AutoCodes – Generic – B1785

B1785 Code - Front Occupant Classification Sensor Left Collision Detection

Quick Answer

The Diagnostic Trouble Code (DTC) B1785 is output when the Occupant Detection ECU receives a collision detection signal sent by the Front Occupant Classification Sensor Left (LH) when an accident occurs. Common causes include Faulty Separate Type Front Seat Cushion Spring Assembly Left (Front Occupant Classification Sensor Left), Separate Type Front Seat Cushion Spring Assembly Left harness is open or shorted, Separate Type Front Seat Cushion Spring Assembly Left circuit poor electrical connection. Severity is High - diagnose this code as soon as possible. Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.

What it means: B1785 indicates Front Occupant Classification Sensor Left Collision Detection.
Common causes: Common causes include Faulty Separate Type Front Seat Cushion Spring Assembly Left (Front Occupant Classification Sensor Left), Separate Type Front Seat Cushion Spring Assembly Left harness is open or shorted, Separate Type Front Seat Cushion Spring Assembly Left circuit poor electrical connection.
Severity: High - diagnose this code as soon as possible.
Can I drive?: Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.

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Code Popularity 6,957

How popular is this code, among other codes? Low

Repair Importance Level

Urgent (Diagnose now) (3 / 3)

Repair Difficulty Level

Advanced (Pro) (3 / 3)

What is this?

Table of contents Created and updated by William Orellana on Oct 16, 2022

Description
Possible Causes
How To Fix
Cost to Diagnose
FAQs
Comments
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Code B1785 Description

The Diagnostic Trouble Code (DTC) B1785 is output when the Occupant Detection ECU receives a collision detection signal sent by the Front Occupant Classification Sensor Left (LH) when an accident occurs. DTC B1785 is also stored when the separate type of front seat cushion spring assembly is subjected to a strong impact, even if an actual accident has not occurred. However, when the Occupant Detection ECU outputs a collision detection signal, even if the vehicle is not in a collision, DTC B1785 can be cleared by performing the zero point calibration and sensitivity check. Therefore, when DTC B1785 is output, first perform the zero point calibration and sensitivity check.

OBDII Code B1785 - Front Occupant Classification Sensor Left Collision Detection - AutoCodes.com — B1785 Code - Front Occupant Classification Sensor Left Collision Detection

What does this mean?

What are the Possible Causes of the DTC B1785?

Faulty Separate Type Front Seat Cushion Spring Assembly Left (Front Occupant Classification Sensor Left)
Separate Type Front Seat Cushion Spring Assembly Left harness is open or shorted
Separate Type Front Seat Cushion Spring Assembly Left circuit poor electrical connection
Faulty Occupant Detection ECU

How to Fix the DTC B1785?

Review the 'Possible Causes' above and visually examine the corresponding wiring harness and connectors. Check for damaged components and inspect connector pins for signs of being broken, bent, pushed out, or corroded.

What is the Cost to Diagnose the Code?

Labor: 1.0

To diagnose the B1785 code, it typically requires 1.0 hour of labor. Rates vary by location, vehicle, and shop. Many shops charge between $80–$150 per hour; dealerships and metro areas may be higher, independents may be lower.

Need more information about the B1785 code?

Need more information on how to fix the B1785 code? Get Access to Factory Service Manuals

Need Help with the Code?

Get the B1785 code diagnosed by a professional: Find a repair shop in your area

Information for Specific Makes

B1785 Buick — Driver Seat Motor Recline Circuit
B1785 Cadillac — Driver Seat Motor Recline Circuit
B1785 Chevrolet — Driver Seat Motor Recline Circuit
B1785 GMC — Driver Seat Motor Recline Circuit
B1785 Lexus — Front Occupant Classification Sensor Left Collision Detection
B1785 Pontiac — Driver Seat Motor Recline Circuit
B1785 Saturn — Driver Seat Motor Recline Circuit
B1785 Scion — Front Occupant Classification Sensor Left Collision Detection
B1785 Toyota — Front Occupant Classification Sensor Left Collision Detection

Precautions for SRS “AIR BAG” and “SEAT BELT PRE-TENSIONER” Service

Never probe the electrical connectors on air bag, side air curtain modules or seat belts.
Never disassemble or tamper with safety belt buckle/retractor pretensioners, adaptive load limiting retractors, safety belt inflators, or probe the electrical connectors.
Do not use electrical test equipment to check SRS circuits unless instructed to in this Service Manual.
Before servicing the SRS, turn ignition switch OFF, disconnect both battery cables and wait at least 3 minutes. For approximately 3 minutes after the cables are removed, it is still possible for the air bag and seat belt pre-tensioner to deploy. Therefore, do not work on any SRS connectors or wires until at least 3 minutes have passed.

Failure to follow this instruction may result in the accidental deployment of these modules, which increases the risk of serious personal injury or death.

About the author: William Orellana is a Master Mechanic and Mechanical Engineer with over 30 years of experience diagnosing and repairing vehicles. Learn more about his background.

Frequently Asked Questions about B1785 Code

1. What are the common symptoms of OBDII code B1785 - Front Occupant Classification Sensor Left Collision Detection?

- Common symptoms include the airbag warning light illuminating on the dashboard and possible issues with the airbag system's functionality.

2. What are the possible causes of OBDII code B1785?

- The code B1785 may be triggered by a faulty front occupant classification sensor on the left side, wiring issues, or a malfunction in the airbag control module.

3. How can I diagnose the cause of OBDII code B1785?

- Diagnosis typically involves using a diagnostic scanner to retrieve the trouble codes, inspecting the front occupant classification sensor and its wiring for any visible damage, and performing any necessary tests as per the service manual.

4. Can I repair OBDII code B1785 on my own?

- While basic troubleshooting like checking connections and wiring can be done by DIY enthusiasts, it is recommended to have a professional technician diagnose and repair the issue to ensure proper functioning of the airbag system.

5. What are the potential risks of ignoring OBDII code B1785?

- Ignoring OBDII code B1785 can lead to the airbags not deploying in the event of a collision, potentially increasing the risk of injury to occupants in the vehicle.

6. How much does it typically cost to repair OBDII code B1785?

- The cost of repairing OBDII code B1785 can vary depending on the underlying cause, the extent of the damage, and the labor rates of the repair shop. It's advisable to get a few quotes from different mechanics to compare prices.

7. Can driving with OBDII code B1785 active cause further damage to my vehicle?

- While driving with the code active may not cause immediate harm to the vehicle, it is crucial to address the issue promptly to ensure the airbag system functions correctly in case of an accident.

8. Is it safe to continue driving my vehicle with OBDII code B1785 present?

- It is not recommended to continue driving the vehicle with OBDII code B1785 present, as the airbag system may not deploy as intended in the event of a collision, compromising the safety of the occupants.

9. How long does it typically take to repair OBDII code B1785?

- The repair time for OBDII code B1785 can vary depending on the exact cause of the issue and the availability of parts. In general, it may take a few hours to a day for a mechanic to diagnose and repair the problem.

10. Can a reset or clearing of the trouble codes fix OBDII code B1785?

- Clearing the trouble codes may temporarily turn off the warning light, but if the underlying issue causing OBDII code B1785 is not addressed, the code is likely to reappear. It is essential to diagnose and fix the root cause of the problem.