Engine Control Module (ECM) Power Relay/Switch Circuit/Performance
ECM relay circuit issue detected.
Heads up: this code wasn't in our hand-written library yet, so DiagCoach AI built this page on the fly. Double-check critical specs against service info before condemning parts.
What it means (plain English)
The computer that controls the engine isn't getting the right power because there's a problem with the relay that turns it on or off.
What the computer is actually seeing
The Engine Control Module (ECM) expects to see a certain voltage level for the power relay; if it's below 9 volts when turned on, it'll trigger this code.
What a healthy reading looks like
ECM power relay should receive 12-14 volts; voltage drop should be less than 0.5 volts across connections when energized.
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 the battery voltage. Ensure it's between 12-14 volts. If not, charge or replace the battery.
- 22. Inspect the fuses associated with the ECM power relay. Replace any blown fuses detected.
- 33. Locate the ECM power relay. Check for any visible damage or burnt marks.
- 44. Measure the voltage at the relay while the ignition is ON. It should be 12-14 volts. If not, check wiring and connectors for corrosion or damage.
- 55. If the relay is functioning but the ECM isn’t receiving power, inspect the circuit from the relay to the ECM for continuity and any potential shorts or opens.
Common causes
- Bad ECM power relay
- Corroded wiring or connectors
- Blown fuse in the relay circuit
- Faulty ECM
Typical repair cost
$$$
Related codes
Frequently asked questions
Is it safe to drive with this code?
It's not recommended, as it can lead to engine stalling or failure to start.
Will the problem come back after repair?
If proper repairs are made to the relay and wiring, it should not return.
Why does this code often pair with P0680?
P0680 also points to ECM relay issues, indicating common electrical problems in the power circuit.
Working a real vehicle right now?
Let DiagCoach walk you through it live with your specific symptoms, vehicle, and what you've already checked.
Start guided diagnostic →