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P1860

TCC PWM Solenoid Circuit Electrical.

  • Saturn
  • Powertrain
  • Manufacturer code
  • Medium severity

How this code is built

P
SystemPowertrain
1
Defined byThe manufacturer
8
AreaTransmission
60
FaultThe specific fault in that area

What it means

P1860 on a Saturn means the transmission control module has detected an electrical fault in the torque converter clutch (TCC) pulse-width modulated solenoid circuit. The module commands the solenoid and monitors the circuit, and it set the code because the current or voltage did not match what it expected, which points to an open circuit, a short or a failed solenoid. The torque converter clutch may not apply or release properly as a result.

Symptoms

  • Malfunction indicator lamp on
  • Torque converter clutch not locking up, so engine revs stay higher at cruising speed
  • Worse fuel economy on motorway runs
  • Shudder, surging or stalling when slowing to a stop if the clutch stays applied
  • Transmission running warmer than usual
  • Possible harsh or odd shifts if the module limits operation

Possible causes

  • Faulty TCC PWM solenoid (open or shorted winding)likely
  • Damaged, chafed or corroded wiring between the solenoid and the transmission control modulelikely
  • Poor connection or water or fluid ingress in the transmission internal harness or external connectorlikely
  • Contaminated or low transmission fluid affecting the solenoid and valve bodypossible
  • Low system voltage or poor earth affecting the module's circuit monitoringpossible
  • Faulty transmission control module driver circuitrare

How to diagnose

  1. Read all stored codes and freeze frame data, noting any other transmission or voltage related faults, then record and clear to see if P1860 returns
  2. Check battery condition and charging voltage, and inspect the main earths
  3. Check transmission fluid level, condition and smell, as the correct procedure and fluid type depend on the model and transmission
  4. Inspect the transmission external connector and wiring for chafing, heat damage, corrosion and fluid ingress
  5. Using the model-specific wiring diagram, test the solenoid circuit for continuity, short to earth and short to supply
  6. Measure the solenoid resistance and compare with the manufacturer specification for that transmission
  7. Use a scan tool to command the TCC solenoid and watch whether the circuit responds and the lock-up operates
  8. If wiring and solenoid test good, check the module's output and power and earth supplies before suspecting the module

How to fix

  • Replace the TCC PWM solenoid if its resistance or operation is out of specification
  • Repair or replace damaged wiring and renew corroded or faulty connectors
  • Renew the internal transmission harness or connector if it is faulty, where the model design allows
  • Correct the fluid level or change the fluid and filter if it is contaminated, using the specified type
  • Repair charging or earth faults found during the voltage checks
  • Repair or replace the transmission control module only after the circuit and supplies are proven good

Can I keep driving?

Medium severity

The car can usually be driven short distances, but without proper lock-up it will use more fuel and the transmission may run hot. Have it checked soon, and avoid heavy loads or towing until it is fixed.

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

This code for other makes

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