P07A9: Clutch four has different stuck-on tests in two hybrid modes

P07A9 is the friction-element-D stuck-on code, associated with C4 in this GM hybrid strategy. Unlike a single-threshold description, the table supplies separate failure combinations for mode one and mode two.

Operating mode changes the comparison

The mode-one branch uses C4 slip at or below 30rpm and a strongly negative slip-acceleration criterion, with excess torque above 700Nm. The mode-two branch allows slip up to 80rpm, uses a different acceleration limit and requires excess torque above 180Nm. Both rely on the common input-speed/profile-error prerequisite.

Consequently, a slip value cannot be evaluated correctly without its mode and torque context. The listed overall decision intervals also differ between the two branches.

Do not silently repair the source arithmetic

The mode-one preliminary torque interval is printed as 0.125 seconds beside a count expression that multiplies to 0.25 seconds. This unresolved discrepancy is why that detail is not presented as a reliable service-test timer here.

The separate pass condition requires C4 slip above 75rpm for 0.25 seconds in specified operating states. Preserve the exact range and monitor status when assessing it. The document does not establish a mechanical seizure or prescribe a forced clutch-release test. Further diagnosis requires the correct hybrid-transmission procedure and a qualified technician able to manage propulsion and high-voltage hazards.

Do not combine the two mode-specific branches into one threshold.

Source and applicability

GM 2010 10OBDG10 Hybrid Diagnostics, only the cited controller and monitor. These are historical calibration examples; individual vehicle, engine and hardware applicability is not established. GM PDF, page 162. GM PDF, page 163.