AutoCodes – Generic – U2178

U2178 Code - Lost Communication With Trailer Interface Control Module

Quick Answer

Devices connected to the serial data circuits monitor for serial data communications during normal vehicle operation. Common causes include Faulty Trailer Interface Control Module, Trailer Interface Control Module harness is open or shorted, Trailer Interface Control Module circuit poor electrical connection. Severity is High - diagnose this code as soon as possible. Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.

What it means: U2178 indicates Lost Communication With Trailer Interface Control Module.
Common causes: Common causes include Faulty Trailer Interface Control Module, Trailer Interface Control Module harness is open or shorted, Trailer Interface Control Module circuit poor electrical connection.
Severity: High - diagnose this code as soon as possible.
Can I drive?: Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.

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Code Popularity 1,041

How popular is this code, among other codes? Low

Repair Importance Level

Urgent (Diagnose now) (3 / 3)

Repair Difficulty Level

Advanced (Pro) (3 / 3)

What is this?

Table of contents Created and updated by William Orellana on Jun 15, 2020

Description
Possible Causes
How To Fix
Cost to Diagnose
FAQs
Comments
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Code U2178 Description

Devices connected to the serial data circuits monitor for serial data communications during normal vehicle operation. Operating information and commands are exchanged among the devices. The devices have prerecorded information about what messages are needed to be exchanged on the serial data circuits, for each virtual network. The messages are supervised and also, some periodic messages are used by the receiver device as an availability indication of the transmitter device. Each message contains the identification number of the transmitter device. A loss of serial data communications Diagnostic Trouble Code (DTC) does not represent a failure of the devices that contain the stored code. The DTC will set when a supervised periodic message that includes the transmitter device availability has not been received.

OBDII Code U2178 - Lost Communication With Trailer Interface Control Module - AutoCodes.com — U2178 Code - Lost Communication With Trailer Interface Control Module

What does this mean?

What are the Possible Causes of the DTC U2178?

Faulty Trailer Interface Control Module
Trailer Interface Control Module harness is open or shorted
Trailer Interface Control Module circuit poor electrical connection

How to Fix the DTC U2178?

Review the 'Possible Causes' above and visually examine the corresponding wiring harness and connectors. Check for damaged components and inspect connector pins for signs of being broken, bent, pushed out, or corroded.

What is the Cost to Diagnose the Code?

Labor: 1.0

To diagnose the U2178 code, it typically requires 1.0 hour of labor. Rates vary by location, vehicle, and shop. Many shops charge between $80–$150 per hour; dealerships and metro areas may be higher, independents may be lower.

Need more information about the U2178 code?

Need more information on how to fix the U2178 code? Get Access to Factory Service Manuals

Need Help with the Code?

Get the U2178 code diagnosed by a professional: Find a repair shop in your area

Information for Specific Makes

U2178 Buick — Lost Communication With Trailer Interface Control Module
U2178 Cadillac — Lost Communication With Trailer Interface Control Module
U2178 Chevrolet — Lost Communication With Trailer Interface Control Module
U2178 GMC — Lost Communication With Trailer Interface Control Module

About the author: William Orellana is a Master Mechanic and Mechanical Engineer with over 30 years of experience diagnosing and repairing vehicles. Learn more about his background.

Frequently Asked Questions about U2178 Code

1. What does the OBDII code U2178 mean?

U2178 indicates that the vehicle's main control module has lost communication with the Trailer Interface Control Module (TICM), which manages trailer-related functions.

2. What are the symptoms of code U2178?

Symptoms may include trailer lights or brakes not functioning, warning messages on the dashboard, and potentially inoperative trailer detection.

3. What causes the U2178 code to appear?

Common causes include faulty or disconnected wiring, a malfunctioning Trailer Interface Control Module, a blown fuse, or software issues in the vehicle's control systems.

4. Can I still drive my vehicle with code U2178 active?

Yes, you can drive the vehicle, but trailer-related features may not work properly, which can be unsafe if youâ€™re towing a trailer.

5. How do I diagnose a U2178 code?

Start by inspecting the wiring and connectors to the Trailer Interface Control Module, checking for corrosion, damage, or loose connections. Test the module itself and verify that the fuses are intact.

6. Is a faulty Trailer Interface Control Module the only cause of U2178?

No, other potential causes include issues with the vehicleâ€™s CAN communication network, software glitches, or power supply problems to the module.

7. How much does it cost to repair the U2178 code?

The cost depends on the root cause. Repairs can range from $50 for simple wiring fixes to $500 or more for replacing the Trailer Interface Control Module.

8. Can resetting the code fix U2178?

Resetting the code might temporarily clear it, but if the underlying issue isnâ€™t resolved, the code will reappear.

9. Do I need special tools to fix the U2178 code?

Yes, diagnostic tools like an advanced OBDII scanner with CAN communication capabilities are recommended to properly diagnose and troubleshoot this issue.

10. What happens if I ignore the U2178 code?

Ignoring the code may lead to continued malfunction of trailer-related systems, potentially compromising safety when towing a trailer.