P2D57Generator B Control Circuit Range/Performance
- Generic OBD-II code · Powertrain
- How the car detects it
- P2D57 belongs to a second alternator, called generator B, as fitted to some heavy trucks; GM, for instance, offered a secondary generator (option KHB) on 2019 Silverado medium-duty trucks with the 6.6 L diesel. The code concerns the control channel of that machine: the engine computer's command and the regulator's response do not fit together, or the signal leaves its plausible band. No manufacturer documents P2D57 publicly. Infineon's LIN regulator chip TLE8881-3 shows what such a regulator reports: an electrical error flag for a field terminal shorted to ground or battery, an open field winding or excessive battery voltage, debounced over 250 or 1,000 ms; if communication stops, it falls back to a default set point. Generator A uses P065B. The charge lamp may light.
- What you may notice
- Charge warning lamp or message
- Second alternator charges at a fixed default voltage or not at all
- Likely causes
- LikelyDamaged control line (LIN or command wire) or corroded connector
- PossibleFaulty voltage regulator of the second alternator
- RareReplacement alternator with an incompatible regulator
- Repair
- Medium · Usually a job for a workshop.Typical cost: €50 – €700
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.