With the GM 5L40-E transmission a common mode of failure stems from the malfunction of the torque converter lock up clutch solenoid



which allows the LUC to wear away its lining until metal-to-metal contact produces large amounts of metallic debris in the fluid







This debris then causes further problems in the valve block. It’s essential therefore to check if the fluid has metallic debris in it before replacing any solenoids otherwise the fix will only be temporary.

Phil