Loose, corroded, or damaged battery terminal connections or ground straps at the affected module.; A failing or weak battery that drops voltage excessively during cranking or under load.; Chafed, pinched, or intermittently shorted power wire between the battery/fuse box and the module.; A faulty ignition switch or power relay that opens intermittently under vibration or heat.; Corrosion or water intrusion at the module connector pins, causing high resistance or intermittent contact.; A failing module internal power supply or voltage regulator that drops out under certain conditions.; A blown or partially failed fuse, or a fuse box with loose terminals, causing intermittent power loss.

DTC codes / U35xx · Network communication / U3507

U3507Control Module Input Power B Circuit Intermittent/Erratic

Q: What does code U3507 mean?

Control Module Input Power B Circuit Intermittent/Erratic. U3507 is a generic network code indicating that a control module has detected an intermittent or erratic fault on the power circuit feeding its own internal input power, typically the voltage supply that keeps its memory and logic alive. The module logs this code when the voltage on that circuit momentarily drops, spikes, or cuts out in a way that is not consistent with normal operation, often during cranking, rough road input, or a loose connection.

U3507 is a generic network code indicating that a control module has detected an intermittent or erratic fault on the power circuit feeding its own internal input power, typically the voltage supply that keeps its memory and logic alive. The module logs this code when the voltage on that circuit momentarily drops, spikes, or cuts out in a way that is not consistent with normal operation, often during cranking, rough road input, or a loose connection.

SystemNetwork

Code typeGeneric (all makes)

SeverityMedium

Fix difficultyIntermediate

AreaNetwork communication

Symptoms you may notice

Illumination of the malfunction indicator lamp (MIL) or a message on the driver information center.
Intermittent no-start or crank-no-start condition, especially after the vehicle sits or over bumps.
Random electrical glitches such as flickering interior lights, radio resets, or false warnings from other modules.
Loss of communication with one or more modules during a scan tool session.
Often no symptoms besides the warning light, with the fault only appearing as a stored code.
Accessory functions (windows, seats, climate) that work intermittently or reset unexpectedly.

Common causes, most likely first

Loose, corroded, or damaged battery terminal connections or ground straps at the affected module.
A failing or weak battery that drops voltage excessively during cranking or under load.
Chafed, pinched, or intermittently shorted power wire between the battery/fuse box and the module.
A faulty ignition switch or power relay that opens intermittently under vibration or heat.
Corrosion or water intrusion at the module connector pins, causing high resistance or intermittent contact.
A failing module internal power supply or voltage regulator that drops out under certain conditions.
A blown or partially failed fuse, or a fuse box with loose terminals, causing intermittent power loss.

How to diagnose and fix it

Perform a battery load test and check charging system voltage to rule out a weak battery or alternator.
Inspect and clean battery terminals, ground straps, and the module's ground connection for corrosion or looseness.
Use a scan tool to monitor live data for the affected module's input power voltage while wiggling harnesses and connectors.
Check the fuse and relay feeding the module, and swap the relay with a known-good identical unit to test for intermittent operation.
Perform a voltage drop test on the power circuit from the battery to the module while loading the circuit to reveal high resistance.
Inspect the harness for chafing, pinched wires, or water intrusion at connectors, repairing as needed.
If all external circuits test good, substitute a known-good module or perform a bench test to confirm internal fault before replacement.

Intermittent power faults that fool technicians

A battery that passes a simple voltage check can still have a failing internal cell that drops voltage only under cranking load, setting this code without any other symptom.
The module that stores U3507 is often not the module with the fault; the code can be set by a module that shares a power feed with the one that is actually dropping out.
Corrosion inside a connector that looks clean from the outside is a common cause, especially on vehicles with leaks or in humid climates, and only a pin drag test or voltage drop test reveals it.
Aftermarket accessories tapped into the power circuit can introduce intermittent loads or poor connections that trigger this code, so always check for non-factory wiring.
A loose ground can cause the module to see erratic voltage on its power input even when the positive side is perfect, so never overlook ground quality.

Can I keep driving with U3507?

The vehicle is generally safe to drive if it starts and runs normally, but avoid long trips or heavy electrical loads until the fault is repaired, because an intermittent power loss can cause a no-start or unexpected module shutdown. If the engine stalls or multiple warning lights appear, stop driving and have the vehicle towed for diagnosis.

Tools that help

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Guidance is general and written for all OBD-II vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.