What Does B1774 Mean?
This code indicates the Body Control Module (BCM) has detected an open circuit in the driver's side mirror upward movement control circuit. The BCM commanded the mirror to move upward but detected no current flow or infinite resistance in the circuit, suggesting a break in the wiring, a faulty connection, or a failed mirror motor. This prevents the driver's mirror from tilting upward when commanded via the mirror control switch.
Common Causes
40%
Open or broken wire between BCM and driver's mirror motor, often due to flexing in the door hinge area
30%
Failed driver's side mirror motor assembly with open upward movement circuit
20%
Corroded or loose connector at mirror motor or BCM connection points
10%
Faulty BCM with failed mirror control output driver circuit
Diagnostic Steps
1
Step 1: Perform a visual inspection of the driver's door wiring harness, particularly in the door hinge area where wires flex during opening/closing. Check for broken, chafed, or damaged wires and inspect all connectors for corrosion, pushed-out pins, or looseness.
2
Step 2: Using a digital multimeter, backprobe the mirror motor connector while attempting to move the mirror upward using the control switch. Check for battery voltage (typically 12V) on the 'up' circuit wire. If no voltage is present, the fault is between the BCM and mirror; if voltage is present, the mirror motor is likely faulty.
3
Step 3: Disconnect the mirror motor connector and measure resistance across the mirror motor's upward movement terminals. Compare readings to manufacturer specifications (typically 5-15 ohms). An open circuit (infinite resistance) confirms mirror motor failure.
4
Step 4: If wiring and mirror motor test good, check continuity from the BCM connector to the mirror motor connector on the upward control circuit with all connectors disconnected. Repair any open circuits found in the harness.
5
Step 5: After repairs, reconnect all components, clear the code, and cycle the mirror through all positions multiple times to verify proper operation and confirm the code does not return.
Estimated Repair Cost
$100 - $450
Parts + labor, varies by vehicle and location
This code indicates the Body Control Module (BCM) has detected an open circuit in the driver's side mirror upward movement control circuit. The BCM commanded the mirror to move upward but detected no current flow or infinite resistance in the circuit, suggesting a break in the wiring, a faulty conne...
The most common cause of B1774 (Mirror Driver Up Circuit Open) is: Open or broken wire between BCM and driver's mirror motor, often due to flexing in the door hinge area
Typical repair costs for B1774 range from $100 to $450, depending on the vehicle, location, and whether you do it yourself or go to a shop.
Safe to continue driving as this only affects mirror adjustment convenience and does not impact vehicle operation or safety systems. Repair at your convenience, though proper mirror adjustment is important for safe lane changes and backing maneuvers.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to B1774 to identify the root cause.
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Quick Info
Category
Body
System
Body Control and Accessories
Difficulty
Type
Manufacturer
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