U3024 indicates a fault in the communication between the power‑train control module and the ignition input circuit B during the engine start sequence. The PCM detected that the voltage level on this circuit does not match the expected pattern when the ignition is turned on.
A broken wire, corroded connector, or poor ground can prevent the required voltage from reaching the PCM during start.
The switch may not supply the proper 12 V to the PCM when turned to the ON position, causing the correlation error.
A failing battery, loose battery terminal, or defective main power relay can cause voltage drops that trigger the code.
The internal transistor or driver that monitors Ignition Input B may have failed, though this is less common than wiring problems.
Aftermarket alarms, remote starters, or other accessories that tap the ignition circuit can introduce voltage spikes or drops.
No. In the vast majority of cases the code is caused by wiring, connectors, or the ignition switch. Replacing the PCM without confirming a hardware fault is usually unnecessary and costly.
A weak or poorly connected battery can cause low voltage on the ignition input circuit, which may trigger U3024. Ensure the battery and its terminals are in good condition before pursuing other repairs.
If the engine starts and runs normally, the vehicle can be driven, but intermittent start or stall issues may occur. It is advisable to diagnose and repair the fault promptly to avoid being stranded.
Yes. Any accessory that taps the ignition circuit can affect the voltage seen by the PCM. Disconnecting or rewiring the accessory often resolves the code.