P0742 on Chevrolet: How to Diagnose & Fix

Both the 8-speed and 10-speed automatic transmissions can develop a shudder during light acceleration. This torque converter clutch issue is widespread across GM trucks. Multiple TSBs have been issued addressing this concern.

The 8L45 8-speed automatic transmission can develop a shudder during light acceleration, typically between 25-50 mph. This is caused by torque converter clutch issues, similar to problems in other GM vehicles with this transmission family.

Transmission shuddering is common in Equinox models, typically caused by torque converter clutch issues or depleted transmission fluid additives. The shudder is most noticeable during light acceleration between 25-50 mph.

The 2017-2022 Malibu with the 2.0T (LTG) engine uses a GM 9-speed automatic that can exhibit shudder, harsh shifts, and delayed engagement. The 9-speed is sensitive to fluid condition and requires proper DEXRON HP fluid. GM has released multiple TCM calibration updates. The 1.5T Malibu does not use this transmission (6-speed automatic through 2018, CVT from 2019).

The C7 Corvette with the 7-speed manual or 8-speed automatic (the 8L90 automatic arrived for 2015; 2014 automatics used the 6L80 six-speed) can develop an annoying driveline vibration/shudder at low speeds, particularly during gentle acceleration from a stop. The 7-speed manual uses a dual-mass flywheel that can develop chatter. The 8-speed automatic (8L90) shares the torque converter shudder issue with GM trucks. The transaxle-mounted differential and half-shafts can also contribute to vibrations.

The Lumina's automatic transaxle is a 4T60-E on 1995-1996 cars. GM began phasing in the 4T65-E from 1997, and the 4T60-E is listed for the Lumina through 2000, so a 1997-2000 car could have either unit. Check the transmission ID tag before buying parts or a used unit. Owners on CarComplaints report slipping, surging on the 1-2 and 2-3 shifts, failure to shift into overdrive (top speed limited to about 30-45 mph), dropping into neutral at highway speed, and complete loss of drive. Owners say dealers pointed to a failed pump, a failed control valve, solenoids, or a sticking valve. One owner reported a shattered gear casing that left only 1st gear. On the 4T65-E, Sonnax says wear at the 3-4 accumulator piston pin or bore causes 3-4 shift problems: harsh 4th, no 4th, or a burned 4th clutch. Starting with mid-2000 models, all 4T65-E units got an upgraded valve body. Reported failures range from about 42,000 miles to about 130,000 miles.

The 4T65-E automatic transmission used in the 2000-2011 Impala is one of the most failure-prone GM transmissions. Common failures include the 1-2 accumulator piston cracking (causing harsh 1-2 shift), pressure control solenoid failure (erratic shifts and slipping), and the forward clutch hub cracking (complete loss of forward gears). The 3.8L supercharged models are especially hard on the 4T65-E due to higher torque output. Many 4T65-E transmissions fail between 80,000-120,000 miles.

Express 2500 and 3500 vans built through roughly 2009 use the 4L80E. It is a genuinely strong unit, but the torque converter lockup clutch is its recognized failure point on high-mileage commercial vans. As the TCC lining wears, the transmission raises line pressure to compensate, so the first thing an owner notices is not slipping but hard, banging shifts - a symptom that gets misread as a valve body or solenoid problem. Shudder at lockup speeds, a bucking sensation around 45-55 mph and eventually a stall-on-stop follow. Related, heat and vibration kill the 2-3 shift solenoid, and GM bulletins for these vans document harsh shifts, a delayed 2-3 shift and slipping in third with solenoid replacement as the remedy. A separate quirk owners report on Express vans specifically is transmission fluid pushing out of the vent tube when the unit gets hot and the fluid expands, which then reads as a leak. Realistic service life is 120,000-180,000 miles; converters on 200,000-plus mile vans should be assumed suspect.