U3506
Control Module Input Power B Circuit High
Input power line B voltage above expected range. A communication loss with this module breaks any function relying on its data — diagnostic tools may show 'no response' and dependent modules can fall into limp mode.
Input power line B voltage above expected range. A communication loss with this module breaks any function relying on its data — diagnostic tools may show 'no response' and dependent modules can fall into limp mode.
Common causes
- high
Alternator regulator failed
One of the most commonly reported causes for this code — check this first.
Typical part cost: $60-660
- low
Gateway module routing CAN messages incorrectly
Less common, but worth ruling out after the more likely causes.
Typical part cost: $60-660
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First things to check
- 1Confirm the code with a scan tool and check for additional related codes.
- 2Inspect the relevant sensors, wiring, and connectors for damage or corrosion.
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Related codes
See related trouble codes
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Frequently asked questions
What does U3506 mean?
U3506 means "Control Module Input Power B Circuit High". It is a generic OBD-II code that points to a fault in the network / communication.
What are the most common causes of U3506?
alternator regulator failed; gateway module routing can messages incorrectly; can terminating resistor (120 ω) drifted out of spec — these are the most commonly reported causes. Verify with a proper diagnosis before replacing parts, or use the Wrenchify app for a vehicle-specific diagnosis.
Can I keep driving with this code?
This code can put the vehicle into limp or reduced-power mode. Avoid extended driving and have the vehicle diagnosed promptly. Use the Wrenchify app for a full diagnosis specific to your vehicle.
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