What Does P1804 Mean?
DTC P1804 indicates a circuit failure in the 4-wheel drive high indicator circuit within the transmission/transfer case control system. The TCM or transfer case control module cannot properly communicate the 4WD-High engagement status to the instrument cluster or other modules. This may cause the 4WD indicator to be inoperative or display incorrectly.
Common Causes
30%
Faulty 4WD high indicator switch in the transfer case
25%
Broken or corroded wiring in the indicator circuit
20%
Damaged transfer case connector
15%
Failed instrument cluster indicator driver
10%
Transfer case control module fault
Diagnostic Steps
1
Verify whether the 4WD High indicator lamp illuminates during the bulb check at key-on; if not, check the bulb and instrument cluster.
2
Engage 4WD High and use a scan tool to read the transfer case status PIDs; verify the module sees the correct mode.
3
Inspect the transfer case electrical connector for corrosion, moisture, and secure fitment.
4
Test the 4WD high position switch at the transfer case with an ohmmeter; it should close when 4WD-High is engaged.
5
Check the wiring between the transfer case switch and the TCCM/instrument cluster for continuity and shorts.
Estimated Repair Cost
$75 - $400
Parts + labor, varies by vehicle and location
DTC P1804 indicates a circuit failure in the 4-wheel drive high indicator circuit within the transmission/transfer case control system. The TCM or transfer case control module cannot properly communicate the 4WD-High engagement status to the instrument cluster or other modules. This may cause the 4W...
The most common cause of P1804 (Transmission 4-Wheel Drive High Indicator Circuit Failure) is: Faulty 4WD high indicator switch in the transfer case
Typical repair costs for P1804 range from $75 to $400, depending on the vehicle, location, and whether you do it yourself or go to a shop.
While primarily an indicator issue, incorrect 4WD status feedback can lead the driver to unknowingly operate in the wrong drivetrain mode, potentially causing driveline binding on dry pavement.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to P1804 to identify the root cause.
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Quick Info
Category
Powertrain
System
Transfer Case / 4WD System
Difficulty
Type
Manufacturer
Recommended Tools
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