U0103 on 2017-2024 Chrysler Pacifica: Causes and Fixes for Lost Communication With Gear Shifter

What's Unique About the 2017-2024 Chrysler PACIFICA

The Chrysler Pacifica uses a fully electronic rotary dial shifter, which has no mechanical linkage to the transmission for selecting gears. This design is entirely dependent on the CAN bus network to function. While space-saving and modern, it introduces single points of failure. Any disruption in communication, whether from the shifter module itself, wiring, a central 'star' connector hub, or software, can render the vehicle unable to shift gears. This issue is common enough that many owners report intermittent problems that can sometimes be temporarily resolved by wiggling wires or even hitting the dash near the glove box where a key network connector is located.

Diagnostic Flowchart

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

Symptoms You May Notice

• "Service Shifter" message on the instrument cluster.
• Vehicle will not shift out of Park.
• Shifter dial is binding, difficult to turn, or the indicator lights (PRND) do not illuminate. [S2408000065, 17]
• Transmission is stuck in a single gear (limp mode), often with reduced acceleration.
• Check Engine Light or other transmission warning lights are on.
• Vehicle may not start or may start but not accelerate.
• Multiple other warning lights (FCW, Lane Sense, Park Sense) may illuminate simultaneously due to network-wide communication loss.
• Intermittent issues that temporarily resolve after turning the vehicle off and on, or by wiggling wires behind the glove box.

Most Likely Causes

1. Faulty CAN Bus Star Connector 🔴 High Probability A central CAN bus hub, known as the 'star connector', is located behind the glove box and acts as a junction for many modules. The female pin terminals within the connectors can lose tension over time, causing intermittent open circuits. This is a widely reported failure point.
   How to confirm: A temporary 'fix' by wiggling the connectors or tapping on the dash above the glove box strongly suggests this is the issue. A technician can use an oscilloscope to observe corrupt data packets on the CAN bus network when the fault is active. The star connector itself can be replaced, or the individual wire terminals can be replaced with new ones to restore proper pin tension.
   Typical fix: Replace the star connector block and/or re-pin the associated female connectors with new terminals. Parts are available from electronics suppliers like Mouser or TE Connectivity.
   Est. part cost: $20-$70
2. Faulty Electronic Gear Shift Module (EGSM) 🟡 Medium Probability The internal electronics of the rotary shifter module can fail over time, causing it to stop communicating on the network. This is a known issue addressed by TSB S2408000065.
   How to confirm: After confirming power, ground, and CAN bus wiring to the module are intact, the module itself is the likely culprit. A professional scan tool may show the module as 'offline'.
   Typical fix: Replace the Electronic Gear Shift Module. 🎬 Watch this quick walkthrough on how to remove the shifter knob. The new module may require programming by a dealer or qualified shop.
   Est. part cost: $250-$450
3. Software Glitch Requiring a Module Update 🟡 Medium Probability Chrysler issued TSB 21-027-17 for 2017 Pacificas built before Feb 15, 2017, to address this code by reprogramming the Transmission Control Module (TCM). The update improves shifter interlocking logic and resolves several DTCs, including U0103. A dealer must check for applicability before replacing parts.
   How to confirm: A dealer or a shop with access to Chrysler's wiTECH software can check if the vehicle's TCM software is outdated and if TSB 21-027-17 applies.
   Typical fix: Reprogram the Transmission Control Module (TCM) with the latest software version.
   Est. part cost: $0-$200
4. Wiring Harness or Connector Issue 🟡 Medium Probability Wiring to the center console shifter can be subject to stress, and connectors can become loose or corroded. On older Pacifica models, chafing of the main harness in the driver's side wheel well area was a known problem, though less documented on the 2017+ generation.
   How to confirm: Visually inspect the wiring harness leading to the EGSM. Use a multimeter to check for continuity, shorts, and proper voltage on the power, ground, and CAN bus circuits at the module's connector.
   Typical fix: Repair the damaged section of the wiring harness or clean/replace the faulty connector. Wiring repair kits are available.
   Est. part cost: $10-$100
5. Low Battery Voltage or Poor Ground ⚪ Low Probability Sensitive electronic modules can malfunction when system voltage is low or unstable. Some owners report a parasitic draw related to the shifter or media hub lights staying on, which can drain the battery and trigger a cascade of low-voltage codes.
   How to confirm: Test the battery's state of charge and health. Check that the battery terminals and main chassis ground connections are clean and tight. A technician may need to perform a parasitic draw test to see if a module is failing to go to 'sleep'.
   Typical fix: Charge or replace the battery. Clean and secure all ground connections. Diagnose and repair any underlying parasitic draw.
   Est. part cost: $0-$250

Rare But Worth Checking

• Faulty Transmission Control Module (TCM): While less common than the shifter module itself, the TCM is the other end of the communication line. If it fails, it can't receive messages from the shifter, which can also trigger a U0103 code.
• Faulty Front Control Module (FCM) / Body Control Module (BCM): On related platforms, a faulty FCM (which acts as a network gateway) has been found to cause U0103 by disrupting CAN bus communications.

