What Does B1782 Mean?
B1782 indicates the Body Control Module (BCM) has detected a circuit malfunction in the passenger side mirror upward movement control. The BCM monitors voltage and current flow in the mirror motor circuit and has identified either an open circuit, short circuit, or excessive resistance preventing proper upward mirror adjustment. This is a manufacturer-specific body system code affecting the power mirror control system.
Common Causes
35%
Faulty passenger side mirror motor assembly with internal winding failure or brush wear in the upward direction circuit
30%
Broken or corroded wiring between BCM and passenger mirror, particularly in door hinge area where wires flex repeatedly
20%
Corroded or loose electrical connector at passenger mirror or BCM with high resistance contact
10%
Failed Body Control Module with damaged mirror control output driver circuit
5%
Damaged mirror switch assembly sending incorrect signals or creating short circuit condition
Diagnostic Steps
1
Step 1: Perform visual inspection of passenger mirror wiring harness from door jamb through door panel, checking for pinched, cut, or chafed wires. Pay special attention to the door hinge area where wires flex during door operation.
2
Step 2: Using a digital multimeter, test for voltage at the passenger mirror connector while commanding mirror upward movement. Expect 12V at the appropriate terminal when activated; lack of voltage indicates BCM or wiring issue upstream.
3
Step 3: Disconnect mirror connector and measure resistance across the mirror motor terminals for the upward circuit. Normal resistance should be 2-10 ohms; infinite resistance indicates open motor winding, near-zero indicates short circuit.
4
Step 4: Check for continuity between BCM connector and mirror connector on the upward control circuit wire. Wiggle harness during testing to expose intermittent breaks. Resistance should be less than 0.5 ohms.
5
Step 5: If wiring tests good, apply 12V directly to mirror motor upward circuit terminals using a fused jumper wire to verify motor operation. If mirror moves properly, suspect BCM output failure.
6
Step 6: Clear codes, verify repair by operating mirror through full range of motion multiple times, and confirm no code returns after test drive including door cycling.
Estimated Repair Cost
$120 - $650
Parts + labor, varies by vehicle and location
B1782 indicates the Body Control Module (BCM) has detected a circuit malfunction in the passenger side mirror upward movement control. The BCM monitors voltage and current flow in the mirror motor circuit and has identified either an open circuit, short circuit, or excessive resistance preventing pr...
The most common cause of B1782 (Mirror Passenger Up Circuit Failure) is: Faulty passenger side mirror motor assembly with internal winding failure or brush wear in the upward direction circuit
Typical repair costs for B1782 range from $120 to $650, 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 feature and does not impact vehicle operation or safety systems. Repair at convenience unless mirror is stuck in an unsafe position that impairs rear visibility, in which case manual adjustment or prompt repair is recommended.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to B1782 to identify the root cause.
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Quick Info
Category
Body
System
Body Control and Convenience Systems
Difficulty
Type
Manufacturer
Recommended Tools
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