B1878 Code - Short to Positive in Passenger Side Front Seat Cushion Squib Circuit

Quick Answer

The diagnostic trouble code B1878 indicates a short to positive in the passenger side front seat cushion squib circuit. Common causes include Wiring issues or damaged wiring harness in the passenger side front seat cushion squib circuit, Faulty seat cushion squib, Corrosion or loose connections in the circuit. 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

B1878 indicates Short to Positive in Passenger Side Front Seat Cushion Squib Circuit.

Common causes

Common causes include Wiring issues or damaged wiring harness in the passenger side front seat cushion squib circuit, Faulty seat cushion squib, Corrosion or loose connections in the circuit.

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.

• Description
• Common Causes
• Symptoms
• How To Fix
• Cost to Fix
• FAQs
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Common Causes of B1878

Symptoms of B1878

How to Fix B1878

Cost to Fix B1878

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Code B1878 Information for Specific Makes

• B1878 Ford — Seat Belt Driver Pretensioner Circuit Short To Battery
• B1878 Lexus — Short to Positive in Passenger Side Front Seat Cushion Squib Circuit
• B1878 Lincoln — Seat Belt Driver Pretensioner Circuit Short To Battery
• B1878 Mazda — Seat Belt Driver Pretensioner Circuit Short To Battery
• B1878 Mercury — Seat Belt Driver Pretensioner Circuit Short To Battery
• B1878 Scion — Short to Positive in Passenger Side Front Seat Cushion Squib Circuit
• B1878 Toyota — Short to Positive in Passenger Side Front Seat Cushion Squib Circuit

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 B1878 Code

1. What are the common symptoms of OBDII code B1878 (Short to Positive in Passenger Side Front Seat Cushion Squib Circuit)?

The common symptoms of this code may include an illuminated airbag warning light on the dashboard and potential non-deployment of the passenger side airbag in the event of a collision.

2. What are the possible causes of OBDII code B1878?

Possible causes of this code include a short circuit to the positive terminal in the passenger side front seat cushion squib circuit, faulty wiring, or a malfunctioning airbag control module.

3. How can I diagnose OBDII code B1878?

Diagnosing this code typically involves using a diagnostic scan tool to retrieve the specific fault code, visually inspecting the wiring and connectors in the passenger side front seat area, and performing continuity and resistance tests on the circuit.

4. Can I continue driving with OBDII code B1878 present?

It is not recommended to drive with this code present, as it signifies a potential issue with the passenger side airbag system, which could compromise occupant safety in the event of an accident.

5. How can OBDII code B1878 be repaired?

Repairing this code usually involves identifying and repairing the short circuit to the positive terminal in the passenger side front seat cushion squib circuit, repairing or replacing any damaged wiring, and resetting the airbag system.

6. Is it safe to attempt to repair OBDII code B1878 myself?

Due to the safety implications of airbag system malfunctions, it is recommended to have this code diagnosed and repaired by a qualified automotive technician to ensure the work is done correctly and safely.

7. How much does it typically cost to repair OBDII code B1878?

The cost of repairing this code can vary depending on the specific cause of the issue, the extent of the damage, and the labor rates in your area. It is advisable to obtain estimates from local repair shops.

8. Can OBDII code B1878 be intermittent?

Yes, this code can sometimes be intermittent if the short circuit in the passenger side front seat cushion squib circuit is sporadic. However, it is essential to address the issue promptly to ensure proper airbag functionality.

9. Will OBDII code B1878 reset on its own?

If the underlying issue causing the code is not resolved, it is unlikely to reset on its own. Even if the warning light goes off temporarily, the code may reappear if the fault is not fixed.

10. How long does it take to repair OBDII code B1878?

The repair time for this code can vary depending on the complexity of the issue and the availability of parts. In some cases, the repair may be completed within a few hours, while more involved repairs could take longer.