Code
B1774
Other
B — Body
Mirror Driver Up Circuit Open
AI status
Completed
Completed
100%
Causes
- Open or broken wiring between body control module (BCM) and driver mirror
- Corroded or disconnected mirror connector pins
- Failed mirror control switch or joystick
- Failed mirror motor (up function) or internal motor connector open
- Blown fuse or poor power/ground supply to mirror circuit
- Faulty BCM or mirror control module (rare)
Symptoms
- Driver-side mirror will not move upward or respond to the up command
- Mirror may move in other directions but not up
- Stored B1774 DTC and possibly other mirror-related codes
- No audible motor noise from mirror when commanding Up
- Intermittent operation that sometimes clears with door movement
What to check
- Record freeze frame / current DTCs and any related mirror codes
- Visually inspect mirror housing connector and door harness at the hinge for damage, corrosion, or pin backout
- Check fuses related to mirror/BCM circuits
- Operate mirror Up command and listen for motor; observe behavior
- Scan tool: command mirror Up and monitor for any BCM/mirror module response or status messages
Signal parameters
- Expected battery supply: ~12–14 V when power present to mirror motor feed (verify with vehicle off/on as required)
- Mirror motor up command: switching to battery or ground depending on vehicle design (expect to see near 12 V or near 0 V on command pin)
- Motor coil resistance: typically a few ohms to tens of ohms (refer to vehicle-specific spec)
- Motor current while moving: may draw up to several amps; stall current higher — use clamp meter if available
- Communication: some vehicles use LIN/CAN for mirror position commands — expected module messages per manufacturer's specs
Diagnostic algorithm
- Record and clear codes, then attempt to re-create the fault to confirm persistence
- Perform visual inspection of driver door wiring, pinched harness at door hinge, and mirror connector for corrosion or broken pins
- Check relevant fuses and relays; replace if blown and re-test
- With connector disconnected, measure for battery voltage and ground at mirror power/ground pins while commanding Up from switch (use wiring diagram to identify pins)
- Check continuity between BCM/mirror control connector and mirror motor/switch pins; wiggle harness at hinge to check for intermittent opens
- If no voltage at mirror connector when commanded, test upstream (switch and BCM) outputs: verify switch continuity and BCM output with scan tool or backprobe
- If power/ground present at mirror connector but motor does not run, measure motor resistance and apply regulated 12 V directly to motor to test function (observe safety—do not exceed vehicle procedures)
- If motor works when directly powered, repair wiring/connectors between motor and BCM/switch; if motor does not run, replace mirror motor/assembly
- After repair, clear codes and verify mirror operation through multiple cycles and door positions; re-scan for codes
Likely causes
- Broken/shorted wire at door hinge (flex point) on driver side
- Corroded mirror connector at mirror housing
- Failed mirror up-limit switch or internal harness separation
- Failed mirror motor windings or internal connector open
Fault status
Status
Open circuit detected in driver-side mirror 'up' control circuit. Module not receiving expected electrical signal when Up is commanded.
Repair difficulty: Medium
Diagnostic time: 0.5-1.5 hours
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