P0689 on 2013-2017 GMC Acadia: Causes and Fixes for Stalling

What's Unique About the 2013-2017 Gmc ACADIA

On this generation of the GMC Acadia and its platform mates (Chevy Traverse, Buick Enclave), the Underhood Bussed Electrical Center (UBEC), or fuse box, is a known weak point. As documented in GM Technical Service Bulletins #PIT5643 and #19-NA-276, the connection at terminal 51 of the X3 connector is prone to 'poor terminal tension' which leads to micro-arcing and corrosion. This single, specific failure point interrupts power to the ECM and is the most common reason for a P0689 code on these vehicles, often causing sudden stalling or a no-start condition.

Diagnostic Flowchart

Tap your situation to follow the diagnostic path that matches what you're seeing on this vehicle.

Generation note: The 2013-2017 year range primarily covers the first-generation Acadia (2007-2017). In 2017, GM sold both the first-generation model as the 'Acadia Limited' and the new, smaller second-generation model. The issues described here, particularly the TSBs, apply to the first-generation platform, including the Acadia Limited.

Symptoms You May Notice

• Engine stalls while driving, often intermittently
• Reduced Engine Power message on the dash
• Engine cranks but will not start
• Check Engine Light is on
• Traction Control or StabiliTrak warning lights may appear

Most Likely Causes

1. Corrosion/Arcing at UBEC Connector X3, Terminal 51 🔴 High Probability As identified in GM TSBs #PIT5643 and #19-NA-276, this specific terminal, which supplies power to the ECM, suffers from poor terminal tension. This loose connection causes electrical arcing, which creates heat, corrosion, and increased resistance, leading to a voltage drop.
   How to confirm: Disconnect the battery. Unbolt and lift the underhood fuse box (UBEC). Unplug the X3 connector (often black or gray) and visually inspect pin 51 and its corresponding terminal. The damage can be a very subtle black or brown spot from arcing, so close inspection is key. TSB #PIT5643 suggests using a cell phone camera to zoom in on the terminal to see the arc spot. 🎬 Watch this video to see the exact connector inspection process. The YouTube channel 'Sparky's Answers' has a detailed video showing this exact inspection on a 2014 Acadia.
   Typical fix: If arcing is confirmed, GM's recommendation is to replace both the UBEC and the female terminal in the harness connector using a terminated lead (pigtail). The terminal is replaced by de-pinning it from the connector and splicing in the new lead. If no arcing is visible but the terminal feels loose, replacing only the terminal lead may be attempted first.
   Est. part cost: $15-$50 for a terminal lead, $250-$400 for a new UBEC.
2. Faulty Powertrain/ECM Power Relay 🟡 Medium Probability Relays are mechanical switches that can wear out over time. The contacts can become pitted or the internal coil can fail, causing intermittent or complete failure to supply power.
   How to confirm: Locate the powertrain or ECM relay in the underhood fuse box. Swap it with an identical relay from a non-critical circuit (like the horn or rear defogger). If the problem resolves, the relay is bad. This is a good first step before inspecting the UBEC.
   Typical fix: Replace the faulty relay.
   Est. part cost: $10-$30
3. Internal UBEC (Fuse Box) Failure ⚪ Low Probability Beyond the external connectors, the internal circuits or bus bars within the multi-layered fuse box can crack or corrode, often due to heat expansion and contraction, causing a voltage drop. This can happen even if the external pin 51 looks clean.
   How to confirm: This is a diagnosis of exclusion. If the X3 connector is clean, the relay is good, and wiring is intact, but voltage tests at the ECM fuse sockets still show a drop, the UBEC itself is the likely culprit.
   Typical fix: Replacement of the Underhood Bussed Electrical Center (UBEC).
   Est. part cost: $250-$400

Rare But Worth Checking

• Poor Battery Terminal Connection or Ground: While less common for this specific code, a corroded or loose main battery terminal or a faulty engine/chassis ground can cause widespread low voltage issues that could potentially trigger a P0689 code. Always check the basics first. Some owners have noted that the factory ground points can be painted over, causing intermittent connections.
• Faulty Engine Control Module (ECM): → Shop Engine Control Module (ECM) It is extremely rare for the ECM to be the cause. It should only be considered after all other possibilities, especially the UBEC and its wiring, have been thoroughly ruled out as per the TSBs.

