P2803: Range sensor B signal is high from a power short or an open path

P2803 is the internal transmission range sensor B circuit-high diagnosis in the reviewed GM ECM monitor. The source explicitly allows either a short to power or an open circuit to produce this code, so high does not uniquely identify an unwanted battery connection.

Two electrical signatures share the result

The controller design specifications are less than 0.5 ohm to the voltage source for a power short, or more than 200 kilohms to controller ground for an open path. These characterize the controller's detection capability, not a live resistance-testing instruction.

The selected sensor type is directly proportional, with a listed PWM duty-cycle condition above 92%. The row also describes an inverse-proportional alternative. The actual encoding must be identified before interpreting a duty-cycle measurement.

Timing prevents a one-snapshot diagnosis

Battery voltage must be above 9 V for more than one second. Failure must last more than 0.50 second within a sample interval longer than one second. A later normal reading may not reproduce an intermittent open, while an isolated high transition does not establish the complete decision.

Use the appropriate circuit procedure to separate the two possible fault signatures and retain the raw signal alongside the displayed range state. A gear indication alone does not show which electrical path failed.

Verification should confirm a valid encoded sensor signal and a completed monitor without recurrence. The source lists Type A, one-trip behavior, without establishing mechanical gear engagement or a mandatory range-sensor replacement.

Source and applicability

Confirm the vehicle, transmission variant and relevant module before applying this monitor description. GM diagnostic table, PDF page 667.