Diagnosis Steps

1. Check battery voltage and ensure it is above 12.4 volts. Clean battery terminals and check chassis grounds.
2. Use a professional scan tool with a 12+8 adapter cable to bypass the security gateway and check for codes in all vehicle modules.
3. Note all codes present, especially other 'U' (network) codes, which point to a wider bus problem.
4. Attempt to communicate directly with the Electronic Gear Shift Module (EGSM) using the scan tool. If it doesn't respond, it points toward a module, wiring, or star connector issue.
5. As a quick test, tap firmly on the dashboard above the glove box or wiggle the connectors on the star connector block located behind the glove box to see if the fault clears, which indicates a bad connection.
6. Gain access to the EGSM connector behind the center console/dash and the star connector behind the glove box.
7. Visually inspect the wiring harnesses and connectors for any signs of damage, corrosion, or loose pins.
8. Using a multimeter and a wiring diagram, check for proper power and ground at the EGSM connector.
9. Check the CAN bus circuit wires for proper resistance (should be ~60 ohms across the two wires with the battery disconnected) and for shorts to power or ground.
10. For advanced diagnosis, use an oscilloscope to monitor CAN High (Pin 6) and CAN Low (Pin 14) at the OBD-II port to look for corrupted data packets, which often appear as distorted square waves.
🎬 Watch: Diagnosing Pacifica CAN bus communication issues with an oscilloscope.
11. If wiring, power, and ground are all good, and the star connector is confirmed to be functioning, the EGSM is the most likely failed component.
12. Before replacing parts, check with a dealer for any applicable software updates (TSBs) for the TCM or EGSM, especially TSB 21-027-17 for 2017 models.

Parts You'll Likely Need

• Electronic Gear Shift Module (Rotary Shifter)

Related Codes That Often Appear With This One

• P1B13-00 — This code for 'Park by Wire Unintended Out Of Park Position' often appears with U0103, as the system cannot confirm the park command from the non-communicating shifter.
• P1CC9-00 — 'Unable To Engage Gear' is a direct consequence of the lost communication with the gear shift module.
• U11E3 — Another communication code that is often logged alongside U0103, pointing to a broader issue with the Electronic Gear Shift Module. [S2408000065]
• U1267 — This code is also cited in a TSB with U0103, indicating a loss of communication with the EGSM. [S2408000065]

Technical Service Bulletins (TSBs) & Recalls

• S2408000065: Shifter Binding Or "Service Shifter" Message On The Cluster. DTSs U11E3, U0103, U1267 For Loss Of Communication With The Electronic Gear Shift Module
• 21-008-21: Lost Communication With Electric Gear Shift Module
• 21-027-17: Flash: Transmission Shift and Drivability Enhancements (For 2017 models built on/before 02/15/2017)

Platform-Specific Known Issues

• Chrysler issued TSB #21-027-17 for 2017 Pacificas built on or before February 15, 2017, which involves reprogramming the TCM to fix issues that can cause U0103. The update specifically improves shifter interlocking logic.
• TSB #S2408000065, dated in 2024, specifically addresses a 'Service Shifter' message and shifter binding accompanied by code U0103, pointing to a known issue with the Electronic Gear Shift Module. [S2408000065]
• A faulty CAN Bus 'star connector' located behind the glove box is a frequent culprit for this code, causing intermittent communication loss across multiple modules. Owners report that tapping on the dash or wiggling the connector can temporarily restore function.

Mechanic-Grade Diagnostic Values

• CAN Bus Network Resistance — expected: ~60 Ohms (± 3 Ohms) across CAN_H and CAN_L pins (e.g., Pins 6 and 14 at OBD-II port) with battery disconnected.. Failure: A reading of ~120 Ohms indicates a missing terminating resistor or an open in the bus. A reading significantly less than 60 Ohms (e.g., 40 Ohms) suggests an extra terminating resistor or a shorted module.
• CAN Bus Voltage (Key On, Engine Off) — expected: CAN_H: ~2.5V to 3.5V. CAN_L: ~1.5V to 2.5V. Both lines should idle near 2.5V when recessive (not actively communicating).. Failure: Voltages that are stuck high, low, or fluctuating wildly indicate a short to power/ground or a module pulling the bus down. An oscilloscope is required for accurate diagnosis of data packets.
• EGSM Power and Ground — expected: Approximately 12V at the power supply pin with key on. Near 0 Ohms resistance to a known good chassis ground at the ground pin.. Failure: No voltage or low voltage indicates a fuse, relay, or wiring fault. High resistance on the ground circuit indicates a corroded or loose ground connection.

