6L80E.TC01

Failures 6L80E/6L90E transmissions with JMBX Converter
Problem: iron on iron in the converter; the friction material has perished on the lockup plate.
This can have several causes, which need to be looked at:
• Failing valves in the pump
• Wrong oil (6L80 Judder)
• Old TCM which needs to be replaced
• Excessive wear of the AFL-valve and/or TCC Regulator Valve
Many people overlook that the damage in the converter can be the result of failures in the pump.
That is why you are advised to always do a thorough Vacuum Test on the pump and the valve body, as instructed in the Sonnax Guide.
Should you detect excessive Vacuum leakage, you need to replace the Pump Body or ask us for repair. Check our 6L80E.PUM05 or contact us for more information.
It is adviced to modify the converter with a forged Cover and a Sonnax Piston to prevent failures in the future.
Cover # Z-GM-CC-13
Piston # Z-GM-DA-17P
Naturally if you have your converter repaired with us, this modification is a standard procedure. Our partner CSR repairs include the Billet cover, HD piston, HD plate and spring retainer.
Be aware that this problem might reoccur, always keep an extra eye on the pump in this case!
More information you can find in this extensive tech advisory by Sonnax.