One thing about this industry is that change is a constant thing. In the ATRA seminars over the last few years, we have included detailed information regarding the processes that need to be followed when servicing the GM 8, 9 and 10 speed applications. As we have seen, some technicians that have not attended the seminars have struggled to get the units to shift correctly.
The 8, 9 and 10 speed applications utilize a valve body that is flow tested at the manufacturing plant. The flow numbers represent the flow characteristics of the valve body and its solenoids. Those valve body flow numbers are represented by a number known as the PUN (Part Unique Number). The PUN number is lasered into the valve body casting along with a “QR” (Quick Response) Data Matrix label.
As the transmission progresses down the line, a laser reads and records the PUN. The PUN number is then used to develop the TUN (Transmission Unique Number) which is then represented as a label on the outside of the transmission case. When the vehicle is assembled, the plant system knows the TUN, which means the system also knows the valve body PUN. That valve body flow information is used to select the correct transmission calibration which is loaded at the end of the assembly line. When the calibration is loaded, the PUN/TUN are then married to the vehicles VIN.
Repairs or replacement of the transmission require that the PUN or TUN be relearned by the TCM. Instances where the TUN or PUN need to be relearned include:
- Replacing the transmission — The TUN will need to be relearned.
- Replacing the TCM or installing updated calibration in the TCM — The TUN will need to be relearned.
- The valve body was replaced — The PUN will need to be relearned.
- On any 8, 9 or 10 speed application two things are critical:
- If the valve body, transmission or TCM were replaced the TUN or PUN will need to be relearned which will “marry” the new components flow characteristics to the TCM calibration. If you fail to do so, the TCM will not know that those components were serviced so it may select the incorrect pressure values for the components installed.
- The TUN and PUN on your application should always be recorded on your repair order. This includes the new PUN/TUN numbers for the components that were replaced. This step will save you a lot of headaches if you need access to the numbers later on.
PUN UPDATE
Starting in mid 2019, the process for etching the PUN number onto the valve body changed on some applications such as the 9T45, 9T50, 9T60, 9T65 (RPO’s M3W, M3T, M3G, M3D, M3H, M3V, M3U, M3E).
The PUN prior to this change was a 16-digit number. It is now represented by an 11-digit number. The GM SPS reprograming system will request a 16-digit PUN which means you will likely be stumped when it comes to how to locate a 16-digit number when only an 11-digit number is present.
Those of you that have attended the ATRA seminar the past 3 years will remember that we discussed that GM no longer uses an RPO sticker and now the RPO codes are included in a QR label located on the driver’s door B pillar. Using a smart phone and a QR label reader app you can locate the RPO information by simply shooting the label while the APP is open on your phone.
The VIN, RPO’s and other pertinent information is then displayed on your phone. The 11-digit PUN missing information (plant and build date info) can be converted over to a 16-digit PUN with the use of your smart phone and your QR reader app. Simply shoot the QR label on the valve body to display the full PUN. If for some reason you are struggling to get the information, you can try plugging any of the following 5-digit values into the front of the 11-digit PUN located on the valve body, WL0Y9, WL0Y0, WL4P9, WL4P0. Once you get the 16-digit code the information can be plugged into the GM SPS system and the updated PUN will then be married to the TUN and the vehicle VIN.
As we discussed earlier, times are changing and so is this industry. You now need to know more than ever before. Until next time remember “The man on the top of the mountain didn’t fall there”.
