U0140 on 2021-2024 Chrysler Pacifica: Lost BCM Communication Causes and Fixes

What's Unique About the 2021-2024 Chrysler PACIFICA

For the 2021-2024 Pacifica, this code is notably linked to specific, documented issues. A Technical Service Bulletin (TSB 08-170-24) directly connects U0140 to inoperable power sliding doors, a hallmark feature of the minivan. The fix identified in the bulletin is a software update for the Power Sliding Door Module (PSDM), indicating that on this platform, the problem is often a correctable software glitch rather than a mandatory hardware failure. Additionally, these vehicles are equipped with a Security Gateway Module (SGM) that can prevent full diagnostic functions with aftermarket scan tools, sometimes requiring a specific bypass cable 🎬 Watch: How to connect your scan tool using a 12+8 adapter. or a dealer-level tool (wiTECH) to properly diagnose network issues.

Diagnostic Flowchart

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

Symptoms You May Notice

• Check Engine Light (Malfunction Indicator Lamp or MIL) is on.
• Left and/or right power sliding doors are inoperable.
• Malfunctioning power windows or door locks.
• Erratic or non-functional interior or exterior lights.
• Wipers behaving irregularly.
• Multiple warning lights on the dashboard (e.g., ABS, traction control).
• Key fob remote may stop working.
• Vehicle may not start in some cases.

Most Likely Causes

1. Power Sliding Door Module (PSDM) Software Glitch 🔴 High Probability A specific TSB (08-170-24) was issued for 2021-2024 Pacificas (built on or before August 18, 2024) with power sliding doors (Sales Code JRK), indicating a known 🎬 Watch: Troubleshooting tips for Chrysler Pacifica power sliding door issues. software issue from the manufacturer that directly causes code U0140.
   How to confirm: A dealer or qualified shop using a wiTECH scan tool can check if the vehicle's VIN and build date fall under TSB 08-170-24 and if the PSDM software is outdated.
   Typical fix: Update the Power Sliding Door Module (PSDM) with the latest software. This is a 0.2-hour labor operation under warranty.
   Est. part cost: $0
2. Low Battery Voltage or Poor Ground 🟡 Medium Probability → Shop Vehicle Battery Control modules are sensitive to voltage. These vans use both a main and an auxiliary battery; a failure in either can cause widespread electrical issues. A weak battery or a corroded ground can cause intermittent communication failures across the vehicle network.
   How to confirm: Test the battery voltage (should be ~12.4V+ engine off, and ~13.5-14.5V engine on). Inspect the main battery ground and BCM ground connection for tightness and corrosion. The BCM is located under the dash to the left of the steering column. A ground voltage drop test at the BCM should show ≤100–200 mV.
   Typical fix: Recharge or replace the faulty battery (main or aux). Clean or repair the ground connection.
   Est. part cost: $0-$400
3. Wiring Harness or Connector Issue 🟡 Medium Probability Complex wiring in areas like the sliding doors and under the dash can be prone to chafing or loose pins. Communication codes are often traced back to a single point of failure in the CAN bus wiring.
   How to confirm: Visually inspect the wiring harnesses and connectors going to the BCM for damage, corrosion, or looseness. A multimeter can be used to check for continuity and shorts on the CAN bus wires. With the battery disconnected, resistance between CAN High (Pin 6) and CAN Low (Pin 14) at the OBD-II port should be approximately 60 ohms.
   Typical fix: Repair the damaged section of the wiring harness or clean/re-pin the affected connector.
   Est. part cost: $5-$50
4. Faulty Body Control Module (BCM) ⚪ Low Probability → Shop Body Control Module While less common than software or wiring faults, the BCM itself can fail internally due to moisture intrusion or electronic component failure.
   How to confirm: This is typically a diagnosis of exclusion. If all software is up to date, and all power, ground, and network wiring to the BCM test good, the module itself is the likely culprit. A dealer-level scan tool may also show the BCM as completely unresponsive.
   Typical fix: Replace the Body Control Module and program it to the vehicle using a tool like wiTECH.
   Est. part cost: $300-$600

Rare But Worth Checking

• Interference from Aftermarket Accessories: Poorly installed remote starters, alarms, or audio equipment that tap into the vehicle's CAN bus can disrupt network communication and trigger a U0140 code.
• Faulty Gateway Module (SGM): The Security Gateway Module, located behind the climate control panel, facilitates communication. While not a common failure point, a fault within this module could theoretically disrupt BCM communication.

