P2D43

Code

Generic P — Powertrain

A/C Compressor Motor Voltage B High

Brand: Generic

Type: P — Powertrain

Views: UK: 24 EN: 35 RU: 30

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Short to battery voltage on compressor motor circuit B (wiring chafing, pin pushed into B+).
Failed compressor motor (electric compressor) or internal short.
Faulty motor driver/module or PCM/ECU output transistor for circuit B.
Poor or corroded ground connections related to the compressor power/driver.
Blown or failed fuse/relay supplying compressor motor circuit B.
High system charging voltage (overcharging alternator) causing elevated circuit voltage readings.

Malfunction Indicator Lamp (MIL) or A/C related warning on dash.
A/C compressor may not engage or may operate incorrectly.
Reduced or no cabin cooling when system commands compressor on.
Stored or repeating DTC P2D43 (may appear with related compressor circuit codes).
Possible fuse or relay failure related to the A/C circuit.

Retrieve freeze frame and freeze data with a scan tool; note battery voltage and engine running voltage when fault set.
Visually inspect wiring harness, connectors and pins at the compressor, motor driver/module, and PCM for damage, corrosion, melted insulation, or water intrusion.
Check related fuse(s) and relay(s) for the A/C compressor power/driver circuit B; inspect for blown fuse or heat damage.
Measure system battery/charging voltage at the battery with engine off and running; note any over-voltage (>15 V).
Backprobe the compressor motor circuit B at the connector and measure DC voltage with key ON (engine off) and engine running; compare to expected ranges.
Measure resistance of the compressor motor windings (with power disconnected) and compare to specifications; look for low resistance indicating internal short.

Typical battery/rest voltage: ~12.4–12.8 V (engine off).
Typical charging voltage: ~13.5–14.8 V (engine running).
Expected compressor drive voltage: near 0 V when off, variable 0–battery voltage when commanded (PWM).
High-voltage threshold (indicative): readings consistently above normal charging voltage range (>15 V) or near battery positive with output expected low.
Motor winding resistance: manufacturer-specific; typical small electric motors show a few ohms to tens of ohms — very low or near 0 Ω suggests short, very high or open indicates open circuit.

Read and record live data and freeze-frame information. Note battery voltage when DTC set. Check for other stored DTCs.
Visually inspect connectors, pins, and harness routing to the A/C compressor and motor driver. Repair any damage.
With battery connected, backprobe compressor motor circuit B at the connector. Measure DC voltage with ignition ON (engine off) and with engine running while commanding A/C on/off using a scan tool. Compare to expected behavior (should be low when off, variable when commanded).
If voltage is abnormally high with command off, disconnect the compressor connector and measure voltage at the harness side to determine if short is upstream.
Measure motor winding resistance with power disconnected. Very low resistance may indicate internal shorted windings; very high or open indicates broken winding.
Inspect and test the motor driver or PCM output for circuit B. Use an oscilloscope to verify PWM switching and that output is not stuck at high voltage.
Check charging system for over-voltage condition (test alternator/regulator); if system voltage is excessive, repair charging system first.
Repair any damaged wiring, corroded connectors, or faulty grounds. Replace defective compressor motor or motor driver/module if confirmed by tests.
After repairs, clear codes and perform A/C system functional test and monitor live data to confirm normal operation and that code does not return.

Wiring short to B+ at connector or harness near compressor.
Defective compressor motor with internal short or insulation breakdown.
Faulty motor driver or PCM transistor for compressor circuit B.
Intermittent connector damage (water intrusion, corrosion) raising sensed voltage.
Charging system overvoltage raising all 12V circuits above thresholds.