What Does P1816 Mean?
DTC P1816 indicates the 4-wheel drive low indicator circuit has a short to ground. The signal wire is being pulled low, preventing the indicator from showing 4WD-Low engagement. The driver will receive no visual confirmation when low-range is selected, which is particularly problematic in off-road or severe-duty situations where 4WD-Low is critical.
Common Causes
35%
Indicator wiring grounded against the chassis or undercarriage components
25%
Transfer case connector corrosion creating a ground path
20%
4WD low position switch internally grounded
10%
Harness damage from road debris or off-road impacts
10%
TCCM or instrument cluster internal ground fault
Diagnostic Steps
1
Disconnect the transfer case connector and check for continuity between the 4WD-Low indicator signal wire and ground; it should show open circuit.
2
If the short persists with the connector off, section-test the harness to locate the grounded segment.
3
Inspect the harness under the vehicle for damage from road debris, off-road impacts, or chafing on frame members.
4
Check the transfer case connector for water damage and green corrosion, especially at the signal pin.
5
Test the 4WD-Low position switch for internal shorts to the case ground.
Estimated Repair Cost
$60 - $350
Parts + labor, varies by vehicle and location
DTC P1816 indicates the 4-wheel drive low indicator circuit has a short to ground. The signal wire is being pulled low, preventing the indicator from showing 4WD-Low engagement. The driver will receive no visual confirmation when low-range is selected, which is particularly problematic in off-road o...
The most common cause of P1816 (Transmission 4-Wheel Drive Low Indicator Short Circuit To Ground) is: Indicator wiring grounded against the chassis or undercarriage components
Typical repair costs for P1816 range from $60 to $350, depending on the vehicle, location, and whether you do it yourself or go to a shop.
Without a working 4WD-Low indicator, the driver cannot confirm low-range engagement, which could result in driving at excessive speeds in low-range or attempting off-road obstacles without the needed gear reduction.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to P1816 to identify the root cause.
OBDHut Mobile App
Scan codes directly from your car with the OBDHut app.
Coming Soon
Quick Info
Category
Powertrain
System
Transfer Case / 4WD System
Difficulty
Type
Manufacturer
Recommended Tools
OBD2 Scanner
A quality scan tool helps you read codes, view live data, and clear faults.
