Ford P1250: Alternator Load Input Low
The P1250 code indicates that the Powertrain Control Module (PCM) has detected an alternator load input signal that is below the expected threshold or outside the normal operating range. This Ford-specific code relates to the alternator load monitoring circuit, which allows the PCM to assess the electrical system's demand and regulate alternator output via the voltage regulator. The 'low' signal suggests the PCM is not receiving proper feedback on the current electrical load, preventing optimal charging system regulation.
01. Most Common Causes
- Faulty alternator or integrated voltage regulator
- Damaged wiring or poor connection in the alternator load signal circuit
- Excessive resistance at the alternator or PCM connector
- Internal PCM failure in the load detection circuit
- Weak or undercharged battery affecting system reference
02. Symptoms You Will Notice
- Battery warning light illuminated
- Dimming headlights or electrical issues
- Possible difficulty starting or dead battery
03. Step-by-Step Diagnosis
Check battery voltage and condition; charge or replace if weak.
Inspect alternator wiring and connectors for damage, corrosion, or looseness.
Test alternator output and voltage regulator function.
Check for excessive resistance in the load signal circuit between alternator and PCM.
If all else is good, consider PCM internal fault and reprogram or replace.
1. Frequently Asked Questions
Is it safe to drive?▼
You can drive short distances, but the battery may discharge, leading to a stall or no-start. It's best to diagnose and repair promptly.
How much does it cost to fix?▼
Typically $150–$400 for alternator replacement; wiring repairs $100–$200; PCM replacement $500–$1000.