P2729

P2729 is the open-circuit code for Pressure Control Solenoid G — and the existence of a G solenoid (the seventh in alphabetical labeling) means you're on a transmission with at least 7 hydraulic elements, which in practice means the 10-speed automatics jointly developed by Ford and GM (10R80 / 10L80 / 10L90). The TCM diagnostic logic is identical to P2720: command current to the solenoid, measure actual current, and if commanded is non-zero while measured stays at zero, set an open-circuit fault. Cheapest-first ladder: drop the pan if it's an internal solenoid (which on 10-speeds it is), ohm the PCS-G coil cold (8-30 ohms typical, lean toward the lower end on 10R80/10L80 designs at around 4-8 ohms), and confirm an open vs in-spec reading on a DMM. If the coil reads in spec, the failure is harness/connector/TCM-driver side; back-probe at the lead-frame pass-through for voltage drop (greater than 0.2 V end-to-end is suspect) and at the TCM driver pin with a scope. PCS-G drive current sits at 0.5-1.5 A under PWM at 100-300 Hz like the other PCS units. Caveat: on a 10-speed, accessing PCS-G means dropping the pan and pulling the valve body, which is $400+ in labor before parts; ALWAYS verify the open is at the solenoid coil and not the internal harness before condemning the part, because a $300 solenoid swap doesn't fix a $1,500 lead-frame.

Vehicle-specific patterns: 2017+ Ford 10R80 in F-150, Mustang GT, Bronco, Expedition, and Lincoln Navigator is the primary platform for P2729 — the 10R80 uses seven hydraulic elements with PCS solenoids labeled A through G, and Ford's early-build (2017-2019) production had documented internal-harness issues that produced intermittent open circuits on the G channel before the calibration and lead-frame updates rolled out. 2017+ GM 10L80/10L90 in Silverado, Tahoe, Yukon, Camaro ZL1, and Cadillac Escalade shares about 80% of its architecture with the 10R80 (joint development program) and sees the same P2729 pattern from lead-frame harness corrosion at high mileage. Other 7-element transmissions exist (some Aisin AWR6B45 variants, certain Mercedes 9G-Tronic implementations) but rarely throw P2729 specifically in field service. Estimated repair: $450 to $3,200.