P2D66Battery Charging System Negative Contactor C Control Circuit Range/Performance
- Generic OBD-II code · Powertrain
- How the car detects it
- P2D66 flags a coil circuit of minus charging contactor C that is connected but responds outside its expected band while showing neither a break nor a short. P2D66 is not described by any manufacturer, and GM's public tables list no range test for charge contactor coils. A GM patent shows why such a check needs care: the coil current of the same contactor differs markedly between -40, 25 and 85 °C, so the patent compares readings with a reference stored offline for each contactor. CARB requires output parts that a maker monitors on a hybrid to respond properly to commands. Corroded terminals and an aged coil fit this pattern. P2D65 is the open, P2D67/P2D68 low and high, P2D5F the plus side.
- What you may notice
- Charging via contactor C drops out now and then
- Fault occurs mainly in very cold or very hot conditions
- Code returns after clearing
- Likely causes
- LikelyCorroded or loose terminals raising circuit resistance
- PossibleCoil resistance drifted through ageing or overheating
- RareModule software with an unsuitable reference or calibration
- Repair
- Workshop only · Usually a job for a workshop.Typical cost: €100 – €1,500
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.