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DTC codes / U30xx · Network wiring and bus faults / U3005

U3005Retained Accessory Power

U3005 indicates that the body control module (BCM) or a dedicated control module has detected a fault in the retained accessory power (RAP) circuit, which keeps power flowing to accessories like the radio and windows after the ignition is turned off. The computer monitors voltage and current on the RAP relay control circuit and sets this code when the circuit is open, shorted, or the relay does not respond as commanded.

SystemNetwork
Code typeGeneric (all makes)
SeverityMedium
Fix difficultyIntermediate
AreaNetwork wiring and bus faults

Symptoms you may notice

  • Accessories such as the radio, power windows, or cigarette lighter remain powered after the key is removed and the driver door is opened.
  • Accessories do not stay powered after the ignition is turned off, forcing the driver to restart the vehicle to operate them.
  • Battery drains overnight or after sitting for a few hours because the RAP circuit stays energized.
  • Intermittent operation of retained accessories, sometimes working and sometimes not.
  • Often no symptoms besides the warning light, especially if the fault is in the control circuit rather than the relay itself.

Common causes, most likely first

  1. Faulty retained accessory power (RAP) relay, which may be stuck open or closed.
  2. Blown fuse or fusible link in the RAP circuit, often due to a shorted wire or component.
  3. Damaged or corroded wiring in the RAP circuit, including open circuits, shorts to ground, or shorts to voltage.
  4. Failed body control module (BCM) or the module that controls the RAP function, such as a smart junction box.
  5. Ignition switch or push-button start system not sending the correct off signal to the BCM.
  6. Aftermarket accessories improperly wired into the RAP circuit, causing excessive current draw or backfeeding.

How to diagnose and fix it

  1. Verify the battery is fully charged and in good condition, as low voltage can cause false RAP codes.
  2. Check all fuses related to the RAP circuit, including those in the underhood and interior fuse boxes, and replace any that are blown.
  3. Inspect the RAP relay by swapping it with an identical known-good relay from another circuit and clearing the code to see if it returns.
  4. Use a digital multimeter to check for voltage and continuity on the RAP relay control circuit at the BCM and relay socket, looking for opens or shorts.
  5. Test the ignition switch or push-button start operation to ensure it properly signals the BCM when the ignition is turned off.
  6. Disconnect aftermarket accessories one at a time to see if the code disappears, especially if they were recently installed.
  7. If all wiring and components check out, diagnose the BCM with a scan tool capable of bidirectional controls to command the RAP relay on and off and monitor response.

RAP relay failures and hidden wiring faults

  • A stuck RAP relay is one of the most common causes, but it can be intermittent and may not show up unless the circuit is load-tested with a bulb or a scope.
  • The code can be set by a voltage drop on the RAP circuit that is too small to affect accessory operation, so the driver may notice nothing until the battery dies.
  • Aftermarket alarms, remote starters, or stereo installations often tap into the RAP circuit and introduce faults that mimic a failed BCM.
  • Some vehicles use a virtual RAP function inside the BCM without a physical relay, so a wiring diagram is essential before condemning parts.
  • A weak battery or poor ground connection can cause the BCM to misreport RAP circuit status, leading to unnecessary module replacement.

Can I keep driving with U3005?

You can usually drive the vehicle safely, but if the RAP circuit is stuck on, the battery may drain and leave you stranded. Avoid parking for long periods without a charger until the fault is repaired, and do not ignore a battery that keeps going dead.

Tools that help

Tools we recommend are in the Auto Veteran shop on Amazon. As an Amazon Associate we earn from qualifying purchases.

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

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