P2160: Near-zero transfer-case speed is judged against an expected-motion state

P2160 is generically a vehicle-speed sensor B low-circuit code. The cited GM implementation evaluates the transfer-case output speed signal against operating conditions that indicate motion should be present. The monitored channel must be identified from this vehicle-specific architecture before choosing a sensor.

A low reading needs a valid expectation of rotation

The published failure boundary is raw transfer-case speed below 25 rpm for more than 4.5 seconds, with a 25-millisecond update rate. Gear state, torque, accelerator position, other speed information and range-change timing contribute to the enable logic.

The table contains multiple enable blocks, including extreme calibration values, without a clear general-purpose road-test interpretation. Those values are not combined here into invented driving instructions. The relevant active block and its calibration must be established for the exact system.

Distinguish absence of activity from a sudden drop

The neighboring P2161 strategy describes a rapid loss of transfer-case speed. It explicitly notes that the same drop can start both monitors' timers, creating a race to which code completes first. One code appearing before the other therefore does not necessarily identify two unrelated physical faults.

Preserve the raw speed history, transmission output speed, range state and timing around the event. A current zero reading without that context is insufficient. The source does not isolate a wiring defect or sensor failure, and safe mechanical or electrical testing requires the applicable transfer-case service procedure.

Source and applicability

2025 GM 06C documented monitor only. Vehicle, engine and controller calibration applicability must be established separately; no model fitment is inferred from the file. GM PDF, physical page 358; GM PDF, physical page 359; GM PDF, physical page 360.