Diagnosis Steps

1. Check for Technical Service Bulletins (TSBs). Specifically, see if TSB 08-170-24 (for sliding doors) or TSB 08-033-22 (for other BCM software updates) applies to your vehicle.
2. Perform a full vehicle scan with a capable scan tool. Note if other modules also report communication loss codes. Access may be limited by the Security Gateway Module (SGM), requiring a bypass cable for non-dealer tools.
3. Check the battery and charging system. Ensure stable voltage is above 12.4 volts with the engine off and typically 13.5-14.5V when running. Remember to check both main and auxiliary batteries.
4. Inspect all fuses related to the BCM and other body control systems. The main fuse box is in the engine bay on the driver's side.
5. Visually inspect the wiring and connectors at the Body Control Module (located under the dash, left of the steering column) for any signs of damage, moisture, or corrosion.
6. If TSB 08-170-24 is applicable, have a dealer perform the PSDM software update. A battery charger must be used to maintain stable voltage (13.2-13.5V) during the flash.
7. If software is not the issue, perform network tests. With the battery disconnected, check resistance between CAN-C pins (6 and 14) at the OBD-II port. A reading of ~60 ohms is expected. Check for continuity and shorts to power/ground on the CAN bus wires at the BCM connector.
8. If all wiring, power, grounds, and software are confirmed to be good, suspect a faulty BCM.

Parts You'll Likely Need

• Body Control Module (BCM) (OEM #68593675AA (Note: Multiple part numbers exist, and they are frequently superseded. Always verify with VIN.)) — This is the module that has lost communication. It is replaced only after software, wiring, and power/ground issues have been ruled out. Part number 68360198AC from pass 1 has been superseded multiple times. Other examples include 68585830AB and 68415281AC, but fitment varies greatly.
  Trusted brands: Mopar
  OEM price range: $260-$450
  Aftermarket price range: $250-$450

Technical Service Bulletins (TSBs) & Recalls

• 08-170-24: Addresses MIL illumination with DTC U0140-00 and inoperable power sliding doors on 2021-2024 models, fixed by a PSDM software update.
• 9100221: A general bulletin that mentions U0140 and advises following published diagnostic information to check module connections.
• 08-033-22: For 2022 Pacifica/Voyager, this TSB involves a BCM software update to fix various electrical concerns, including key fob detection and liftgate operation, which can be related to BCM communication health.

Platform-Specific Known Issues

• TSB 08-170-24 explicitly links code U0140 to inoperable power sliding doors on 2021-2024 Pacificas, with the prescribed fix being a software update to the Power Sliding Door Module (PSDM).
• TSB 9100221 (from pass 1) is a general diagnostic note advising technicians to follow standard procedures to ensure all module connections are secure, reinforcing that connection integrity is a key checkpoint.
• TSB 08-033-22 (for 2022 models) involves a BCM software update to address issues like false 'key fob not detected' warnings and other electrical anomalies, which can be related to BCM communication health.
• The dual-battery system (main and auxiliary) is a known source of complex electrical problems. A failing auxiliary battery can drain the main battery and cause low-voltage conditions that trigger communication codes like U0140.

