Power Supply Circuit Voltage Low
The engine control module (ECM) detected low voltage in the power supply circuit.
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What it means (plain English)
The computer in your vehicle isn't getting enough power. Instead of the usual 12-14 volts, it's dropping below 10 volts.
What the computer is actually seeing
The ECM monitors the battery voltage and expects a range between 12-14 volts. When it sees a voltage drop to 9 volts or lower, it throws this code.
What a healthy reading looks like
The expected voltage at the battery should be 12.4-14.7 volts with the engine running.
Guided diagnostic — the DiagCoach way
Don't just throw parts at it. Walk through these in order — each step tells you whether to keep going or stop and fix what you found.
- 11. Check battery voltage using a multimeter. Ensure it's between 12.4-14.7 volts.
- 22. Examine battery connections for corrosion or looseness. Clean and tighten as needed.
- 33. Inspect the power supply wiring for any visible damage or wear.
- 44. Verify ground connections to the ECM. Clean and secure all grounds if they're loose or corroded.
- 55. If all wiring and connections are good, test the ECM power supply inputs. Expected values should be within the standard operating range.
- 66. If voltage is still low, consider replacing the battery or further diagnosing the charging system.
Common causes
- Weak battery
- Poor battery connections
- Faulty power supply wiring
- Bad ground connections
- Faulty ECM
- Short circuit in the power supply circuit
Typical repair cost
$100-$600
Related codes
Frequently asked questions
Is it safe to drive with this code?
It's best to avoid driving until this is fixed, as low voltage can lead to other electrical issues.
Will this code come back after clearing it?
If the underlying issue isn't resolved, the code is likely to return.
Why does this code show up with SPN 1769?
Both codes relate to electrical supply issues, often stemming from a faulty battery or poor connections.
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