B1477 — Wiper Hi/Low Circuit Motor Short To Ground

OBD2 code B1477 flags a problem with the body electrical system (wiper hi/low circuit motor short to ground). The car is usually drivable while you plan the repair. Common culprits: body control module (BCM) fault, faulty switch, motor or actuator of the affected system, blown fuse or failed relay.

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 B1477 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 B1477 does not return.

Approximate repair cost

Repair cost depends on which component actually failed. Typical scenarios for B1477 (parts and labor, USD, independent shop rates): Repair wiring or connectors: $80–$250; BCM repair or replacement: $300–$900; Replace the switch or actuator: $120–$450. Overall, fixing B1477 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

How much does it cost to fix B1477?

Repair wiring or connectors — $80–$250; BCM repair or replacement — $300–$900; Replace the switch or actuator — $120–$450. Exact cost depends on the root cause, your vehicle and local labor rates — a proper diagnosis is the cheapest first step.

How do I diagnose B1477 myself?

Start with a scan: confirm B1477, 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.

What does OBD2 code B1477 mean?

What is the most common cause of B1477?

The most common causes are: body control module (BCM) fault, faulty switch, motor or actuator of the affected system, blown fuse or failed relay.

Will B1477 clear itself?

Sometimes B1477 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.

The engine control module logs code B1477 when it finds a short to ground in the wiper hi/low motor circuit. This isn't an engine problem — it's a body electrical issue that falls under the OBD2 generic code family B1xxx, which covers body and chassis systems. When the wiper motor circuit draws current to ground through an unintended path, the module detects the abnormal signature and flags B1477.

The body control module (BCM) constantly watches voltage and current flow through the wiper motor circuit. It expects the motor to respond only when commanded. When a short develops — typically from damaged insulation, water intrusion, or a failed connector — current bleeds to ground without the BCM's permission. Over one or more drive cycles, this pattern triggers the fault. The BCM also captures a freeze frame at the moment of detection, recording engine speed, load, coolant temperature, and vehicle speed. That snapshot is valuable: it tells you exactly what conditions were present when B1477 went active, which helps you reproduce the failure during testing.

Symptoms of B1477

Dashboard warning light or illuminated service indicator
Wipers operate at one speed only, or fail to switch between hi and lo
Wiper motor runs continuously or not at all when commanded
Intermittent operation — works sometimes, then stops
Other body functions (windows, locks, lighting) may behave erratically if the BCM is involved
No loss of engine power, acceleration, or fuel economy

Causes of B1477

Blown fuse or faulty relay — the most common trigger; power never reaches the motor in the first place
Damaged wiring in door jambs or wet areas — flex points crack and short to ground
Corroded or loose connectors — especially at the wiper motor or multifunction switch
Body control module failure — less common but possible if multiple body codes appear
Failed wiper switch or actuator — internal short in the command device
Water intrusion into the motor housing — causes temporary or permanent shorts
Aftermarket accessory wiring errors — incorrectly installed additions can backfeed the circuit

How to Diagnose B1477

Pull the code with an OBD2 scanner — confirm B1477 is stored and record the freeze frame data before clearing anything. That data shows engine conditions at the moment of failure.
Check for related codes — B1400 through B1405 codes often appear alongside B1477, pointing to a broader body electrical issue. Also search for TSBs on nhtsa.gov or your manufacturer's site using your VIN; some B1xxx codes have known fixes or BCM software updates.
Inspect the fuse and relay — this takes seconds and is the cheapest first step. Swap the wiper fuse with a known good one and test operation.
Visually trace the wiring — focus on the firewall passthrough, door jambs, and any connectors near the wiper motor. Look for cracked insulation, corrosion, or wires that have pulled free.
Use live data — command the wipers on and monitor voltage at the motor connector while watching the switch PIDs. If the BCM shows the command but voltage doesn't change at the motor, the problem is downstream.
Clear the code and road-test — run a complete drive cycle under the same conditions recorded in the freeze frame. If B1477 returns, you've confirmed a hard fault rather than an intermittent one.

Repair Options and Costs

Prices reflect typical U.S. independent shop rates for parts and labor:

Fuse or relay replacement — $15–$40 parts alone; labor minimal if accessible
Wiring repair or connector replacement — $80–$250 depending on damage extent and labor time
Wiper switch or motor replacement — $120–$450 depending on make and labor access
BCM repair or replacement — $300–$900; BCM programming may be required by a dealership

Total Cost to Fix B1477

Expect to spend between $80 and $900 depending on which component is at fault. Most cases resolve around the $150–$300 range when the issue is a fuse, relay, or wiring damage. BCM replacement pushes toward the high end and should only be considered after ruling out every other possibility. Always diagnose before you buy — swapping a $700 BCM when the problem is a $20 fuse is an expensive lesson.

Can You Drive with B1477?

Severity level: short. This code does not affect engine performance, emissions, or safety systems in most vehicles. You can continue driving, but rain or inclement weather becomes a safety concern if the wipers are inoperable or stuck on high speed. Central locking faults associated with broader BCM issues can leave the vehicle unsecured. Address B1477 before prolonged bad weather or long trips.