B1994 code definition

A B1994 trouble code is stored by the Powertrain Control Module (PCM) if a problem is detected with the driver's side side-mount air bag circuit. Usually, this is in the form of a variance of the voltage signal received by the PCM from the driver's side side-mount air bag circuit that falls outside of the specifications set by the manufacturer. Additional codes that a mechanic might find stored alongside a B1994 trouble code include a B1992, B1993, B1995, B1996, B1997, B1998, and B1999 code.

What the B1994 code means

When the voltage signal sent from the driver's side, side-mount air bag circuit falls outside the specified levels set by the vehicle manufacturer, a B1994 trouble code is stored and the SRS warning light illuminates. Many vehicle also disable the SRS system until the issue is fixed and the trouble code cleared, so it is important to get a B1994 trouble code looked at as soon as possible.

What causes the B1994 code?

Common causes of a B1994 trouble code include loose, faulty, or otherwise damaged wiring, connectors, and other components. Other causes of this trouble code include loose or corroded battery cable connectors, a bad battery, and faulty air bag components and a problem with the ground wire.

What are the symptoms of the B1994 code?

The PCM signals the storage of a B1994 trouble code by illuminating the SRS warning light. In the case of a failure on the part of the SRS warning light, the PCM signals the driver of such failure with a series of audible tones while the vehicle is in operation.

How does a mechanic diagnose the B1994 code?

Properly diagnosing a B1994 trouble code requires the mechanic to use an advanced scanner and a digital volt/ohm meter with the output set at 10 mA or less to avoid setting off the air bag mechanism. In addition, the mechanic should take the following steps:

  • The mechanic should begin the diagnostic by clearing the trouble code and testing the system to see if the code returns.

  • If the B1994 trouble code returns, download any stored trouble codes and the freeze frame data from the PCM using the advanced scanner.

  • Start the vehicle and test the wiring harness for the driver's side, side mounted air bag to see if it has any loose wiring or connections.

  • The mechanic should also perform a test drive while the vehicle is running to see if the code is stored again.

  • If the code returns, the mechanic should first disconnect the battery cables and give the wiring harness a more thorough inspection.

  • In addition, while the battery is disconnected, the mechanic should check the battery cable clamps for corrosion.

  • After reconnecting the battery cables, reprogram the air bag control module, if needed, and clear the code.

  • If the code returns, test the reference voltage and ground signal at the driver's side, side mount air bag circuit using the digital volt/ohm meter.

  • If the mechanic cannot detect a signal, they should disconnect the PCM and all related control modules and then test the continuity of the driver's side, side mount air bag circuit with the battery ground.

  • In addition, the mechanic should check the continuity between the air bag control module and the PCM using the digital volt/ohm meter.

  • Clear the B1994 trouble code and retest the system to see if it returns.

Common mistakes when diagnosing the B1994 code

A common mistake made by mechanics when diagnosing and repairing a B1994 trouble code is to replace more expensive components without checking the wiring or connectors for fault first. If faulty wiring or connectors are at fault in cases such as this, the problem remains and the mechanic can expect the PCM to store the code again.

How serious is the B1994 code?

While signifiers of this trouble code might seem minor, the storage of this trouble code is dangerous and possible life threatening if not fixed. Vehicle owners should have this code diagnosed and corrected as soon as possible.

What repairs can fix the B1994 code?

To successfully fix a B1994 trouble code, the mechanic must make the following repairs:

  • The mechanic should replace any faulty or damaged wiring, connectors, or components found during their diagnosis.

  • They should also make sure all wires and connectors are tightly installed.

  • Then, they should repair, clean, or replace any damaged or corroded battery cable connectors. In addition, clean the battery post of corrosion before reconnecting the battery cables.

  • If the driver's side, side mount air bag circuit is bad, replace it.

  • In addition, if the driver's side, side mount air bag is bad, replace it.

  • Replace the air bag control module if it is bad.

Additional comments for consideration regarding the B1994 code

Before inspecting the driver's side, side mount air bag, disconnect both the negative and positive battery cables. Once disconnected, the mechanic should wait at least three minutes before proceeding with the inspection to keep the air bag from possibly deploying.

Need help with a B1994 code?

YourMechanic offers certified mobile mechanics who will come to your home or office to diagnose and repair your vehicle. Get a quote and book an appointment online or speak to a service advisor at 1-800-701-6230.

This article originally appeared on YourMechanic.com as B1994 OBD-II Trouble Code: Driver Side Side-Mount Air Bag Circuit Open and was authored by Cheryl Knight.

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