2017 Subaru Legacy & Outback Keyless Access Module: Programming, Problems, and Replacement

Symptoms of a Failing Vehicle Access Control Module

When the access control module begins to fail in a 2017 Subaru Legacy or Outback, the symptoms are often sudden and can be mistaken for a dead key fob battery. It's common for owners to replace the fob battery only to find the problems persist.

• Key Fob Unresponsive: The most common symptom is the complete failure of the key fob. The buttons will not lock or unlock the doors, and the vehicle will not detect the key for keyless entry or push-button start.
• Car Starts and Immediately Stalls: You may be able to get in the car using the mechanical key, but when you press the start button, the engine cranks, runs for about two seconds, and then shuts off. This is accompanied by a flashing security indicator light on the dashboard, signaling an immobilizer fault.
• Intermittent Operation: Before complete failure, the system may work intermittently. You might need to be very close to the vehicle for it to work, or it may function one moment and not the next.
• No Communication with Scan Tool: A professional scan tool may be unable to communicate with the keyless access module, pointing to an internal failure or a communication line issue.

Associated Diagnostic Trouble Codes (DTCs)

A professional scan tool that can read Body (B) and Communication (U) codes is necessary to diagnose this module. Common codes pointing to a faulty module or related circuit issue include:

• B1571 - Reference Code Incompatibility: Indicates a mismatch in the security codes between the access module and the Engine Control Module (ECM). This code will always appear after installing a new or used module, before it has been programmed.
• B1572 - IMM Circuit Failure: Signals a communication breakdown between the access module and the ECM. While this can indicate a failed module, it can also be caused by corroded or loose engine-to-chassis ground wires, which should be inspected first.
• B1575 - Incorrect Immobilizer Key: This code is stored when the module does not recognize the key being used to start the car.
• B1577 - IMM Control Module EEPROM: This code points directly to an internal memory or processing failure within the Vehicle Access Control Module itself, strongly suggesting the module needs to be replaced.

Known Issues and TSBs

While no specific recalls target this module for the 2017 model year, there are common issues and related service bulletins for the keyless access system.

• Water Intrusion: The module is located in the right rear quarter panel, an area that can sometimes be susceptible to moisture from a leaking window seal or body seam. On similar Subaru models, water damage is a known cause of failure for modules in this location. Always inspect a failed module for signs of corrosion or water entry.
• Faulty Ground Wires: As noted with DTC B1572, poor ground connections between the engine and the chassis can interrupt communication within the immobilizer system, mimicking the symptoms of a failed module. A Subaru technical service bulletin for a related issue highlights the importance of checking these grounds as a diagnostic step.

Buying a Used Vehicle Access Control Module

Given the high cost of a new module, a used OEM unit is an excellent, cost-effective alternative. However, there are critical factors to consider to ensure a successful repair.

1. Verify the Part Number: The original part number for the 2017 Legacy and Outback is 88801AL190. This has been superseded by part number 88801AL191. Either number is compatible. Do not install a module with a different part number, even if it looks identical.
2. Physical Inspection: When your used part arrives, inspect it carefully. Look for any signs of corrosion on the pins of the electrical connector. Check the plastic case for cracks or evidence of being opened. Any sign of water damage is a major red flag.
3. Budget for Programming: A used module is not plug-and-play. The cost of professional programming is a mandatory part of the repair. Before buying the part, get quotes from local automotive locksmiths and the Subaru dealer so you know the total cost.
4. Why Used OEM is a Good Choice: Unlike some mechanical parts, electronic modules like this do not wear with mileage in the same way. A used OEM module from a reputable recycler is functionally identical to a new one, but costs significantly less. As long as it is programmed correctly, it will perform just like a new part.

Replacement and Programming Guide

Location

The Vehicle Access Control Module is located in the rear of the vehicle, behind the interior trim of the right-hand (passenger side) quarter panel. In an Outback, this is inside the cargo area. In a Legacy, it is behind the trim panel next to the rear seat.

Replacement Steps (DIY Feasible)

Physically swapping the module is straightforward for a DIYer with basic tools. The main challenge is carefully removing the interior trim panels without breaking any clips.

1. Disconnect the Battery: Disconnect the negative terminal of the 12V battery before starting any electrical work.
2. Remove Cargo Area/Quarter Panel Trim: This is the most time-consuming step. You will need to remove the cargo floor, foam trays, and various plastic trim pieces on the passenger side to gain access. This typically involves removing cargo tie-down hooks and popping out plastic clips with a trim removal tool.
3. Locate and Unbolt the Module: The module is a small black box bolted to the vehicle's inner body structure. It is held in place by one or two 10mm bolts.
4. Disconnect and Swap: Unplug the single electrical connector from the old module, remove the bolts, and swap in the replacement unit.
5. Reassemble: Re-install the new module, connect the wiring, and partially reinstall the trim. Do not fully reassemble until programming is confirmed to be successful. Reconnect the battery.

Programming Procedure (Professional Required)

After the new or used module is installed, the vehicle is immobilized and will not start. It must be towed or visited by a mobile technician for programming.

1. A technician connects a specialized scan tool (like the Subaru Select Monitor or an advanced locksmith tool) to the OBD-II port.
2. The technician's tool communicates with the car's main computers and registers the unique ID of the replacement access control module, synchronizing it with the ECM and BIU.
3. Once the module is registered to the car, all key fobs must be re-registered to the new module. The technician will perform a key registration procedure, which erases all old keys and adds your existing keys to the new module's memory.
4. After programming is complete, the technician will test all key fob functions (lock, unlock, push-button start) to confirm the repair was successful.

Cost Comparison

The total cost of this repair varies dramatically depending on whether you use new or used parts and who you choose for programming.

Frequently Asked Questions (FAQ)