Limited Vehicle Speed on the CT6 PLUG-IN

Vehicle speed may be limited on some 2016-2018 CT6 PLUG-IN models (RPO HP9) equipped with the 2.0L 4-cylinder engine (RPO LTG) and automatic-hybrid electric transmission (RPO MRD). DTC P0747 (Transmission Clutch 3 Stuck On) also may be set in the Hybrid Powertrain Control Module (HPCM).

The limited speed condition may be the result of the 1-3 clutch return spring ring (Fig. 15, #1) moving out of its groove, causing the variable 1-4 and 1-3 clutch piston return spring plate to contact the variable clutch plate assembly. (Fig. 15, #2)


Fig. 15


The transmission does not require replacement for this condition. A snap ring retainer is available that will stop the 1-3 clutch return spring ring from rotating, which will keep it securely in its designed groove. The C3 clutch assembly must be disassembled and the clutch pack and spring ring must be replaced along with adding the new snap ring retainer.

During assembly of the C3 clutch assembly, position the 1-3 clutch return spring ring as shown to aid in retainer installation. (Fig. 16)


Fig. 16


Refer to Bulletin #19-NA-128 for additional information and part numbers.


– Thanks to Lane Rezek

Service Procedures and Labor Times Updated
Diagnosing DTC P3075

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