242942) fits model years 2017 and on. Related Articles – Schaeffler releases TorCon 6L80 torque converter – American Powertrain adds GearStar automatic transmissions for Ford, Chevy, Mopar – PRT launches 59 new complete strut assemblies

Alto-242942_-1400
Going the extra mile: Proving your transmission repair suspicions

A 2003 Honda Pilot with a five-speed three-shaft transmission came into our shop with a customer concern that the vehicle had no power, and the “D” light was flashing. I first did a scan for codes to see what it came up with, and the scan tool returned four DTCs: P1298 (ELD voltage high), P0135 (H02S

RRfeature-1400
Diagnosing Ford 10R60, 10R80 and 10R140 series speed sensor issues

Ford 10-speed 10R series transmissions utilize four two-wire, Hall-effect sensors — TSS, ISSA, ISSB and OSS — for providing speed signals to PCM or TCM. They are supplied nine volts by a PCM or TCM and assist in the control of clutch apply/release timing that is used in determining shift quality, including TCC. Related Articles

Jatco JF613E transmission quick reference material

For those working on the Jatco JR613E transmission, a widespread transmission with plenty of applications, the following should be a helpful guide. Related Articles – Outgrowing the walls: The story of EVT Transmission Parts – Spotting different 68RFE designs through the years to avoid issues – Valve body and component suppliers: A comprehensive list Domestic