ECM/PCM Power Input Signal Range/Performance
The P2506 code indicates that the Engine Control Module (ECM) or Powertrain Control Module (PCM) has detected a voltage or signal from its power input that is outside the expected range or not performing correctly. This can be caused by a failing alternator, battery issues, poor electrical connections, or a faulty ECM/PCM itself. The module monitors its own power supply voltage and sets this code when it sees an anomaly, which can lead to erratic vehicle behavior or no-start conditions.
01. Most Common Causes
- Faulty alternator not charging properly
- Weak or dead battery
- Corroded or loose battery terminals or ground connections
- Faulty ECM/PCM power relay or fuse
- Internal ECM/PCM failure
02. Symptoms You Will Notice
- Check Engine Light illuminated
- Engine stalling or difficulty starting
- Erratic transmission shifting or reduced power
- Electrical accessories malfunctioning (lights dimming, radio issues)
03. Step-by-Step Diagnosis
Step 1: Scan for additional codes and record freeze frame data.
Step 2: Inspect battery voltage at rest (should be ~12.6V) and while running (should be 13.5-14.5V).
Step 3: Check all battery cables, ground straps, and ECM/PCM power and ground connections for corrosion or looseness.
Step 4: Test the alternator output and charging system voltage regulator.
Step 5: If all else is good, suspect internal ECM/PCM failure and consider reprogramming or replacement.
04. Commonly Affected Makes
05. Frequently Asked Questions
Is it safe to drive with this code?▼
It is not recommended to drive with this code as it can cause stalling, loss of power, or complete electrical failure, leading to unsafe driving conditions.
How much does it cost to fix?▼
The cost to diagnose and repair P2506 typically ranges from $50 to $150 for diagnosis, plus parts and labor. If the ECM/PCM needs replacement, costs can exceed $500.