What are the Possible Causes of the DTC B1878 Mercury?
NOTE: The causes shown may not be a complete list of all potential problems, and it is possible that there may be other causes.
Faulty Seat Belt Driver Pretensioner
Seat Belt Driver Pretensioner harness is open or shorted
Seat Belt Driver Pretensioner circuit poor electrical connection
Faulty Restraints Control Module (RCM)
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How to Fix the DTC B1878 Mercury?
Check the 'Possible Causes' listed above. Visually inspect the related wiring harness and connectors. Check for damaged components and look for broken, bent, pushed out, or corroded connector pins.
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What is the Cost to Diagnose the Code?
Labor: 1.0
The cost to diagnose the B1878 Mercury code is 1.0 hour of labor. The diagnosis time and labor rates at auto repair shops vary depending on the location, make and model of the vehicle, and even the engine type. Most auto repair shops charge between $75 and $150 per hour.
What are Code Possible Symptoms?
Air Bag Warning Light ON
What Does the B1878 Mercury Code Mean?
The Restraints Control Module (RCM) checks all of the safety Seat Belt Pretensioners for faults. If the RCM detects a short to voltage on a Driver Safety Seat Belt Pretensioner circuit, it will store diagnostic trouble code (DTC) B1878 in memory and illuminate the air bag warning indicator.
B1878 Mercury Code - Seat Belt Driver Pretensioner Circuit Short To Battery
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.