P0717: How to Diagnose & Fix — Input/Turbine Speed Sensor Circuit No Signal

The 722.9 7G-Tronic transmission conductor plate (internal electrical board with speed sensors) fails, causing limp mode, harsh shifting, and loss of gears. The electrical connector corrodes or the sensors crack from heat cycling.

First-generation Enclaves (2008-2017) use the 6T70/6T75 6-speed automatic, whose stamped-steel 35R wave plate can crack at the teeth after enough shift cycles. When it fractures, the transmission abruptly loses 3rd, 5th, and reverse gears, and debris can damage the valve body, drums, and torque converter. Failure typically occurs in higher-mileage 2008-2012 builds.

The Aztek's 4T65-E four-speed automatic suffers from pressure control (force motor) solenoid failure that drives line pressure to maximum, causing harsh shifting and accelerating internal wear; GM addressed related harsh-shift complaints in TSB 02-07-30-022B (faulty transaxle connectors, 2001-2004) and cold-weather reverse servo seal shrinkage in TSB 04-07-30-028. NHTSA complaints for the 2003 Aztek document gear failure, no-forward-movement, and shifter problems at an average of about 157,000 miles. Left unaddressed, the harsh-shift condition commonly progresses to slipping and loss of 3rd/4th gear requiring a rebuild or replacement.

Equinox models with the GM 6T70/6T75 six-speed automatic suffer shudder, harsh or delayed shifts, slipping, and loss of reverse. A common root cause is failure of the 3-5-reverse wave plate, which can crack and cause extreme shudder when reverse is engaged and eventual loss of drive. Overheated/degraded fluid that loses viscosity accelerates internal wear. Failures typically appear between roughly 60,000 and 150,000 miles. Owners report bucking when engaging gear, failure to shift out of 2nd, and inability to engage reverse.

The 722.6 five-speed automatic (fitted to W202 facelift cars from ~1996 onward and all 2001-2002 W203s) uses an electronic conductor plate mounted on top of the valve body that integrates the speed sensors and routes signals to the solenoids. The plate fails for two reasons: (1) the internal RPM sensors get coated by ferrous wear particles when the fluid is never changed, producing implausible-slip codes, and (2) the soldered traces and embedded capacitor crack from heat cycling. Failure puts the transmission into limp-home mode — stuck in 2nd gear, harsh 1-2 and 2-3 shifts, or no upshift at all. Often accompanied by codes P0717, P0720, P0731-P0736 and a transmission warning light. This is the single most common 722.6 failure across every Mercedes chassis that uses it.