OBD-II Code
B2740
Severity
Not yet reviewed
Nobody on our side has assessed this code yet, so we are not going to guess at how serious it is.
Can you drive it
We cannot say
Treat it as unknown until a shop reads it with live data. If the check-engine light is FLASHING, stop driving as soon as it is safe to — that means an active misfire, whatever the code.
Indicative cost (USD)
$40–$550
From this code's diagnostic notes. Varies by vehicle, diagnosis, parts, and local labor. This is not a repair quote.
$40 (aftermarket switch DIY) to $550 (OEM switch plus door-jamb wiring repair on a truck).
B2740 is a door-lock switch circuit fault — the BCM is reading an invalid voltage state on one of the lock/unlock switch inputs (typically the driver-door master switch).
How a shop works this
Work from evidence to part, not the other way round. A code names a circuit or a symptom; it does not name the part that failed.
Note every code that is set, not just this one.
Codes that appear together usually narrow the cause faster than any one of them read alone.
Read the freeze frame — the conditions the fault was recorded under.
Cold or warm, idle or load, road speed and engine speed. A fault that only appears cold is a different fault from one that only appears under load, even with the same code on the scanner.
Confirm the fault is current rather than history.
Clear the code and see whether it returns under those same conditions. A code that does not come back may have been logged during a repair, a flat battery, or a bad connection that has since been disturbed.
Then follow the diagnostic notes further down this page, in the order they are written.
They are written in the order a shop works this code, cheapest checks first. Where they name a component, inspect its wiring and connector before replacing it.
If the code comes back after a repair, the underlying fault is still there. That is the point to bring in a scanner with live data and freeze-frame, or a shop that has one.
Common symptoms
- Check engine light
Read the full diagnostic procedureB2740 is a door-lock switch circuit fault — the BCM is reading an invalid voltage state on one of the lock/unlock switch inputs (typically the driver…
B2740 is a door-lock switch circuit fault — the BCM is reading an invalid voltage state on one of the lock/unlock switch inputs (typically the driver-door master switch). A properly functioning door-lock switch reads ~5V at rest (pulled up internally by the BCM) and drops to 0V when pressed; B2740 sets when the input is stuck low (shorted to ground), stuck high beyond the pull-up reference, or chattering.
Cheapest-first ladder
- Operate every lock/unlock button on every door switch while watching the BCM's switch-state PIDs live — a switch that doesn't toggle the BCM's input has either a broken switch contact, a broken wire in the door-jamb boot, or a chafed wire shorted to ground inside the door.
- Pull the driver-door master switch (usually 2-4 screws and one connector) and bench-test each switch position with a multimeter — should show ~0 ohms pressed, infinite at rest.
- Inspect the door-jamb wire boot — this is where 80% of door switch wiring failures happen, especially on trucks where the door cycles a million-plus times over a decade. Look for green corrosion, broken strands, and chafed insulation.
- Replace the door master switch ($40-$150 aftermarket, $150-$400 OEM) only after confirming the wiring is good. Expensive-misdiagnosis caveat: a chafed wire in the door-jamb boot mimics a bad switch perfectly — replacing the switch without fixing the wire just sets the same code in 50 miles.
Vehicle-specific patterns2007-2014 Chevrolet Silverado, GMC Sierra, Tahoe, Yukon, Suburban driver-door master switch is the canonical B2740 — the switch's internal contacts w…
- 2007-2014Chevrolet Silverado, GMC Sierra, Tahoe, Yukon, Suburban driver-door master switch is the canonical B2740 — the switch's internal contacts wear out from a decade of daily use, and GM replacement switches from the dealer are $200-$400 while aftermarket Dorman units are $40-$80 and last about as long as the original.
- 2009-2014Ford F-150 driver-door master switch throws B2740 from the same wear pattern, and additionally from a documented door-jamb wire chafe at the upper hinge boot — fix the wire, not the switch.
- 2008-2013Cadillac CTS and 2010-2015 GM full-size SUVs throw B2740 from water intrusion into the door-mounted switch assembly when the door's outer weatherstrip degrades — drying and contact-cleaning the switch sometimes recovers it.
- 2003-2008Honda Pilot/Odyssey throws B2740 from a known driver-door master-switch board solder-crack issue, with aftermarket reman boards available for $30.
Estimated repair$40 (aftermarket switch DIY) to $550 (OEM switch plus door-jamb wiring repair on a truck).
Look up another code
More free tools