Lost Communication With Generator Control Module
What does U0175 mean?
The U0175 code means the vehicle's onboard diagnostic system has detected: Lost Communication With Generator Control Module. This is a moderate severity code.
Common Symptoms
- Battery warning light illuminated
- Charging system not functioning properly
- Battery draining while driving
- Electrical accessories dimming
- Vehicle may stall due to low voltage
Probable Causes (Ranked by Likelihood)
- Failed alternator with integrated control module Very High
- Damaged wiring between ECM and alternator High
- Corroded alternator connector Moderate
- ECM unable to communicate with smart alternator Low
Step-by-Step Diagnostic Procedure
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Test charging voltage at the battery with engine running (should be 13.5-14.5V)
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Check the alternator connector for corrosion or damage
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Inspect the wiring from the ECM to the alternator
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Verify the drive belt tension and condition
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Use a scan tool to check alternator duty cycle and target voltage
Frequently Asked Questions
Can I drive with code U0175?
Only short distances. Without proper charging the battery will eventually drain and the vehicle will stall. Go directly to a repair shop.
What causes U0175?
Modern vehicles use smart alternators controlled by the ECM. The most common cause is a failed alternator with a built-in control module.
Is U0175 expensive to fix?
Expect $300 to $800. Smart alternator replacement is the most common repair. Wiring fixes are less expensive when applicable.