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U0102 on Buick: Symptoms, Causes & Fix

Lost Communication with Transfer Case Control Module (TCCM)

Official technical diagnostic wire for fault code U0102 specifically affecting Buick vehicles (Enclave, Encore GX, Envision, Envista).

Sensor Voltage Ref
0.1V – 5.0V Ref
Buick Factory Standard
CAN Bus Speed
500 kbps CAN-FD
ISO 15765-4 Diagnostic Bus
Drivability Status
Drivable (Short Trip)
Medium urgency level
Est. Repair Cost
$150 - $650 (DIY: $50 - $220)
Parts & Labor DIY
Model-Specific Diagnostic Wires

Select Your Buick Model for U0102:

4 Models Available
Buick Enclave2020–2026
Buick EnclaveSUV • 3.6L V6 (310HP) / 2.5L Turbo 4-Cyl (328HP)
U0102 Fix & DLC Location
Buick Encore GX2020–2026
Buick Encore GXSUV • 1.2L Turbo 3-Cyl (137HP) / 1.3L Turbo 3-Cyl (155HP)
U0102 Fix & DLC Location
Buick Envision2021–2026
Buick EnvisionSUV • 2.0L Turbo 4-Cyl (228HP / 258 lb-ft AWD)
U0102 Fix & DLC Location
Buick Envista2024–2026
Buick EnvistaSUV • 1.2L ECOTEC Turbo 3-Cyl (137HP / 162 lb-ft)
U0102 Fix & DLC Location

1. Common Symptoms on Buick Vehicles

When Buick Engine Control Modules (ECM) trigger fault code U0102, drivers typically report:

'Service 4WD' or '4WD System Error' message on dash on Buick Powertrains
4WD selector switch unresponsive (lights out on switch) on Buick Powertrains
Vehicle stuck in 2WD or last selected 4WD mode on Buick Powertrains

2. Root Causes on Buick Engines

Historical diagnostic claims across Buick engines point to the following failure distribution:

55%
Corroded TCCM power/ground wiring under vehicle (Buick OEM Part)
25%
Blown 4WD / TCCM fuse in engine fuse panel (Buick OEM Part)
12%
Faulty Transfer Case Control Module (Buick OEM Part)
8%
Faulty transfer case shift encoder motor (Buick OEM Part)

3. Step-by-Step Fix Protocol for Buick

01
Check 4WD / TCCM Fuses

Inspect ATC / 4WD fuses with test light. on Buick engines.

Required Tool: Test Light
02
Inspect TCCM Connector

Check module under driver dash or seat for water intrusion. on Buick engines.

Required Tool: Flashlight
03
Test CAN Bus Wires at TCCM

Verify 2.5V CAN signals reach the module. on Buick engines.

Required Tool: Multimeter
04
Replace TCCM & Clear Codes

Install replacement module and clear trouble codes. on Buick engines.

Required Tool: Socket Set, Scan Tool
Recommended Parts & Testing Tools

Equipment for Diagnosing Buick (U0102)

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Direct-Fit Replacement Part

Buick OEM Replacement Sensor

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Direct-fit replacement assembly engineered to OEM tolerances for Buick.

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Sensor Signal Voltage Meter

AstroAI Auto-Ranging Digital Multimeter

4.6 / 5.0 (Best Seller)

Essential for testing 0.1V–5.0V sensor reference signals, ground continuity (<0.20Ω), and harness resistance.

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4. Buick U0102 Frequently Asked Questions

What does code U0102 mean on a Buick?

On Buick vehicles, U0102 indicates that the Engine Control Module (ECM) detected lost communication with transfer case control module (tccm). This typically points to Corroded TCCM power/ground wiring under vehicle or Blown 4WD / TCCM fuse in engine fuse panel.

Can I continue driving my Buick with code U0102?

Yes, in 2WD. 4WD and Auto 4x4 functions will be inoperative. Because this code carries a Medium severity rating on Buick powertrains, we recommend scanning live data values promptly to prevent secondary damage.

How much does it cost to fix code U0102 on a Buick?

Estimated DIY parts cost ranges from $150 - $650 (DIY: $50 - $220), while professional shop repairs at an authorized Buick dealership or independent specialist typically range from $180 to $380 including diagnostic labor.