Code Definition

P085C — Transmission shift module communication signal high - Circuit B

System: Powertrain  |  Type: Generic (OBD-II Standard)  |  Make: Generic

About P085C

P085C is a generic (obd-ii standard) powertrain diagnostic trouble code. It belongs to the P-prefix family of codes, which covers engine, transmission, emissions, or fuel-system faults.

When P085C is stored, the module has detected a signal or supply voltage higher than the expected operating range.

Scanning & clearing: A generic OBD-II scan tool will usually read and clear powertrain (P) codes. For live data, freeze-frame capture, and bi-directional tests you may need a more capable scan tool that supports the vehicle's ECM protocol.

Because P085C is a generic OBD-II code, its base definition is shared across manufacturers. The specific diagnostic steps, reference values, and repair procedures can vary by vehicle, and the TaT Diagnostic Assistant includes verified procedures submitted by working technicians.

Code Information

The P085C fault code is set when the Engine Control Module (ECM) or Transmission Control Module (TCM) detects a high communication signal from the transmission shift module in Circuit B. The transmission shift module is critical for controlling the gear selection and shift operations within the transmission system. A high communication signal typically indicates an electrical issue such as a short to power in the module's communication circuit.

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