Sonnax GM 8L45 Transmission

Valve Body (View Valve Body Layout Diagram)

1-3-5-6-7 Accumulator Piston Kit 154740-15K

Helps cure:

Clutch slippage
Burnt clutches
Flare shifts
Ratio codes

Bore Sizing Tool 154740-BST11

Bore Sizing Tool 154740-BST13

Clutch Control Valve Vacuum Test Tool Kit 154740-TL11

Tooling:

VACTEST-01K

Converter Feed Limit Valve Kit 154740-19K

Helps cure:

Code P0218
Code P0741
Overheated converter
Inadequate lubrication
Excess converter pressure
High TCC slip RPM

Converter Feed Limit Valve Vacuum Test Tool 154740-TL22

Tooling:

VACTEST-01K

O-Ringed End Plug Kit 154740-17K

Helps cure:

Gear ratio & solenoid codes
Lube failures
Poor lube oil control
Converter concerns
Reduced converter clutch life
TCC apply & release concerns
Burnt converter

O-Ringed Shuttle Valve Kit 154740-30K

Helps cure:

High line pressure
Harsh shifts
Low cooler flow
Loss of lube oil
Overheated transmission & converter

Oversized Converter Feed Limit Valve Kit 154740-22K

Helps cure:

Excess converter pressure
High TCC slip RPM
Code P0218
Code P0741
Overheated converter
Inadequate lubrication

Tooling:

F-154740-TL22
VB-FIX

Oversized S4 Clutch Control Valve Kit 154740-26K

Fits '19-later units only.

Helps cure:

Burnt clutches
Pressure loss
Poor shift quality

Tooling:

F-154740-TL26
VB-FIX

Oversized Signal Accumulator Piston Kit 154740-01K

Helps cure:

Poor shift quality
Low line pressure
No converter apply
Hydraulic-related converter codes
Burnt clutches
Soft shifts

Tooling:

154740-TL

Pressure Regulator & O-Ringed Shuttle Valve Kit 154740-29K

Helps cure:

Low line pressure
Burnt clutches
Harsh shifts
Low cooler flow
Loss of lube oil
Overheated transmission & converter
Soft shifts
High line pressure

Pressure Regulator & Shuttle Valve Kit 154740-02K

Helps cure:

Low line pressure
Burnt clutches
Harsh shifts
Low cooler flow
Loss of lube oil
Overheated transmission & converter
High line pressure
Soft shifts

Pressure Relief Ball Valve Spring 154740-18

Helps cure:

No movement
Damaged valve body casting
Broken parts due to excessive line pressure
Erratic line pressure

S1/S5 Clutch Control Valve Kit 154740-13K

Fits either of 2 locations.

Helps cure:

Burnt clutches
Pressure loss
Poor shift quality

S2/S3/S4/TCC Clutch Control Valve Kit 154740-11K

Fits any of 4 locations, S4 location fits '18-earlier only

Helps cure:

Burnt clutches
Pressure loss
Poor shift quality
Burnt converter
TCC apply & release concerns

S4 Clutch Control Valve Kit 154740-24K

Fits '19-later units only.

Helps cure:

Burnt clutches
Pressure loss
Poor shift quality

Shift Zip Kit® 8L45-8L90-SHIFT-ZIP

For shift-related complaints.

Helps cure:

Poor shift quality
Burnt clutches
Flare shifts
Soft shifts
Clutch slippage
Low line pressure
Ratio codes

Shuttle Valve Kit 154740-09K

Helps cure:

High line pressure
Harsh shifts
Low cooler flow
Loss of lube oil
Overheated transmission & converter

Signal Accumulator Piston Kit 154740-06K

Includes 4 piston sets which fit any of 7 locations.

Helps cure:

Poor shift quality
Low line pressure
No converter apply
Hydraulic-related converter codes
Burnt clutches
Soft shifts

TCC Zip Kit® 8L45-8L90-TCC-ZIP

For converter-related complaints.

Helps cure:

TCC apply & release concerns
Overheated transmission & converter
Loss of cooler flow
Loss of lube oil
Burnt converter
High TCC slip RPM
Code P0218
Code P0741

Other

Tool Kit 154740-TL

Tool Kit F-154740-TL26

Tooling:

VB-FIX

Tool Kit F-154740-TL22

Tooling:

VB-FIX

Tech Resources

April 16, 2024

Watch Out for High Pressure in GM 8L45, 8L90 Valve Bodies

Chris Leach

August 10, 2023

Tips for Success with the GM Transmission Fast Learn Process

Jim Mobley

July 27, 2023

Tips for Tackling 8L45, 8L90 Shift Repairs with Sonnax Signal Accumulator Pistons

Caleb Perham

December 12, 2022

Troubleshooting GM 8L45, 8L90 No Move & No Pressure Conditions

Jim Mobley

December 07, 2022

Stop-Start Accumulators: What You Don't Know CAN Hurt You

Matt Allbert

October 13, 2022

How to Get Started with OE ECU Reprogramming

Jim Mobley

April 06, 2022

Diagnosing the Infamous GM 8L45, 8L90 3-4 Neutral: Check Your Solenoid Wiring Harness Assembly

Jim Mobley

October 01, 2021

GM 8L45, 8L90 Valve Body Layout

April 21, 2021

GM 8L45, 8L90 Vacuum Test Guide

April 21, 2021

Diagnosing 8L45 & 8L90 Shift Complaints: Always Check the VFS Solenoid Circuits

Maura Stafford