Laminate discs and seals to rebuild leaking or stuck pressure switches on the GM 6L80 control solenoid body instead of replacing the whole TEHCM.
When a Silverado, Sierra, Tahoe, Yukon, Escalade, Enclave or Traverse with a GM six-speed sets pressure switch codes like P0842, P0872 or P0877, shifts hard or drops into limp mode, the problem is often a few cents worth of film and rubber inside the TEHCM, not the module's electronics. This is the bulk refill: 40 laminate diaphragm discs and 40 seals, crossing to 124740-30K, S124442RK-1 and 124740-70K. It suits a shop that rebuilds TEHCMs regularly, or a DIYer who already owns the installer tools and wants spares for more than one module.
The TEHCM bolts to the bottom of the valve body and combines the transmission computer, the solenoids and a row of fluid pressure switches. Sonnax explains that each switch is fed from one of the clutch regulator valves, and the open or closed state of the switches tells the computer which gear is actually engaged. The computer also times how quickly each switch moves to judge clutch apply time, which is how it tracks clutch wear and adapts shifts. The switches are normally closed. Oil pressure pushes a thin film down onto a piston and disc and separates the contacts. That film and the seal under it are the parts in this kit.
Watch the switch states live on a scan tool that can display them; a switch that never changes, or changes in the wrong range, is the suspect. Then check the circuit and connector with a meter. This kit fixes the mechanical disc and seal only, so a switch with an open or shorted circuit will not be cured by new parts. Also confirm line pressure is in range, because a switch that never sees pressure sets the same code. Our 6L80 Escalade shift problems guide covers why many trucks get a TEHCM they did not need, and the 6L80 Camaro shift problems guide walks through the pressure test and adapt reset.
Listed for the GM 6L45, 6L50, 6L80 and 6L90 rear-drive six-speeds and the Gen 1 6T70 and 6T75 front-drive units. Sonnax notes that GM began dropping these switches from the 6T70 series in the 2013 model year, and the Gen 2 parts do not interchange, so a later 6T unit may have no switches to rebuild. Open your TEHCM and compare its switches to the kit, or send us your year and VIN. More parts for this transmission are on our 6L80 parts page.
No tools are included. The disc and seal are thin and must sit perfectly flat, so use a dedicated installer such as the 124740-TL30 pressure switch install tool kit. Drain the pan, remove the filter and TEHCM, and work on a clean bench, since debris is what killed the old switches. Remove the switch retainer, pull the old disc and seal, clean and dry the bore, seat the new seal and disc with the installer, and restake or reseat the retainer so it holds tight. Reinstall the TEHCM to service manual torque with a new filter, refill with Dexron VI, clear codes and reset transmission adapts with a scan tool. If the valve body itself is worn, a 6L80 valve body rebuild kit belongs on the same job.
| Includes | 40 laminate pressure switch discs, 40 seals |
| Cross reference | 124740-30K, S124442RK-1, 124740-70K |
| Fits | GM 6L45, 6L50, 6L80, 6L90, 6T70, 6T75 |
| Component | TEHCM / control solenoid valve body pressure switches |
| Not included | Installer tool, TEHCM electronics |
| Prime | Yes |
Several. Each module has a handful of switches, so 40 sets covers multiple rebuilds plus spares for a disc that gets creased during handling.
No. It is discs and seals only. Use a pressure switch installer kit such as the 124740-TL30 to seat the parts flat without damaging the film.
Only if the cause is a torn or leaking disc or seal. Check the switch circuit and connector with a meter and confirm line pressure first. An open or shorted switch circuit is not fixed by this kit.
It fits Gen 1 6T70 and 6T75 units that have the pressure switches. GM began removing the switches from the 6T70 series in 2013, so open the TEHCM and look before ordering.
Yes. Clear the codes and reset the transmission adapts so the computer relearns clutch timing with the repaired switches. Refill with Dexron VI and set the level at the check plug hot.
