The GM 8-speed 8L90 transmission is incredibly complex, and was the first gearbox of its kind to come from General Motors. As you might imagine, the 8L90 valve body is equally complex, and uses a number of innovative solutions to shift through all of those gears. For example, there are a total of nine 8L90 solenoids. Seven of which are variable force pressure control solenoids, and two on/off solenoids. Although some of them seem identical, replacing a 8L90 solenoid or the entire valve body itself, will require performing the adaptive relearn process so the computer knows what’s going on inside of the gearbox. Each solenoid controls a separate component inside the transmission, so failure to do the adaptive learning process will result in a number of 8L90 valve body related problems.
What Transmission Do I Have?
Now let’s look at some of the most common 8L90 valve body problems and find out what you can do about them.
8L90 Valve Body Applications
| Model |
|---|
| Cadillac Escalade |
| Chevy Camaro |
| Chevy Colorado |
| Chevy Express 1500 |
| Chevy Express 2500 |
| Chevy Express 3500 |
| Chevy Express 4500 |
| GMC Canyon |
| GMC Savanna 1500 |
| GMC Savanna 2500 |
| GMC Savanna 3500 |
| GMC Yukon |
8L90 Valve Body Diagnostic Trouble Codes | DTC
| Trouble Code | Description |
|---|---|
| P0711 | Transmission Fluid Temperature Sensor Circuit Range/Performance |
| P0712 | Transmission Fluid Temperature Sensor Circuit Low Input |
| P0713 | Transmission Fluid Temperature Sensor Circuit High Input |
| P0716 | Input/Turbine Speed Sensor Circuit Range/Performance |
| P0717 | Input/Turbine Speed Sensor Circuit No Signal |
| P0722 | Output Speed Sensor Circuit No Signal |
| P0723 | Output Speed Sensor Circuit Intermittent |
| P0746 | Pressure Control Solenoid 'A' Performance or Stuck Off |
| P0747 | Pressure Control Solenoid 'A' Stuck On |
| P0776 | Pressure Control Solenoid 'B' Performance or Stuck Off |
| P0777 | Pressure Control Solenoid 'B' Stuck On |
| P0796 | Pressure Control Solenoid 'C' Performance or Stuck off |
| P0797 | Pressure Control Solenoid 'C' Stuck On |
| P0826 | Up and Down Shift Switch Circuit |
| P0851 | Park/Neutral Switch Input Circuit Low |
| P0960 | Pressure Control Solenoid A Control Circuit/Open |
| P0962 | Pressure Control Solenoid A Control Circuit Low |
| P0963 | Pressure Control Solenoid A Control Circuit High |
| P0964 | Pressure Control Solenoid B Control Circuit/Open |
| P0966 | Pressure Control Solenoid B Control Circuit Low |
| P0967 | Pressure Control Solenoid B Control Circuit High |
| P0970 | Pressure Control Solenoid C Control Circuit Low |
| P0971 | Pressure Control Solenoid C Control Circuit High |
8L90 Valve Body Technical Service Bulletins | TSBs
08-07-30-035D: INFORMATION ON WATER OR ETHYLENE GLYCOL IN TRANSMISSION FLUID
2015 > GM vehicles equipped with the 8L90 transmission
Problem – Water or ethylene glycol can contaminate the ATF in a number of different ways, including a leaking transmission oil cooler inside the radiator. This problem often exhibits with a shudder during gear changes, especially when the torque converter clutch engages. Other symptoms of this problem include ATF blowing out of the transmission vent tube.
Solution – Given that contaminated ATF can damage everything from the clutches and valve body, to rust and corrosion on the metal parts, the entire 8L90 transmission and 8L90 valve body will have to be completely rebuilt or replaced with a remanufactured unit.
8L90 Valve Body Problems
Given that it was the first 8-speed automatic transmission to come from General Motors, it’s no surprise that there were numerous 8L90 transmission problems and 8L90 valve body problems. Some of these triggered an 8L90 transmission class action lawsuit, alleging that GM knowingly built and sold a defective transmission. That GM 8-speed transmission lawsuit was eventually dismissed. However the problems that led to it certainly were not as easily dispatched.
What Transmission Do I Have?
One of the main problems was erratic shifting issues that caused clutch material and other metal shavings to get circulated throughout the transmission. This debris would eventually wind up in the 8L90 valve body and cause catastrophic failure. Naturally, the only solution for such a situation is to install a remanufactured 8L90 valve body, along with replacing any damaged components that led to the failure in the first place.
