THM 4T65-E - SOFT 1-2 SHIFT OR DELAY TO REVERSE (MAY STORE DTC 1811)

COMPLAINT: Some General Motors vehicles equipped with the THM 4T65-E transaxle, may exhibit a soft 1-2 upshift and/or a delay when the selector lever is placed into reverse.  These conditions may also set Diagnostic Trouble Code 1811, which is "Maximum Adapt" and "Long Shift".

CAUSE: The cause may be, a defective Pressure Control Solenoid (PCS), and/or a worn line boost valve and sleeve assembly in the valve body, creating less than desired line pressure rise.Find more obd2 scanner from www.obddeal.com.

CORRECTION: Replace the Pressure Control Solenoid with the updated PCS, available from OEM under part number 10478146.  Before installing the new PCS, turn the adjusting screw on the end of the solenoid in exactly 1/8 turn, as shown in Figure 1.
Inspect and replace as necessary, the boost valve and sleeve assembly located in the valve body, in the location shown in Figure 2.  This valve train is available from Sonnax®, under part number 84754-30K, and is not yet available from OEM except in a complete valve body assembly.

SERVICE INFORMATION:
Pressure Control Solenoid (New Design From OEM) ........................................ 10478146
Boost Valve and Sleeve Kit (Sonnax® Part No.) ........................................... 847554-30K
Some hot car tools like X431 Diagun and AD900 are also very helpful.

 301   CONTROL VALVE BODY
 302   LINE BOOST VALVE AND BUSHING RETAINER
 303   LINE BOOST VALVE BORE PLUG
 304   LINE BOOST VALVE
 305   TCC PWM SOLENOID "O" RING SEAL
 306   TCC PWM SOLENOID "O" RING SEAL
 307   PRESSURE CONTROL SOLENOID "O" RING SEAL
 309   REVERSE BOOST VALVE BUSHING
 310   REVERSE BOOST VALVE
 311   PRESSURE REGULATOR VALVE OUTER SPRING
 312   PRESSURE REGULATOR VALVE INNER SPRING
 313   PRESSURE REGULATOR VALVE
314D  1-2, 3-4 SHIFT SOLENOID RETAINER
314E   PRESSURE CONTROL SOLENOID RETAINER
314F   TCC PWM SOLENOID RETAINER
314G  TCC REGULATOR APPLY VALVE BORE PLUG RETAINER
315A  1-2, 3-4 SHIFT SOLENOID ASSEMBLY
316A  1-2, 3-4 SHIFT SOLENOID "O" RING SEAL
 317  1-2 SHIFT VALVE SPRING
 318  1-2 SHIFT VALVE
 320  TORQUE SIGNAL REGUL ATOR VALVE SPRING
 321  TORQUE SIGNAL REGUL ATOR VALVE
 322  PRESSURE CONTROL SOLENOID ASSEMBLY
 323  LINE PRESSURE RELIEF VALVE SPRING
 324  LINE PRESSURE RELIEF VALVE
 325  LINE PRESSURE RELIEF VALVE SPRING RETAINER
 326  TCC REGULATOR APPLY VALVE SPRING
 327  TCC REGULATOR APPLY VALVE
 328  TCC REGULATOR APPLY VALVE BORE PLUG "O" RING SEAL
 329  TCC REGULATOR APPLY VALVE BORE PLUG
 334  TCC PWM SOLENOID ASSEMBLY
 335  TCC CONTROL VALVE
 336  TCC CONTROL VALVE SPRING