Coolant Bypass Valve A Control Circuit High

Where it lives

For P0E77, the description names the valve as the part involved.

Check these first

• A short to voltage on the coolant bypass valve A control circuit
• A failed valve A actuator holding the line high
• An open ground at valve A
• Water in the valve A connector

What to do next

1. Check the valve A control wire for a short to voltage
2. Inspect the valve A connector for water and corrosion
3. Verify the valve A actuator ground
4. Command valve A with a scan tool and watch the signal
5. Replace the bypass valve A actuator if the line stays high
6. Clear the code and retest

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