Hidden / Shadow Codes Worth Checking

• U0103-00: This is the standard 'active' DTC indicating a current loss of communication with the gear shift module. (see via Standard professional scan tool.)
• U0103-87: This sub-code for 'Missing Message' is often logged alongside the primary code and specifically points to the EGSM not sending its expected data packets onto the network. (see via Dealer-level scan tool like wiTECH or advanced aftermarket scanners.)

Scan Tool Commands That Help

• wiTECH or equivalent advanced scan tool: Proxy Configuration Alignment (Proxi Alignment) — This procedure is required after replacing the Electronic Gear Shift Module (EGSM), Body Control Module (BCM), or other key network modules. It synchronizes the vehicle's configuration across all modules. Failure to perform a proxi alignment can result in a flashing odometer and persistent communication codes.
• wiTECH or equivalent advanced scan tool: Restore Vehicle Configuration — This function is used before a Proxi Alignment to ensure the BCM has the correct factory configuration data to copy to the other modules on the network.
• Launch X431 or similar: Reset Shift Adaptives — While typically used for harsh shifting complaints, resetting the transmission's learned values can be a useful step after resolving communication issues to ensure the TCM relearns correctly. This can be done via a scan tool or a manual procedure.

Wiring & Ground Locations

• Star Connector (CAN Bus Hub) — Located behind the glove box, typically mounted to a bracket on the passenger side of the dash structure. The glove box must be removed for access.. This is the central junction point for the CAN bus network. The EGSM communicates through this connector. Poor pin tension or corrosion in this specific connector is a primary cause of U0103 and network-wide communication failures.
• EGSM Connector — Directly on the back of the rotary shifter module, which is part of the center stack instrument panel below the radio/HVAC controls.. This is the direct connection point for the module's power, ground, and CAN bus wires. It should be checked for secure connection, corrosion, and correct pin voltages.
• Main Chassis Grounds — Key grounds are located in the engine bay near the fuse box and on the chassis frame behind the headlights. On older Pacifica models, a ground point (G101) on a transmission stud was critical.. A poor ground connection for any module on the CAN bus, including the EGSM or BCM, can introduce electrical noise and cause communication failures across the network.

Real Owner Repair Stories

• YouTube channel 'BL Automotive' (2017 Chrysler Pacifica) — Check engine light on, tachometer jumping erratically, instrument panel chiming, electronic shifter going out, and multiple communication codes.
  ❌ Tried (didn't work) The dealership had thrown multiple parts at the vehicle without success. Using a multimeter was ineffective because it only averages the fluctuating CAN bus voltages.
  ✅ What actually fixed it The root cause was poor pin retention within the star connector behind the glove box. Wiggling the wires at the connector would make the problem appear and disappear, which was visible on an oscilloscope as corrupt data packets. The final fix was to replace the star connector block and re-pin the female connectors on the harness.
• YouTube channel 'World Mechanics' (Chrysler Pacifica (year not specified, but 2017+ body style)) — Shifter will not light up or turn, vehicle is stuck and won't shift. Multiple 'no communication' codes stored.
  ❌ Tried (didn't work) Slapping the top of the dashboard was a temporary fix that sometimes worked, indicating a loose connection.
  ✅ What actually fixed it The star connector behind the glove box had broken internal connection points. The entire star connector block was replaced to permanently resolve the issue. The video notes that in cold weather, the faulty connections contract and the problem becomes more frequent.

When the Usual Fixes Don't Work

• While many online forums suggest a simple battery disconnect can temporarily fix the issue, this often fails to address the root cause. In one case involving a similar platform, a user reported that disconnecting the battery worked initially, but the problem returned. Another user noted that low battery voltage can make the transmission modules sensitive and trigger the code, but the underlying issue was the battery's inability to hold a proper charge, not the shifter itself.

Model Year Variations Within This Range

• 2017 (built before Feb 15, 2017): These early-build 2017 models may have a software issue in the TCM that can cause U0103. Chrysler issued TSB 21-027-17 to address this with a software reflash, which should be checked before replacing any hardware. [S2408000065]
• 2021-2024: The 2021 model year introduced a significant interior and exterior refresh. This included a new center console design, a larger 10.1-inch touchscreen with the Uconnect 5 system, and updated LED lighting. While the fundamental rotary shifter and CAN bus architecture remain, the physical part numbers for the EGSM and surrounding trim may differ from pre-refresh models.