Code
P1AE800
BYD
P — Powertrain
DC charging positive contactor return-check error
AI status
Completed
Completed
100%
Causes
- Open or short in contactor feedback (return) wiring or connectors
- Contactor coil or internal position sensor failed
- Contactor mechanically welded or stuck (contacts not moving)
- Faulty contactor driver or control module (BCU/charger)
- Poor connector corrosion, water ingress, or loose terminals in HV/DC charge circuit
- Blown fuse or damaged relay in control/feedback circuit
Symptoms
- DC (fast) charging prevented or stops immediately when initiated
- Charge session reports contactor/charger fault or safety stop
- Vehicle cannot enable HV charging circuit for DC input
- HV accessory or charging relay amp draw abnormal; possible clicking/humming at contactor
- Possible protective derating of HV system or unable to accept DC power
What to check
- Read and record freeze-frame and live data from BCU/charger; note when code sets and any related codes
- Visual inspection of positive contactor, connectors, and wiring for corrosion, damage, overheating, or water ingress
- Check harness routing for chafing, pinched wires, or signs of mechanical damage
- Inspect fuses, contactor driver relay(s) and associated HV interlocks
- Attempt DC charge while monitoring status bits and feedback signal in live data
- With vehicle safe and HV disabled per manufacturer procedure, measure resistance of contactor coil (compare to spec)
Signal parameters
- Contactor command: digital/driver output from BCU/charger — expected to switch from 0 V (off) to control voltage (refer to manufacturer spec) when energizing
- Feedback/return signal: open/closed indicator to BCU — when contactor is closed the feedback should show continuity (near 0 Ω or a low voltage drop depending on topology); when open it should indicate open circuit or defined high level
- Typical coil resistance: manufacturer-specific; measure coil ohms with HV discharged and compare to service spec
- Expected response time: feedback should change state within specified milliseconds after command (refer to service manual)
- Watch for intermittent or noisy waveform on feedback line with oscilloscope if available (glitches, bouncing, or floating levels indicate wiring or sensor issues)
Diagnostic algorithm
- Gather info: record all related DTCs and freeze-frame data. Confirm code repeats and note conditions (ignition state, charging attempt).
- Visual: inspect positive contactor assembly, connector seals, and wiring for physical damage, corrosion, or overheating. Repair obvious issues.
- Connector and pin check: with HV system disabled and locked out, disconnect contactor harness. Inspect pins for corrosion, bent pins, or pushed-out terminals. Clean and repair as needed.
- Continuity and resistance: measure continuity of feedback circuit from contactor connector to BCU/charger and measure contactor coil resistance. Compare to manufacturer spec. Replace contactor if coil open or shorted or resistance out of spec.
- Driver output: with proper safety procedures and test equipment, command contactor ON while monitoring driver output from BCU/charger and the contactor feedback signal. Verify driver provides expected voltage/current and feedback toggles correctly.
- Wiggle and stress test: while commanding ON, gently manipulate wiring and connectors to reproduce intermittent faults.
- Insulation and short checks: check for unintended shorts between feedback, coil, HV+, and chassis ground.
- Module check: if wiring and contactor test good, check BCU/charger driver functions and related control relays/fuses. Consider swapping/bench-testing the driver if possible or updating module software if a known fault exists.
- Replace and verify: replace faulty contactor or repair wiring as required. Clear codes, attempt DC charge and verify code does not return and that feedback timings and voltages are within spec.
- Post-repair validation: perform multiple charge cycles and road/charge tests to confirm reliability and absence of intermittent returns.
Likely causes
- Damaged/loose connector at the positive contactor
- Broken/shorted feedback wire between contactor and BCU/charger
- Failed contactor (coil, internal sensor, or welded contacts)
- Faulty contactor driver output from BCU or charger module
Fault status
Status
DC charging positive contactor return-check error — feedback signal inconsistent with commanded contactor state; charging inhibited until fault is resolved.
Repair difficulty: Medium
Diagnostic time: 0.5-2.5 hours
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