U3023: Control Module Input Power Circuit A - Ignition Input On/Start Circuit Correlation

What it means

Control Module Input Power Circuit A - Ignition Input On/Start Circuit Correlation: the value does not correlate with the related sensor or expected pattern.

At a glance

• Usually lights the warning light of the system that lost communication

How it works

Input power circuit A supplies a control module through an ignition ON/START path. The module compares that supply or its reported state with the related ignition input and sets U3023 when the two do not correlate as expected. A mismatch can interrupt module operation or its communication with other systems.

Common causes

Most likely first.

1. Wiring or relay fault between supply and ignition path
2. Gateway module routing CAN messages incorrectly
3. CAN terminating resistor (120 Ω) drifted out of spec

Symptoms

• Multiple warning lights may illuminate
• Affected modules may go into limp mode or shut down
• Specific functions inoperative depending on module
• Diagnostic tools may show communication faults

How to diagnose it

1. Save freeze-frame data and scan for related power-supply, ignition-input, and communication faults to see when circuit A lost correlation.
2. Compare circuit A power and the module's ignition ON/START state in live data while switching the ignition on and starting the vehicle.
3. Inspect circuit A wiring, fuses, relay connections, and grounds for looseness, corrosion, heat damage, or a poor connection.
4. Test the circuit A relay and supply path during the ON and START states, checking for interruptions against the manufacturer's specification.
5. If supply and ignition inputs agree at the module, check gateway reporting and CAN network termination against the manufacturer's specification.

Common fixes

• Clean and secure circuit A power, ground, or relay connections.
• Repair damaged wiring or a poor splice in the ignition ON/START supply path.
• Replace a relay or fuse connection only if testing confirms it is failing under the required ignition state.
• Correct a confirmed gateway reporting or CAN network fault if circuit A supply and input signals are sound.

Can I keep driving?

The module may lose power during ignition transitions, causing dependent functions or communication to drop out. If this affects a safety-related system or the vehicle stalls or behaves unpredictably, stop driving and arrange inspection.