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B1985 OBD-II Trouble Code: Seat Switch Lumbar Deflate Circuit Failure

diagnostic check engine light

B1985 code definition

A B1985 trouble code denotes that the Engine Control Unit (ECU) of the given vehicle has registered an unspecified failure relating to the seat switch lumbar deflate circuit.

What the B1985 code means

The lumbar circuits are so-named for relating to the lower region of the back. In certain luxury models of vehicle (such as the Lincoln town car) the lumbar controls will allow you to sculpt the back support of the seat to enable better comfort. In the case of a B1985 trouble code, the circuit controlling the deflation of the lumbar cushion has suffered an unspecified failure.

What causes the B1985 code?

A B1985 is likely caused by faulty circuitry. In some instances, the ECU may be reporting the B1985 code falsely. If this is proven to be the case, the ECU may require reprogramming or replacement. Although this cause is quite rare, it may be considered once all circuit-related causes have been exhausted.

What are the symptoms of the B1985 code?

You will be unable to deflate (or soften) the lumbar cushion while a B1985 code is in effect. In addition, the B1985 code will result in an illuminated check engine lamp, as well as a stored trouble code. These symptoms are present for a diagnostic sake, and can be ignored once you've ascertained what the vehicle's problem is.

How does a mechanic diagnose the B1985 code?

The B1985 trouble code may be first identified by hooking up an OBD-II code reader to the ECU and scanning for stored codes. The lumbar controls are usually found at the lower side of the seat, and the circuitry is located underneath the seat. Any wiring related to the deflate circuit is suspect to have potentially caused this issue, and should be inspected thoroughly for signs of damage, disconnection, corrosion, or faultiness.

Common mistakes when diagnosing the B1985 code

Body-related trouble codes can describe different issues depending on the make and model of vehicle in question. Make sure you are addressing the right description before you commit to repairs. Misinterpreting a code's meaning can result in investing in unnecessary repairs, all the while leaving the real problem unaddressed. Modern OBD-II code readers should be able to read the specific description for you. If you're unsure about the code description, refer to the vehicle's user manual, or contact the manufacturer.

How serious is the B1985 code?

The lumbar cushion is a luxury by design. Its purpose is purely for additional comfort. As such, it shouldn't be considered a serious issue, and may only be caused for concern if the lumbar cushion is so inflated that it causes you discomfort while operating the vehicle.

What repairs can fix the B1985 code?

The wiring (along with any problematic connectors) should be rewired, repaired, or even replaced depending on the severity of the noted wiring issue. In the rare case that the ECU is faulty, it may need to be reprogrammed or replaced instead of the deflate circuit components. After you've completed your repairs for the B1985 trouble code, you should restart the vehicle. This will give the trouble code a chance to recur if it hasn't been properly addressed already.

Additional comments for consideration regarding the B1985 code

Other lumbar cushion-related codes may accompany a B1985. You can purchase an independent lumbar cushion if you'd like to retain the lumbar support without making the repairs.

Need help with a B1985 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.

The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details
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