Mechanic-Grade Diagnostic Values

• CAN Bus Resistance (Key Off) — expected: ~60 Ω (±5 Ω) across CAN-H (Pin 6) and CAN-L (Pin 14) at the OBD-II port.. Failure: A reading of ~120 Ω indicates a lost terminating resistor or an open in the bus. A reading near 0 Ω indicates a short between CAN-H and CAN-L.
• CAN Bus Voltage (Key On, Engine Off) — expected: CAN-High (Pin 6 to Ground): ~2.5V to 3.0V. CAN-Low (Pin 14 to Ground): ~2.0V to 2.5V.. Failure: Voltages stuck high, low, or at 0V point to a short to power, short to ground, or an open circuit.
• BCM Ground Voltage Drop (Under Load) — expected: ≤100–200 mV. Failure: Higher voltage indicates a poor ground connection, which can cause the module to drop offline intermittently.

Hidden / Shadow Codes Worth Checking

• U0140-00: The '-00' is a Failure Type Byte (FTB) indicating a generic 'No Subtype Information' or 'Lost Communication' event. This is the most common subtype and confirms the BCM has stopped sending expected messages. (see via A professional scan tool like wiTECH or a high-end aftermarket scanner will display the full DTC with its failure type byte.)

Scan Tool Commands That Help

• wiTECH 2.0: Restore Vehicle Configuration — This function is required after replacing a BCM to program it to the vehicle's specific configuration. It is also used in several TSBs after a software flash to ensure all modules are correctly aligned with the vehicle's equipment.
• wiTECH 2.0: Proxy Configuration Alignment — After replacing any module on the CAN bus (including the BCM or even the radio), a proxy alignment is critical. It synchronizes all modules, ensuring they recognize each other on the network. Failure to perform this can cause communication codes like U0140.
• wiTECH 2.0: Reprogram BCM — Used to apply software updates as prescribed by Technical Service Bulletins (TSBs) to fix known software glitches that can cause U0140 or other electrical issues.

Wiring & Ground Locations

• Security Gateway Module (SGM) — Located behind the climate control and shifter knob panel. The panel must be pried off to access the module, which is held by three screws.. This module controls diagnostic access. To perform deep diagnostics or programming on the BCM with an aftermarket tool, a 12+8 bypass cable must be connected directly to the SGM's connectors.
• G300 — At the base of the left 'B' pillar.. This is a major body ground point. Corrosion or looseness here can affect multiple systems controlled by the BCM, leading to communication errors.
• G301 — At the base of the right 'B' pillar.. Similar to G300, this is another critical body ground point. Verifying its integrity is a key step in diagnosing network faults.
• BCM Connectors — The BCM itself is located under the dashboard, to the left of the steering column. It has multiple large connectors (often designated C1, C2, C3, etc.).. These are the direct interface for the BCM. All power, ground, and CAN bus signals must pass through these connectors. Checking for pin tension, corrosion, or damage here is essential.

Real Owner Repair Stories

• YouTube Commenter (Chrysler Pacifica (year not specified, but applies to models with power sliding doors)) — Warning message "Sliding door power unavailable, operate manually".
  ❌ Tried (didn't work) Initial attempts to use the power door buttons failed.
  ✅ What actually fixed it A system reset procedure. First, ensure the gas cap door is firmly closed. Then, manually open the malfunctioning sliding door all the way until it latches. Finally, manually close the door completely until it latches. This process may need to be repeated up to three times to recalibrate the door module, which can resolve software glitches, often after a battery disconnect or low voltage event.
• Reddit user r/ChryslerPacifica (2021 Chrysler Pacifica) — Driver side sliding door starts to open, then stops, with a dash message "Sliding door path blocked; check fuel door."
  ❌ Tried (didn't work) Visually checking the door tracks for obstructions.
  ✅ What actually fixed it The problem was identified as an issue with the fuel door interlock mechanism. This safety feature has a cable that prevents the sliding door from opening when the fuel door is open. A fault in this cable or its sensor can falsely report that the fuel door is open, blocking door operation and potentially contributing to communication errors with the door modules.