AutoCodes - Generic - U1804

U1804 Code - Lost Communication With Inside Rearview Mirror Control Module

Repair Importance Level: 3/3
Repair Difficulty Level: 3/3
Table of contents

|U1804 code possible causes

  • Faulty Inside Rearview Mirror Control Module
  • Inside Rearview Mirror Control Module harness is open or shorted
  • Inside Rearview Mirror Control Module circuit poor electrical connection

|How do I fix the U1804 code?

Check the "Possible Causes" listed above. Visually inspect the related wiring harness and connectors. Check for damaged components and look for broken, bent, pushed out, or corroded connector's pins.

|Cost of diagnosing the U1804 code

Labor: 1.0

The cost of diagnosing the U1804 code is 1.0 hour of labor. The auto repair's diagnosis time and labor rates vary by location, vehicle's make and model, and even your engine type. Most auto repair shops charge between $75 and $150 per hour.

|What are U1804 code possible symptoms?

  • Engine Light ON (or Service Engine Soon Warning Light)

|U1804 code description

Modules connected to the Controller Area Network (CAN) serial data circuits monitor for serial data communications during normal vehicle operation. Operating information and commands are exchanged among the modules. The modules have prerecorded information about what messages are needed to be exchanged on the serial data circuits. The messages are supervised and also, some periodic messages are used by the receiver module as an availability indication of the transmitter module. Each message contains the identification number of the transmitter module. A module with a CAN serial data circuits malfunction or which loses power during the current ignition cycle will have a Loss of Communication Diagnostic Trouble Code (DTC) set by other modules that depend on information from that failed module. If any of the CAN circuit are shorted to battery voltage, ground, or between them no communication is possible on the CAN serial data bus, a Diagnostic Trouble Code will set.
OBDII Code U1804 - Lost Communication With Inside Rearview Mirror Control Module - AutoCodes.com

|Need more information with the U1804 code?

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|U1804 code information for specific makes

  • U1804 BUICK Lost Communication With Inside Rearview Mirror Control Module
  • U1804 CADILLAC Lost Communication With Inside Rearview Mirror Control Module
  • U1804 CHEVROLET Lost Communication With Inside Rearview Mirror Control Module
  • U1804 GMC Lost Communication With Inside Rearview Mirror Control Module

|Need help with a U1804 code?

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|U1804 code comments

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Repair Importance Level: 3
 
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