2015-2017 Buick Enclave Fuse Box: Solving Electrical Issues and Tow Package Mismatches

Known Issues for 2015-2017 Enclave Fuse Centers

Water Intrusion and Corrosion

One of the most common causes of failure for the Enclave's fuse box is water intrusion. Leaks from a degraded windshield cowl seal or hood seal can allow water to drip directly onto the fuse box cover and seep inside. This moisture leads to corrosion on the internal circuit board and the connector pins, appearing as a green or white powder. The resulting short circuits can cause a wide range of bizarre and intermittent electrical problems.

Internal Relay and Terminal Failure

Many critical relays, such as the one for the fuel pump, are soldered directly to the fuse box's internal circuit board. Over time, these relays can fail, leading to issues like a crank-no-start condition. Additionally, a class-action lawsuit was filed concerning the fuse block terminals losing tension over time, particularly the engine relay terminal. This looseness, worsened by normal engine vibration, can disrupt the electrical connection and cause stalling, loss of power, or a failure to start.

Symptoms of a Failing Fuse and Relay Center

A faulty fuse box can manifest in numerous ways, often making it difficult to diagnose. Because it controls so many different systems, symptoms can seem random and unrelated.

• Crank but No Start: This is a classic symptom of a failed internal fuel pump relay. The engine turns over but won't fire because it's not receiving fuel.
• Multiple, Unrelated Electrical Failures: Systems like the radio, power windows, door locks, and climate control may stop working simultaneously or intermittently.
• Warning Lights on Dash: You may see Stabilitrak, ABS, or other warning lights appear, sometimes accompanied by a loss of power steering or brakes as the vehicle stalls.
• Flickering Lights or Erratic Behavior: Headlights or interior lights may flicker, and components may work one moment and not the next.
• Audible Clicking: A rapid clicking sound may be heard from the fuse box area or door switches as relays attempt to engage but fail due to poor connections.
• Blown Fuses: While a single blown fuse is normal, if the same fuse blows repeatedly, it could indicate a short within the fuse box itself.

OBD-II codes will often point to the component that lost power (e.g., P0119 for engine coolant temp sensor, P1682 for ignition switch circuit) rather than the fuse box itself, which can be misleading for technicians.

Buying a Used 2015-2017 Enclave Fuse Center

A used OEM fuse box is an excellent, cost-effective repair option because it does not require any dealer programming. However, careful inspection is key to getting a good part.

1. Verify Tow Package Compatibility: This is the most important step. You must match the part to your vehicle's configuration. If your Enclave has the factory tow package (RPO code V92), you need a fuse box from a donor vehicle that also had it. The part numbers are different.
2. Check Part Numbers: Match one of the known OEM part numbers (20757040, 23436803, 23436804, 23436805, 23436806, 23436809) to the part you are buying.
3. Inspect for Corrosion: Carefully examine all the external connector pins where the wiring harnesses plug in. Look for any signs of green or white crusty residue. Do not buy a unit that shows any evidence of water damage.
4. Examine the Housing: Check the plastic case for any cracks, melting, or signs of excessive heat, especially around the larger relay sockets.
5. Choose OEM Over Aftermarket: A used original GM part is often more reliable than a new aftermarket unit. Aftermarket versions can use lower-quality internal components that may not last as long. Since no programming is needed, a tested, warrantied used OEM part provides the best value.

Replacement Overview

Replacing the underhood fuse box is a straightforward job that a DIY mechanic can typically complete in about an hour.

1. Disconnect the Battery: Always disconnect the negative battery terminal before working on any major electrical components.
2. Remove the Cover: Unclip and remove the fuse box cover.
3. Unplug Connectors: The large wiring harness connectors have locking levers. Pivot these levers to release the connectors and pull them straight out.
4. Unbolt the Fuse Box: Remove the bolts or nuts securing the fuse box to its bracket in the engine bay.
5. Swap the Unit: Install the replacement fuse box and secure it.
6. Reconnect Everything: Plug in all the wiring harness connectors, ensuring the locking levers click firmly into place. Reconnect the battery terminal.

Cost Comparison

Frequently Asked Questions (FAQ)