What Does P1806 Mean?
DTC P1806 indicates the 4-wheel drive high indicator circuit has a short to battery voltage. The transfer case control module or instrument cluster is seeing a constant high signal on the 4WD-High indicator line, which may cause the 4WD indicator to remain illuminated regardless of the actual transfer case position.
Common Causes
35%
Shorted wiring in the 4WD indicator circuit contacting a power source
25%
Internally shorted 4WD high position switch
15%
Aftermarket lighting or accessories spliced into the indicator circuit
15%
Connector pin cross-contact with an adjacent power circuit
10%
Transfer case control module output driver failure
Diagnostic Steps
1
Disconnect the transfer case connector and recheck for the fault; if it clears, the switch or transfer case internal harness is the issue.
2
With the connector disconnected, check for battery voltage on the signal wire at the module side; voltage present indicates a harness short to power.
3
Inspect the wiring from the transfer case to the TCCM for chafing or damage, especially where it runs near power feeds.
4
Test the 4WD high position switch for proper resistance values in both the engaged and disengaged states.
5
Check for any aftermarket accessories that may be tapped into the 4WD indicator circuit.
Estimated Repair Cost
$75 - $400
Parts + labor, varies by vehicle and location
DTC P1806 indicates the 4-wheel drive high indicator circuit has a short to battery voltage. The transfer case control module or instrument cluster is seeing a constant high signal on the 4WD-High indicator line, which may cause the 4WD indicator to remain illuminated regardless of the actual transf...
The most common cause of P1806 (Transmission 4-Wheel Drive High Indicator Short Circuit To Battery) is: Shorted wiring in the 4WD indicator circuit contacting a power source
Typical repair costs for P1806 range from $75 to $400, depending on the vehicle, location, and whether you do it yourself or go to a shop.
A falsely illuminated 4WD indicator can mislead the driver about the active drivetrain mode, potentially leading to inappropriate driving behavior or driveline binding.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to P1806 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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