Replaces the worn pressure regulator valve in GM 6L45, 6L50, 6L80 and 6L90 valve bodies to restore line pressure and cure low-pressure slip codes like P0776.
A GM six-speed that slips on the 1-2 when hot, slams into gear cold, runs hot on a long tow or sets pressure control and ratio codes is often losing control of line pressure at one bore. This kit is for owners and shops chasing that problem on a 6L80 or 6L90 in a 2006-up Silverado, Sierra, Tahoe, Yukon, Escalade, Camaro or Corvette, and on the lighter 6L45 and 6L50 used in Cadillac, Pontiac and Holden cars. It replaces the worn pressure regulator valve with a correctly sized valve so the bore holds pressure again.
The pump puts out far more oil than the transmission needs. The pressure regulator valve decides how much of it becomes mainline pressure and how much is sent on to feed the converter and the cooler. The TEHCM raises or lowers that pressure through a solenoid and boost valve, but the regulator valve does the actual work. On this family the main pressure regulator valve lives in the pump, not the valve body, which Sonnax points out on its 6L80 valve body page: wear in the regulator bore or its boost valve cannot be fixed by swapping the valve body. Sonnax research found two wear spots. When the balance end wears into the casting, line pressure runs high, shifts get harsh and the unit overheats because cooler and converter flow drop. When the outboard spool wears, converter feed falls and line pressure runs low. With both ends worn, pressure becomes erratic.
Put a gauge on the line pressure port and compare actual pressure to what the scan tool says the TEHCM is commanding, at idle and as RPM rises. Sonnax notes that line pressure stuck around 60 to 68 psi with no rise usually points to a line pressure solenoid stuck in exhaust in the TEHCM, and pressure under about 30 psi at idle can come from a missing boost valve retaining pin, so check those first. Our 6L80 pump failure symptoms guide explains how pump problems show up on the gauge, and 6L80 common problems and fixes covers the valve body and TEHCM failures with similar complaints. On the bench, a vacuum test of the regulator bore is the most direct check for wear.
The kit is listed for the GM 6L45, 6L50, 6L80 and 6L90 six-speed rear-wheel-drive automatics from 2006 on, across Chevrolet, GMC, Cadillac, Hummer, Holden and Pontiac. The listing describes it as covering the pressure regulator valve along with solenoid regulator valve parts; note that the solenoid regulator, also called the actuator feed limit valve, sits in the valve body while the main regulator sits in the pump, so match the kit contents to the bore you are repairing. If you need help confirming which unit you have, check the RPO code (MYA, MYB, MYC or MYD) or send your year and VIN. More parts for this unit are on our 6L80 transmission parts page.
Because the regulator lives in the pump, plan on pulling the transmission and removing the pump from the case. Remove the retaining pin, sleeve, spring and valve in order, lay them out the way they came out, and clean the bore. Inspect the boost valve and its sleeve, since a worn boost valve undoes a new regulator. Lube the new valve with clean ATF, confirm it moves freely through its full travel, reinstall and retest pressure. If the pump body itself is damaged, a complete 6L80 pump is the better repair, and a unit with burnt clutches needs a 6L80E master rebuild kit as well. Refill with Dexron VI and reset adapts after the repair.
| Fits | GM 6L45, 6L50, 6L80, 6L90 (2006 and up) |
| Applications | Chevy, GMC, Cadillac, Hummer, Holden, Pontiac 6-speed RWD |
| Corrects codes | P0729, P0731-P0735, P0751, P0752, P0756, P0757, P0761, P0762, P0776, P0777 |
| Function | Restores line pressure at the worn pressure regulator valve bore |
| Install | Valve-body-out bench install, no case machining |
| Ships from | USA |
The main pressure regulator valve is in the pump, along with its boost valve and the TCC control valve. That is why replacing the valve body does not cure line pressure problems caused by a worn regulator bore.
For the main regulator, no. The pump has to come out of the case, which means removing the transmission. Valve body parts such as the actuator feed limit valve can be serviced with the pan and valve body off.
Yes, the kit is listed for the 6L45, 6L50, 6L80 and 6L90. Confirm the RPO code on your vehicle before ordering.
A worn regulator bore usually gives high, low or erratic line pressure that still responds somewhat to commanded changes. Pressure stuck at about 60 to 68 psi with no rise at all is more typical of a TEHCM line pressure solenoid fault.
GM specifies Dexron VI for the 6L family. Many of these vehicles have no dipstick, so follow the check procedure at operating temperature, then reset transmission adapts.
