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P1847

2 3 Shift Solenoid Circuit High Voltage.

  • GMC
  • Powertrain
  • Manufacturer code
  • Medium severity

How this code is built

P
SystemPowertrain
1
Defined byThe manufacturer
8
AreaTransmission
47
FaultThe specific fault in that area

What it means

P1847 on a GMC means the transmission control module has detected a high voltage condition in the 2-3 shift solenoid circuit. The module monitors the solenoid control circuit and sets the code when the voltage it sees does not match what it is commanding, which points to an open circuit, a short to voltage, or a faulty solenoid or driver. The exact solenoid layout and wiring depend on the model and transmission fitted.

Symptoms

  • Harsh, delayed or missed 2-3 upshift
  • Transmission stuck in one gear or in a limp-home mode
  • Gearbox warning light or check engine light on
  • Flared revs or slipping between second and third
  • Poor fuel economy or sluggish acceleration

Possible causes

  • Faulty 2-3 shift solenoid (open circuit or internal fault)likely
  • Damaged, chafed or corroded wiring between the solenoid and the transmission control modulelikely
  • Poor connection at the transmission internal harness connector or pass-through connector, including contamination by fluidlikely
  • Wiring shorted to a voltage supplypossible
  • Low or contaminated transmission fluid affecting the solenoid or the wiring inside the unitpossible
  • Faulty transmission control module or its solenoid driverrare

How to diagnose

  1. Read all stored codes and freeze frame data, noting when the fault set and whether other transmission codes are present
  2. Check transmission fluid level, condition and smell, and look for debris or burnt fluid
  3. Inspect the wiring and connectors from the transmission to the control module for chafing, corrosion, bent pins and fluid ingress
  4. Check the battery and charging voltage, since low or unstable supply can upset circuit monitoring
  5. Measure the solenoid resistance at the connector and compare with the manufacturer specification for that transmission
  6. Check the solenoid control circuit for a short to voltage or an open circuit, using the wiring diagram for the model
  7. Command the solenoid with a suitable scan tool function, if supported, and watch the response and circuit voltage
  8. Only after wiring and solenoid are proven good, check the control module for faults and any applicable calibration updates

How to fix

  • Replace the 2-3 shift solenoid if it is out of specification, following the procedure for that transmission
  • Repair or replace damaged wiring and corroded or loose connectors
  • Replace the internal harness or pass-through connector if it is contaminated or faulty
  • Correct the fluid level or service the transmission with the specified fluid if it is contaminated
  • Repair or replace the transmission control module if it is confirmed faulty, with programming as required

Can I keep driving?

Medium severity

The car can usually be driven a short distance, but the transmission may be in limp mode and shifting will be poor. Get it checked soon, as continued driving with incorrect shifts can cause extra wear or damage to the transmission.

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

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