Code Definition

P1845 — 2-3 Shift Solenoid circuit low input

System: Powertrain  |  Type: Manufacturer-Specific  |  Make: GM

About P1845

P1845 is a manufacturer-specific powertrain diagnostic trouble code recorded for GM vehicles. It belongs to the P-prefix family of codes, which covers engine, transmission, emissions, or fuel-system faults.

When P1845 is stored, the module has detected a signal or supply voltage lower than the expected operating range.

Scanning & clearing: A generic OBD-II scan tool will usually read and clear powertrain (P) codes. For live data, freeze-frame capture, and bi-directional tests you may need a more capable scan tool that supports the vehicle's ECM protocol.

P1845 is a manufacturer-specific code. The same code string on a different make may have a different meaning. Always confirm the code's definition against the vehicle's service information for the specific make and model under test.

Code Information

This DTC sets when the Transmission Control Module (TCM) detects a low voltage condition, typically near 0V, on the 2 to 3 shift solenoid control circuit when it expects a higher voltage. This suggests the solenoid winding is shorted or the circuit is shorted to ground. The 2 to 3 shift solenoid controls fluid routing for the transition between second and third gears, and a low control circuit prevents correct actuation, which can cause harsh or incorrect shifts, failure to make the second to third shift, or a fail safe gear default. The fault is usually in the solenoid winding, its control wi...

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