B1979 code definition
The B1979 trouble code notes a passenger seat rearward switch circuit error.
What the B1979 code means
The B1979 code is a generic OBD-II trouble code that detects a circuit malfunction in the passenger seat rearward switch. The rearward switch is usually located on the outboard side of the front passenger seat, and adjusts the seat position. When the switch is pressed, the passenger seat will move rearward to better accommodate the passenger. If the body control module or powertrain control module (PCM) note a circuit error from the passenger seat rearward switch, then the B1979 trouble code will likely be stored.
What causes the B1979 code?
There are two common causes of the B1979 trouble code. The most common cause is damaged electrical components, such as shorted wires, open or corroded connectors, and blown fuses. These damaged electrical parts can be in the passenger seat rearward switch itself, or in the power seat system. The second common cause is a failed passenger seat rearward switch. Though very rare, it is also possible for a defective body control module to trigger the B1979 code.
What are the symptoms of the B1979 code?
When the B1979 trouble code is stored, the passenger seat will likely not be able to be adjusted horizontally. The seat almost surely will not adjust rearward, and likely will not adjust forward either. The code may also be accompanied by a check engine soon warning light on the gauge cluster.
How does a mechanic diagnose the B1979 code?
The B1979 code will be diagnosed with a basic OBD-II trouble code scanner. A certified mechanic will use the scanner to view the freeze frame data and gather information about the B1979 code. The mechanic will also check to see if there are any additional trouble codes detected. If there are numerous codes present, then they should be addressed in the order in which the scanner displays them. The codes should then be reset, the vehicle restarted, and the code checked for. If it is no longer detected, then it likely represents an intermittent issue, or was triggered inaccurately.
If the B1979 code remains present, then the technician should begin by visually inspecting all of the electrical parts, and replacing any that are damaged or otherwise compromised. If the electrical components are all functional and in good shape, then it should be assumed that the passenger seat rearward switch has failed.
After the mechanic makes any repairs or replacements, the codes will be reset, the vehicle restarted, and the B1979 trouble code once again checked for. By doing this, the technician will know as soon as the issue is completely resolved.
Common mistakes when diagnosing the B1979 code
The most frequently made error when diagnosing this code comes from a failure to fully comply with the OBD-II diagnosis protocol. The protocol should always be observed, as it helps ensure that mechanics have efficient diagnoses, and accurate repairs.
It is fairly common for the passenger seat rearward switch to be erroneously condemned and replaced, because damaged electrical components were overlooked.
How serious is the B1979 code?
The B1979 trouble code will not keep a car from being drivable, or cause any drivability concerns. However, the passenger seat will likely be unable to adjust rearward or forward. If the seat is stuck too far forward, it may be impossible for a passenger to use it. If the seat is stuck too far rearward, it may be dangerous for a passenger to occupy it because of the distance from the airbag. When the B1979 code is detected, an inspection should be scheduled.
What repairs can fix the B1979 code?
Repairs for the B1979 trouble code are:
- Replacement of wires, connectors, and fuses
- Replacement of the passenger seat rearward switch
- In rare cases, replacement of the body control module
Additional comments for consideration regarding the B1979 code
This code is a manufacturer specific trouble code, which means that the definition varies from manufacturer to manufacturer. While the B1979 code signals a passenger seat rearward switch circuit issue in some cars, it may represent a different body problem for other vehicles. As is always the case, the technician should pay close attention to what vehicle is being inspected when diagnosing the B1979 trouble code.
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