P2802: Internal transmission range sensor B has a low PWM-circuit signal

P2802 identifies a short-to-ground signature in internal transmission range sensor B's PWM circuit in the reviewed GM ECM table. This is an electrical-range diagnosis, not a direct statement that the transmission has selected the wrong gear.

Signal encoding changes how low is recognized

The displayed sensor type uses voltage directly proportional to the reported signal. Its listed low duty-cycle condition is below 10%. The table also mentions an inverse-proportional alternative, which must not be mixed with the selected direct-proportional configuration.

The controller's ground-short design specification is less than 0.5 ohm between signal and controller ground. That figure describes detection; it does not provide a safe resistance-test procedure for an energized range-sensor circuit.

Battery and duration are part of the decision

Battery voltage must exceed 9 V for more than one second. The diagnostic requires failure time greater than 0.50 second within a sample interval greater than one second.

A brief transition or a value captured before the voltage qualification is met does not reproduce the full monitored condition. Likewise, a displayed range label may conceal the raw PWM behavior that the controller actually evaluates.

Verification should establish the correct sensor encoding, valid raw signal and completion of the enabled circuit test. P2802 does not identify a mechanical shift-linkage fault or prove which component caused the low signal. The source documents Type A, one-trip behavior without prescribing sensor or controller replacement.

Source and applicability

Confirm the vehicle, transmission variant and relevant module before applying this monitor description. GM diagnostic table, PDF page 666.