Corroded, loose or damaged connector or terminals at the transmission internal harness or control module; Open or high resistance in the solenoid power supply wiring, or a chafed wire shorting to ground; Blown fuse or faulty relay supplying the transmission control circuit; Low battery voltage or poor charging system output, or poor earth connections; Faulty pressure control solenoid with internal short or high current draw; Fault inside the transmission control module or valve body wiring.

P1831

PC Solenoid Power Circuit Low Voltage.

Cadillac
Powertrain
Manufacturer code
Medium severity

How this code is built

P: SystemPowertrain
1: Defined byThe manufacturer
8: AreaTransmission
31: FaultThe specific fault in that area

What it means

P1831 on a Cadillac means the transmission control module has detected low voltage on the power supply circuit feeding the pressure control (PC) solenoid. The PC solenoid sets line pressure, so the module monitors its supply voltage and sets the code when it falls below the expected value. The cause is usually in the supply, wiring or connector rather than the solenoid itself, but this depends on the model and transmission.

Symptoms

Harsh or delayed gear shifts
Transmission stuck in one gear or in a limp-home mode
Automatic transmission warning or check engine light on
Slipping or flaring between gears
Erratic or incorrect line pressure feel
Shift quality that changes with electrical load or when hot

Possible causes

Corroded, loose or damaged connector or terminals at the transmission internal harness or control modulelikely
Open or high resistance in the solenoid power supply wiring, or a chafed wire shorting to groundlikely
Blown fuse or faulty relay supplying the transmission control circuitpossible
Low battery voltage or poor charging system output, or poor earth connectionspossible
Faulty pressure control solenoid with internal short or high current drawpossible
Fault inside the transmission control module or valve body wiringrare

How to diagnose

Read all stored codes and freeze frame data, noting any battery or charging system codes, and check for related transmission codes
Check the battery state of charge and charging system output, and inspect battery terminals and main earths
Check the fuse and relay for the transmission control supply using the wiring diagram for the specific model
Inspect the wiring and connectors between the control module and transmission for chafing, corrosion, water ingress and pin tension
Measure the supply voltage at the PC solenoid connector with the ignition on and while the engine runs, and check for voltage drop under load
Check the wiring for continuity and for shorts to ground with the battery disconnected, following the model wiring diagram
Test the solenoid resistance against the manufacturer specification, as the procedure and values vary by transmission
Check the transmission fluid level and condition, as contamination can affect the internal harness and solenoids

How to fix

Clean, repair or replace corroded or damaged connectors and terminals
Repair or replace open, high resistance or shorted supply wiring
Replace a blown fuse only after finding the cause of the overload, or replace a faulty relay
Restore the battery and charging system to good condition and repair poor earth connections
Replace a faulty pressure control solenoid or internal harness, then correct the fluid level or condition if needed
Check for a manufacturer software update and apply it only if the module is confirmed faulty or outdated

Can I keep driving?

Medium severity

The car may be driven carefully for a short time, but incorrect line pressure can cause slipping and wear the clutches, so get it checked soon. If the gearbox is in limp mode or slipping badly, limit driving.

Guide written by AI from the code's definition. Confirm with a diagnosis before replacing parts.