AutoCodes – Generic – U1816

U1816 Code - Lost Communication With Drive Motor Control Module B On Bus B

Quick Answer

Devices connected to the powertrain high-speed General Motor Local Area Network (GMLAN) serial data circuits monitor for serial data communications during normal vehicle operation. Common causes include Faulty Drive Motor Control Module B, Drive Motor Control Module B harness is open or shorted, Drive Motor Control Module B 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: U1816 indicates Lost Communication With Drive Motor Control Module B On Bus B.
Common causes: Common causes include Faulty Drive Motor Control Module B, Drive Motor Control Module B harness is open or shorted, Drive Motor Control Module B 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.

Save to My Repairs My Repairs

AI answers can be wrong. Verify repairs with testing. Open full chat

Code Popularity 730

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 07, 2020

Description
Possible Causes
How To Fix
Cost to Diagnose
Comments
Add Comment

💬 Need more help? Ask Coddy for instant answers — it's free!

Code U1816 Description

Devices connected to the powertrain high-speed General Motor Local Area Network (GMLAN) 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.
The Diagnostic Trouble Code (DTC) will set when a supervised periodic message that includes the transmitter device availability has not been received.

OBDII Code U1816 - Lost Communication With Drive Motor Control Module B On Bus B - AutoCodes.com — U1816 Code - Lost Communication With Drive Motor Control Module B On Bus B

What does this mean?

What are the Possible Causes of the DTC U1816?

Faulty Drive Motor Control Module B
Drive Motor Control Module B harness is open or shorted
Drive Motor Control Module B circuit poor electrical connection

How to Fix the DTC U1816?

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 U1816 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 U1816 code?

Need more information on how to fix the U1816 code? Get Access to Factory Service Manuals

Need Help with the Code?

Get the U1816 code diagnosed by a professional: Find a repair shop in your area

Information for Specific Makes

U1816 Buick — Lost Communication With Drive Motor Control Module B On Bus B
U1816 Cadillac — Lost Communication With Drive Motor Control Module B On Bus B
U1816 Chevrolet — Lost Communication With Drive Motor Control Module B On Bus B
U1816 GMC — Lost Communication With Drive Motor Control Module B On Bus B

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.