B1782

Code

Other B — Body

Mirror Passenger Up Circuit Failure

Brand: Other

Type: B — Body

Views: UK: 25 EN: 24 RU: 19

AI status

Completed

ready

Completed 100%

Page language: EN

Causes

Blown fuse or fusible link for mirror circuit
Open, shorted, or corroded wiring between mirror and control module
Poor or missing ground at mirror
Faulty passenger mirror motor/actuator
Faulty mirror position sensor or limit switch
Faulty mirror control switch

Symptoms

Passenger-side mirror fails to move to the up/fold position or does not respond
Mirror may not fold/unfold or may stop part way
DTC B1782 stored and may illuminate a body control warning (depending on vehicle)
Intermittent operation or require manual folding
Possible clicking from relay or module when commanded

What to check

Read and record all stored DTCs and freeze frame with an OEM-level scan tool
Attempt mirror up operation while monitoring live data for commanded state and feedback
Visually inspect fuse(s) and replace if blown
Inspect mirror harness and connectors for corrosion, pin damage, or water intrusion
Backprobe connector at mirror and module while operating to check for voltage/ground
Check ground continuity from mirror ground to chassis

Signal parameters

Command signal (when activated): battery voltage (~11–14 V) or switched ground depending on design
Inactive signal: near 0 V (if supply-type) or open/float depending on circuit
Motor coil resistance: typically low (few ohms to tens of ohms) — consult vehicle-specific spec
Control module output may be a switched ground or switched battery; expected change when command issued
No excessive voltage drop under load (significant drop indicates wiring or motor problem)

Diagnostic algorithm

Verify customer concern and confirm B1782 is current or stored. Record freeze frame and any related codes.
Inspect fuses and relays for mirror circuits; replace any blown fuses and retest.
Visually inspect passenger mirror assembly and harness for damage, corrosion, or water ingress. Repair as needed.
With key on and using a scan tool, command passenger mirror up while monitoring the output status of the BCM/mirror module and any feedback values.
Backprobe the mirror connector while commanding: verify presence of expected voltage or ground on the command pin and check return/feedback pins for proper signals.
Measure motor coil resistance at the mirror connector; compare to vehicle specification. Very high resistance or open indicates motor or internal wiring fault.
Check continuity between module connector and mirror connector; wiggle harness to check for intermittent opens. Repair any damaged wiring or connectors.
If wiring and connectors are good and proper command signals are present but motor does not operate, bench-test the mirror motor by applying appropriate battery voltage briefly (observe safety and avoid overheating). Replace mirror assembly if motor fails to respond or behaves erratically.
If there is no command from the control module, verify BCM power/ground and inputs (switch operation). Repair/replace the BCM only after verifying external wiring, switches, and mirror assembly are functional.
Clear codes, re-test the system through several cycles, and confirm the fault does not return.

Likely causes

Open or corroded wiring/connector between BCM and passenger mirror
Failed mirror motor or internal limit switch
Poor ground connection at mirror housing
Faulty mirror control switch or BCM output stage

Fault status

⚠️ Status

Control module detected a failure (open/short/incorrect feedback) in the passenger mirror 'up' circuit. The mirror did not respond with expected position or signal when commanded.

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 0.5-1.5 hours