Diagnosis Steps

1. Scan for codes. Confirm P0689 is present, and note if P1682 is also stored, as is highly likely.
2. Check battery voltage and ensure terminals are clean and tight.
3. As a simple first step, swap the ECM/Powertrain relay with a known good, identical relay from the same fuse box and see if the problem is resolved.
4. If the problem persists, proceed with the TSB inspection. Disconnect the negative battery terminal.
5. Unbolt and carefully lift the UBEC to access the connectors underneath. There are several plastic tabs holding it in place.
6. Identify and disconnect the X3 connector. It is a large, multi-pin connector.
7. Thoroughly inspect terminal 51 and the corresponding male pin on the UBEC for any signs of corrosion, melting, or tiny black/brown marks from arcing. Use a magnifying glass or your phone's camera to zoom in for a better view.
8. If arcing damage is found on the UBEC pin, the most reliable repair is to replace both the UBEC and the wire terminal lead in the X3 connector.
9. If no damage is visible, check for poor pin tension on terminal 51. If the terminal feels loose compared to its neighbors, it should be replaced.
10. If all wiring and power supplies from the UBEC are confirmed good, the ECM itself may be faulty, though this is highly unlikely.

Parts You'll Likely Need

• Underhood Fuse Box (UBEC) (OEM #Varies by VIN, e.g., 23235703 for some models) 🎬 See a step-by-step walkthrough of the fuse box replacement. — This is the most common failure point. The male pin for terminal 51 becomes damaged by arcing. TSBs recommend replacement if arcing is found. Part number is specific to year and options, must verify with VIN.
  Trusted brands: ACDelco (OEM)
  OEM price range: $300-$400
  Aftermarket price range: $250-$350
• Terminated Wire Lead (OEM #84757974) — This part is required to replace the damaged female terminal in the X3 connector. It is a wire with the correct terminal pre-crimped. This part number replaces older numbers 19301751 and 19301767.
  Trusted brands: ACDelco (OEM)
  OEM price range: $15-$50
  Aftermarket price range: $10-$30
• Powertrain/ECM Relay — A simple and inexpensive part to rule out first. A failing relay can cause the low voltage condition.
  Trusted brands: ACDelco, Bosch
  OEM price range: $20-$40
  Aftermarket price range: $10-$30

Related Codes That Often Appear With This One

• P1682 — P1682 (Ignition 1 Switch Circuit 2) is almost always seen with P0689 on these vehicles. The ECM compares two different ignition voltage inputs; when the power supply from the UBEC (related to P0689) is faulty, it creates a discrepancy with the other ignition signal, triggering P1682. The TSBs and owner complaints consistently link these two codes as a pair.
🎬 Watch a mobile mechanic diagnose and repair these specific codes.

Technical Service Bulletins (TSBs) & Recalls

• PIT5643: Preliminary Information bulletin that first identified the cause as 'arcing/corrosion on terminal 51 of the X3 connector at the UBEC' due to loose terminal tension.
• 19-NA-276: A formal service bulletin that provides the official repair procedure to correct reduced engine power or stalling with DTCs P1682 and/or P0689 by inspecting and replacing the terminal lead for cavity 51.

Platform-Specific Known Issues

• NHTSA Technical Service Bulletin #PIT5643 specifically calls out diagnosing DTCs P0689 and/or P1682 by inspecting for arcing/corrosion on terminal 51 of the X3 connector at the UBEC.
• NHTSA Technical Service Bulletin #19NA276 supersedes the preliminary information, providing a formal repair procedure for the 'poor terminal tension on terminal 51' that causes stalling and these codes.
• A real-world owner complaint filed with the NHTSA (ODI #11589389) for a 2014 GMC Acadia documents the vehicle stalling and throwing codes P0689 and P1682, directly referencing TSB #PIT5643 and the YouTube channel 'Sparky's Answers' which details the repair.

