B1747 — Mirror Passenger Horizontal Switch Circuit Short To Battery

body electrical

Is it safe to drive?

Short-term driving is OK Usually safe to drive — body codes rarely affect drivability. Exceptions: exterior lighting and wipers in bad weather, and central locking faults that can leave the car unsecured.

How to diagnose with an OBD scanner

Read the code and freeze frame Connect an OBD2 scanner, confirm B1747 is stored, and save the freeze frame data — it shows engine conditions when the fault was detected.
Check for companion codes and TSBs Related codes often reveal the real root cause. Also check manufacturer technical service bulletins (TSB) for your make and model — many B0xxx issues have factory fixes or software updates. Search by VIN on the manufacturer site or nhtsa.gov.
Inspect wiring and connectors Visually inspect the wiring harness and connectors related to the body electrical system for damage, corrosion, chafing or poor contact.
Subsystem check Operate the affected function while watching its switch and motor PIDs in live data.
Subsystem check Inspect connectors and wiring at flex points (door jambs, tailgate hinges) — wires break there first.
Verify the repair Clear the code, complete a full drive cycle including the conditions from the freeze frame, and confirm B1747 does not return.

Approximate repair cost

Repair cost depends on which component actually failed. Typical scenarios for B1747 (parts and labor, USD, independent shop rates): BCM repair or replacement: $300–$900; Repair wiring or connectors: $80–$250; Replace the switch or actuator: $120–$450. Overall, fixing B1747 usually costs between $80 and $900. An accurate diagnosis before buying parts saves money — the most expensive scenario is rarely the first one to check.

Common questions

Will B1747 clear itself?

Sometimes B1747 clears after a few drive cycles if the fault was intermittent — for example a loose connector or a tank of bad fuel. The underlying cause usually remains, so the code tends to return. Clear it once; if it comes back, diagnose rather than erase it repeatedly.

What is the most common cause of B1747?

The most common causes are: corroded or loose connectors, body control module (BCM) fault, blown fuse or failed relay.

What are the symptoms of B1747?

Drivers most often notice: no impact on engine operation in most cases, the affected function (locks, windows, lighting, wipers) works intermittently or not at all, warning light on the dashboard.

What does OBD2 code B1747 mean?

Mirror Passenger Horizontal Switch Circuit Short To Battery (B1747): a body electrical fault affecting the body electrical system. The car is usually drivable while you plan the repair. Most often caused by corroded or loose connectors, body control module (BCM) fault, blown fuse or failed relay.

How do I diagnose B1747 myself?

Start with a scan: confirm B1747, save the freeze frame and note any companion codes. Then inspect the wiring and connectors related to the body electrical system, and verify the suspect component against live data before buying parts.

B1747 – Mirror Passenger Horizontal Switch Circuit Short to Battery

When your scan tool pulls code B1747, it is reporting a short circuit condition in the passenger-side mirror horizontal switch wiring — specifically, the circuit is finding battery voltage where it should not. This falls under the body electrical category in the OBD2 standard, which means the powertrain itself is unaffected. The body control module (BCM) monitors these switch inputs and expects a specific voltage range. When that range is violated because a wire is shorted to a constant 12-volt source, B1747 gets stored.

The module will not trigger the check engine light on a single glitch. Automotive control units are designed to confirm faults across multiple ignition cycles and under specific operating conditions before activating a warning. This confirmation requirement is why the freeze frame data saved alongside B1747 is valuable — it records engine load, RPM, coolant temperature, and vehicle speed at the exact moment the fault occurred. Use those readings to recreate the scenario during diagnosis. If B1747 keeps returning, you have an active short circuit that needs correction before the warning light behavior becomes unpredictable.

Common Symptoms of B1747

Most drivers notice no change in engine performance or fuel economy
The affected electrical function — whether mirrors, windows, locks, or lighting — operates intermittently or stops working entirely
An illuminated warning light on the instrument cluster
In some cases, multiple body functions share the same circuit, so several items may be affected simultaneously
Mirror adjustment in the horizontal direction fails while vertical adjustment continues working normally
The problem may come and go if the short is partial or if vibration changes the contact

What Causes B1747?

Damaged wiring running through door jambs or areas exposed to moisture — flexing and water intrusion are the two biggest wire killers in the door harness
A faulty passenger mirror horizontal switch or a failed motor inside the mirror assembly
Corroded or loose electrical connectors at the mirror, BCM, or any junction point in the affected circuit
A failed body control module that misinterprets the shorted input or cannot properly regulate the circuit
A blown fuse or failed relay that governs power distribution to the body electrical circuit
Wiring insulation that has cracked from age, heat cycling, or chemical exposure, allowing bare conductors to contact battery voltage

How to Diagnose B1747

Plug in an OBD2 scanner, retrieve B1747, and record the freeze frame data before clearing anything. This snapshot tells you what conditions were present when the module first flagged the fault.
Look for any accompanying diagnostic trouble codes. Related body codes often point to the root cause rather than a secondary effect. Check manufacturer TSB databases using your VIN — some B-series codes have published factory fixes or software calibrations.
Perform a hands-on visual inspection of the wiring harness running between the passenger door and the vehicle body. Focus on the door jamb area where wires flex with every open and close cycle.
Access the mirror switch and test it directly with a multimeter. Compare your readings against factory specifications for switch resistance and voltage at each switch position.
Examine all connectors in the circuit for bent pins, corrosion buildup, moisture intrusion, and terminal tension. Poor connection quality creates resistance that mimics short conditions.
After repairs, clear B1747 and complete a full drive cycle that recreates the freeze frame conditions. If the code does not return within several trips, the repair is confirmed.

Repair Options for B1747

The repair depends entirely on what is actually causing the short:

Wiring repair or connector replacement: $80–$250 — often the culprit when damage is visible in the door harness
Mirror switch or actuator replacement: $120–$450 — reasonable cost if testing confirms the switch itself is defective
BCM repair or replacement: $300–$900 — the most expensive option, and one you should not pursue until simpler causes are ruled out

How Much Does It Cost to Fix B1747?

A realistic total for B1747 diagnosis and repair, using independent shop labor rates in the United States, typically falls between $80 and $900. The wide range reflects the variety of possible causes. Wiring repairs sit at the low end, BCM replacement at the high end. Spending time with basic testing before buying expensive parts is strongly recommended — the least likely scenario should never be the first thing you replace.

Can You Drive with B1747?

Generally yes — body electrical faults rarely compromise engine operation, braking, or steering. The practical risk depends on what function is attached to the affected circuit. If the short happens to involve exterior lighting or windshield wipers and you are driving in rain or darkness, reduced visibility becomes a safety concern. Central locking faults tied to this circuit could leave the vehicle unsecured. Use common judgment: if your mirrors, lights, and locks are functioning acceptably, the car is drivable to the repair facility.