U1804
Lost Communication With Inside Rearview Mirror Control Module
U1804 is an OBD-II diagnostic trouble code meaning: Lost Communication With Inside Rearview Mirror Control Module. Common causes: open or short circuit in the module power supply circuit, damage to the wiring harness to the mirror. Estimated repair cost: $17–89.
Symptoms
- Automatic mirror dimming functions do not work
- Lack of compass readings on the mirror (if provided)
- The rear view camera display does not work (if displayed on the mirror)
- Malfunction indicator lamp on the dashboard
- The error is stored in the ECU memory
Causes
- Open or short circuit in the module power supply circuit
- Damage to the wiring harness to the mirror
- Mirror control module malfunction
- Poor contact in connectors
- Blown mirror circuit fuse
How to Fix
- Check the fuse of the corresponding circuit
- Inspect the wiring harness and connectors for damage.
- Check power and ground at the mirror module connector
- Scan the mirror module for additional errors
- If necessary, replace the mirror control module
Related codes
FAQ
What does the U1804 code mean?
U1804 is an OBD-II diagnostic trouble code that indicates: Lost Communication With Inside Rearview Mirror Control Module
What causes a U1804 error code?
The most common causes of U1804 include: Open or short circuit in the module power supply circuit; Damage to the wiring harness to the mirror; Mirror control module malfunction; Poor contact in connectors.
How do I fix a U1804 diagnostic trouble code?
To fix U1804: Check the fuse of the corresponding circuit. Inspect the wiring harness and connectors for damage.. Check power and ground at the mirror module connector. For a complete diagnosis, use an OBD-II scanner.
Is it safe to drive with U1804?
Yes, but get it checked soon
How much does it cost to fix U1804?
The estimated repair cost for U1804 is $17–89. Actual cost depends on your vehicle, location, and labor rates.
See also: Russian version · NationStat