The control module detected that the signal in the Internal Mode Switch 'S' circuit stayed below the expected operating range. This is the manufacturer-specific definition used by Chevrolet.
TuningBot DTC Database · v4.37.15
P1840 Diagnostic Trouble Code (2 interpretations)
2 manufacturer-specific interpretations across 2 manufacturers in the TuningBot DTC database.
Chevrolet
1 interpretation
Ford
1 interpretationThe control module detected a short circuit to battery voltage in the Transmission Transfer Case Shift Motor circuit. This is the manufacturer-specific definition used by Ford.
Related and nearby codes
How to read P1840
Powertrain: engine, transmission and driveline systems.
Manufacturer-defined range: the meaning can differ between brands.
Specific fault index within the subsystem.
Frequently asked questions about P1840
What does P1840 mean?
Diagnostic Trouble Code (2 interpretations). The control module detected that the signal in the Internal Mode Switch 'S' circuit stayed below the expected operating range. This is the manufacturer-specific definition used by Chevrolet.
Is P1840 generic or manufacturer-specific?
P1840 is a manufacturer-specific code. In this database it is documented for: Chevrolet, Ford. The same number can mean something different on other brands.
Can TuningBot remove P1840 at file level?
If the fault logic lives in the ECU calibration, yes: our DTC Removal file service disables the specific fault entry. Checksum correction is not included: it is a separate, optional service. Not sure whether your case qualifies? Request a free assessment and our engineers will check your ECU file.
Other file services
Understand the system behind this code: Diagnostic Strategy and DTC Logic