Mechanic-Grade Diagnostic Values

• ECM/PCM Power Relay Sense Circuit Voltage — expected: 12.0 - 13.5 V with key in 'ON' position. Failure: Voltage lower than 12.0V or dropping intermittently.
• ECM/PCM Power Relay Coil Resistance — expected: 70 - 120 Ω. Failure: Resistance is outside of this range.
• Wiring continuity from relay output to ECM sense pin — expected: Less than 0.1 Ω. Failure: Resistance higher than 0.1 Ω indicates corrosion or a damaged wire.
• Voltage difference between Ignition 1 and Ignition 2 circuits (triggers P1682) — expected: Less than 3V. Failure: A difference greater than 3V for more than 1 second.

Scan Tool Commands That Help

• GDS2 (GM Techline Connect): Powertrain Relay ON/OFF Command — Use this output control function to command the powertrain relay on and off multiple times while listening for an audible or tactile click from the relay. This helps verify if the ECM can control the relay and if the relay itself is mechanically functioning.

Wiring & Ground Locations

• X3 Connector, Pin 51 — Underneath the Underhood Bussed Electrical Center (UBEC), also known as the fuse box.. This is the specific pin and connector identified in GM TSBs #PIT5643 and #19-NA-276 as the primary failure point. It supplies ignition voltage to the ECM, and poor terminal tension here leads to arcing, corrosion, and a voltage drop that sets P0689 and P1682.
• G110 — Right front of the engine, mounted to the cylinder head.. This is a primary engine ground. A poor connection here can cause various electrical issues, including unstable voltage references for the ECM.
• G112 — Rear of the engine, mounted to the rear of the cylinder head.. This is another critical engine ground point. Ensuring it is clean and tight is a fundamental step in diagnosing any ECM-related electrical fault.
• G114 — Left rear of the engine.. This ground serves multiple components. While not a direct ECM ground, poor integrity can introduce electrical noise and instability into the system.

Real Owner Repair Stories

• YouTube channel 'Sparky's Answers' (2014 GMC Acadia) — Intermittent stalling, Check Engine Light with codes P0689 and P1682.
  ❌ Tried (didn't work) The video begins after the initial diagnosis, directly referencing the GM TSBs as the starting point.
  ✅ What actually fixed it The technician inspected the underside of the UBEC and found a very subtle, dark arc mark on the male pin for terminal 51. The repair involved replacing the entire UBEC (fuse box) and the corresponding female wire terminal in the X3 connector harness. This completely resolved the stalling.
• YouTube channel 'C&J's Mobile Automotive LLC' (2007 GMC Envoy (similar GM platform issue)) — Stalling when warm, followed by a no-start condition. Codes P1682 and P0689 were present.
  ❌ Tried (didn't work) Initial checks showed weak power coming from the fuse box, but the external connectors appeared fine.
  ✅ What actually fixed it The technician drilled out the plastic rivets and disassembled the UBEC itself. An internal copper trace/bus bar was found to be cracked. Soldering the cracked trace restored continuity and fixed the problem without replacing the entire fuse box.

OEM Part Supersession History

• 19301751, 19301767 → 84757974 — Part number consolidation and potential design/material improvements for the terminated wire lead used to repair the X3 connector.
  Heads up: The new part number (84757974) is the correct service part. The older numbers may no longer be available. Note that these are often sold in packs of 5, but only one is needed for the repair.

Model Year Variations Within This Range

• 2017: In 2017, GM produced two different Acadias. The first-generation platform (2007-2016) was continued and sold as the 'Acadia Limited'. A new, smaller, redesigned second-generation Acadia was also introduced. The P0689/P1682 UBEC issue is specific to the first-generation platform, which includes the 2017 Acadia Limited. The all-new 2017 Acadia has a different electrical architecture.