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U0102 on Cadillac Lyriq

Lost Communication with Transfer Case Control Module (TCCM)

Factory diagnostic protocol and troubleshooting wire for fault code U0102 specifically for the Cadillac Lyriq (2023–2026, Ultium Dual Motor AWD (500HP / 450 lb-ft) / Single Motor RWD (340HP)).

Verified OEM Telemetry & Field Repair Tree
Cadillac Lyriq2023–2026
Cadillac Lyriq
EVUltium Dual Motor AWD (500HP / 450 lb-ft) / Single Motor RWD (340HP)
Reliability
Sensor Voltage Ref
0.1V – 5.0V Ref
Lyriq SAE Mode $01
ECU Network Bus
500 kbps CAN-FD
ISO 15765-4 Compliant
Drivability Status
Drivable (Short Trip)
Medium urgency level
Est. Repair Cost
$150 - $650 (DIY: $50 - $220)
Parts & Labor DIY
Check U0102 On Another Cadillac Model:
Diagnose U0102 on Specific Lyriq Model Year:

1. Symptoms of U0102 on Cadillac Lyriq

When the Engine Control Module (ECM/PCM) on your Cadillac Lyriq (Ultium Dual Motor AWD (500HP / 450 lb-ft) / Single Motor RWD (340HP)) logs fault code U0102, drivers commonly observe:

'Service 4WD' or '4WD System Error' message on dash on Cadillac Lyriq (Ultium Dual Motor AWD (500HP / 450 lb-ft) / Single Motor RWD (340HP))
4WD selector switch unresponsive (lights out on switch) on Cadillac Lyriq (Ultium Dual Motor AWD (500HP / 450 lb-ft) / Single Motor RWD (340HP))
Vehicle stuck in 2WD or last selected 4WD mode on Cadillac Lyriq (Ultium Dual Motor AWD (500HP / 450 lb-ft) / Single Motor RWD (340HP))
Cadillac Lyriq OBD-II Port Location
The 16-pin diagnostic connector is located Under driver steering column beneath knee bolster. Plug in your scan tool to verify freeze-frame sensor values.

2. Most Likely Causes on Cadillac Lyriq

Historical warranty claims and technical repair bulletins for Cadillac Lyriq point to the following failure distribution:

55%
Corroded TCCM power/ground wiring under vehicle (Cadillac OEM Part)
25%
Blown 4WD / TCCM fuse in engine fuse panel (Cadillac OEM Part)
12%
Faulty Transfer Case Control Module (Cadillac OEM Part)
8%
Faulty transfer case shift encoder motor (Cadillac OEM Part)
* Source: Synthesized from NHTSA ODI field repair telemetry and verified OEM Technical Service Bulletin (TSB) repair tree frequency percentiles for Cadillac Lyriq.

3. Step-by-Step DIY Repair Guide for Cadillac Lyriq

01
Check 4WD / TCCM Fuses

Inspect ATC / 4WD fuses with test light. on the Cadillac Lyriq equipped with Ultium Dual Motor AWD (500HP / 450 lb-ft) / Single Motor RWD (340HP).

Required Tool: Test Light
02
Inspect TCCM Connector

Check module under driver dash or seat for water intrusion. on the Cadillac Lyriq equipped with Ultium Dual Motor AWD (500HP / 450 lb-ft) / Single Motor RWD (340HP).

Required Tool: Flashlight
03
Test CAN Bus Wires at TCCM

Verify 2.5V CAN signals reach the module. on the Cadillac Lyriq equipped with Ultium Dual Motor AWD (500HP / 450 lb-ft) / Single Motor RWD (340HP).

Required Tool: Multimeter
04
Replace TCCM & Clear Codes

Install replacement module and clear trouble codes. on the Cadillac Lyriq equipped with Ultium Dual Motor AWD (500HP / 450 lb-ft) / Single Motor RWD (340HP).

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

Equipment for Diagnosing Cadillac Lyriq (U0102)

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Direct-Fit Replacement Part

Cadillac Lyriq OEM Replacement Sensor

4.7 / 5.0 (Verified Fit)

Direct-fit replacement assembly engineered to OEM tolerances for Cadillac Lyriq.

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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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Top Mobile OBD-II Scanner

BlueDriver Bluetooth Pro OBDII Scan Tool

4.7 / 5.0 (50,000+ Reviews)

Reads and clears enhanced codes (ABS, Airbag, Transmission, Engine) & live freeze-frame telemetry on phone.

Compare OEM & Aftermarket Replacement Sensors for Cadillac LyriqVerified direct-fit pricing from Denso, Bosch, Motorcraft, and ACDelco on Amazon.
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Other Common Fault Codes on Cadillac Lyriq

Frequently diagnosed powertrain, emissions, and sensor trouble codes logged on the Cadillac Lyriq:

4. Cadillac Lyriq U0102 FAQs

What causes code U0102 to trigger on a Cadillac Lyriq?

On the Cadillac Lyriq (Ultium Dual Motor AWD (500HP / 450 lb-ft) / Single Motor RWD (340HP)), U0102 is most frequently caused by Corroded TCCM power/ground wiring under vehicle or Blown 4WD / TCCM fuse in engine fuse panel.

Where is the OBD-II port located on my Cadillac Lyriq?

On the Cadillac Lyriq, the 16-pin DLC diagnostic connector is located Under driver steering column beneath knee bolster. Plug in any standard OBD-II scanner with the ignition in the ON position to read freeze-frame parameters.

Can I safely drive my Cadillac Lyriq with code U0102?

Yes, in 2WD. 4WD and Auto 4x4 functions will be inoperative. Given that U0102 carries a Medium severity rating, we advise avoiding heavy towing or aggressive throttle inputs until sensor readings are verified.