B1829 — Wiper Rear High Limit Input Circuit Short To Ground

OBD2 code B1829 flags a problem with the body electrical system (wiper rear high limit input circuit short to ground). The car is usually drivable while you plan the repair. Common culprits: body control module (BCM) fault, damaged wiring in door jambs or wet areas, faulty switch, motor or actuator of the affected system.

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 B1829 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 B1829 does not return.

Approximate repair cost

Repair cost depends on which component actually failed. Typical scenarios for B1829 (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 B1829 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 B1829 clear itself?

Sometimes B1829 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 B1829?

The most common causes are: body control module (BCM) fault, damaged wiring in door jambs or wet areas, faulty switch, motor or actuator of the affected system.

What are the symptoms of B1829?

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

What does OBD2 code B1829 mean?

How much does it cost to fix B1829?

BCM repair or replacement — $300–$900; Repair wiring or connectors — $80–$250; 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.

When the rear wiper motor is asked to run at full speed, the body control module expects to see a specific voltage signal come back through the high-limit input circuit. If that voltage never appears — because the circuit has been pulled to ground instead — the module logs trouble code B1829: "Wiper Rear High Limit Input Circuit Short To Ground." The fault lives in the body electrical category, not in the powertrain, so your engine will keep running normally.

The module relies on this feedback signal to confirm the motor actually reached high speed. When a short to ground corrupts the signal path, the control unit can no longer verify motor operation and defaults to a protective mode — often disabling the wiper entirely until the issue clears. Code B1829 typically needs to appear on two consecutive drive cycles before the check engine light illuminates, though some manufacturers trigger the warning immediately on the first occurrence. Either way, the stored freeze frame data captures engine speed, load, coolant temperature and vehicle speed the instant the problem happened, and that snapshot becomes your starting point for diagnosis.

Symptoms of B1829

The check engine or body-system warning light stays on
Rear wiper fails to operate or refuses to switch to high-speed mode
Intermittent wiper operation — works sometimes, then stops without warning
Wiper motor runs only at low speed regardless of switch position
No effect on engine performance, fuel delivery, or transmission function
Central locking or other body functions may behave erratically if a shared connector is involved

Common Causes of B1829

Shorted wiring behind the rear wiper motor connector — moisture intrusion and chafing are typical culprits
Faulty rear wiper motor with internal windings shorted to ground
Corroded or pushed-back pins in the wiper circuit connector
Defective multi-function switch on the steering column
Body control module itself malfunctioning and misinterpreting the signal
Blown fuse protecting the rear wiper circuit

How to Diagnose B1829

Plug in a compatible OBD2 scanner, retrieve code B1829, and record the associated freeze frame data before clearing anything — that snapshot tells you exactly what conditions triggered the fault.
Check for any other stored codes. Related body-system DTCs often point toward the actual root cause rather than just the symptom.
Visually trace the rear wiper wiring harness, paying close attention to the area near the tailgate hinge and the connector at the motor itself. Look for cracked insulation, green corrosion growth, or wires that have stretched and frayed.
Probe the high-limit signal circuit at the motor connector with a multimeter while commanding the wiper on. You should see reference voltage present; if you read continuity to ground instead, the short is confirmed.
Wiggle the harness at flex points while monitoring the multimeter — an intermittent short will show up as a fluctuating reading.
Clear B1829, operate the rear wiper through all its speeds, and run a complete drive cycle matching the freeze frame conditions. If the code returns, the short is still active.

Repair Options and Costs

If the wiring is simply damaged, repairing the shorted section or replacing the connector runs $80 to $250 depending on labor time and whether new terminals are needed. When the rear wiper motor itself has failed and is pulling the circuit to ground, expect to pay $120 to $450 for a new or remanufactured motor including installation. In the minority of cases where the body control module is at fault, BCM repair through a specialty shop typically costs $300 to $900, while dealership replacement can push toward the higher end or beyond depending on programming requirements.

Total Repair Cost for B1829

Most shops will quote between $80 and $250 for a wiring or connector fix, $120 to $450 for motor replacement, and $300 to $900 for BCM work. The wide range exists because the actual cause varies dramatically between vehicles. Spending time on a careful diagnosis before purchasing parts almost always keeps your total invoice under $500 — the BCM scenario is the exception, not the rule.

Can You Drive with B1829?

For most drivers, B1829 poses no drivability concern. The rear wiper is a convenience feature, and its failure does not affect braking, steering, or engine operation. However, consider the safety implications: reduced visibility in rain or snow if you rely on that wiper, and if the fault stems from water getting into connectors, the problem may spread to other body circuits over time. Addressing the code reasonably soon is still the smart move, even if the car remains street-legal in the meantime.