P07A3: A clutch that should release can be detected by unexpectedly low slip

P07A3 concerns friction element A, identified as C1 in this GM hybrid monitor. It detects a clutch that remains coupled when the operating state expects otherwise. That is the opposite diagnostic direction from a commanded-on clutch that slips excessively.

Low slip is suspicious only in the specified state

The failing C1 combination includes slip at or below 80rpm, slip acceleration at or below 30rpm/s and mode 2 operation. Excess C1 torque must exceed 320Nm for the stated preliminary interval. The common stuck-clutch enable also requires input speed to differ from its profile by more than 200rpm.

GM lists a 4.5-second failure decision for this combination. Low slip in a normal engaged state cannot simply be substituted for that complete operating context.

Release evidence has its own definition

The following page describes a passing C1 slip speed above 45rpm in specified ranges, sustained for 0.375 seconds. Because failure and pass conditions involve different operating contexts, their numerical overlap should not be treated as an editorial error or a universal clutch-clearance test.

Keep range state, C1 slip, slip acceleration and torque information together. The monitor does not prove that friction material welded or identify a hydraulic cause. A qualified hybrid-transmission technician needs the actual service procedure to investigate coupling behavior safely; deliberately forcing mode changes is not a test method supplied by this table.

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.