Skip to content
GTECH Calibration
Portal

P1860

TCC PWM Solenoid Circuit Electrical/ Transmission Transfer Case Contact Plate 'D' Short Circuit To Battery.

  • Other
  • 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 is a manufacturer-specific code, so its meaning depends on the make. On Buick, Cadillac, Chevrolet, GM, GMC, Oldsmobile and Saturn it means a fault in the torque converter clutch (TCC) pulse-width-modulated solenoid circuit. The control unit saw a voltage or current on that circuit that did not match what it commanded, which points to a short or open circuit or a failed solenoid. Volkswagen uses the same number for a different fault (kick-down switch message), so confirm the make before following this guide.

Symptoms

  • Warning light on, and possibly a transmission warning or limp-mode message
  • Torque converter clutch not locking, so revs sit higher at cruising speed
  • Worse fuel economy
  • Shudder or surging at steady speed
  • Harsh or delayed gear changes
  • Gearbox running hotter than normal

Possible causes

  • Chafed, pinched or shorted wiring between the transmission connector and the control unitlikely
  • Corroded, loose or contaminated connector at the transmission or control unitlikely
  • Failed TCC PWM solenoid with an internal short or open circuitlikely
  • Damaged internal transmission wiring harnesspossible
  • Contaminated or degraded transmission fluid, or debris affecting the solenoidpossible
  • Faulty driver circuit in the transmission or powertrain control unitrare

How to diagnose

  1. Read all stored and pending codes and note the freeze frame data, including road speed, gear and fluid temperature, then check for any related transmission or electrical codes
  2. Check the transmission fluid level and condition against the manufacturer's procedure, as it varies by model
  3. Inspect the wiring and connectors from the transmission to the control unit for chafing, melted insulation, corrosion, water ingress and bent pins
  4. Check the battery and charging system voltage, as low or unstable voltage can upset solenoid circuit monitoring
  5. Measure the TCC solenoid resistance at the transmission connector and compare it with the model-specific specification
  6. Test the solenoid circuit for a short to voltage, a short to ground and an open circuit with the connector unplugged
  7. Check the commanded TCC duty cycle with a scan tool and, if needed, the PWM signal on an oscilloscope
  8. Use the model-specific wiring diagram to check the control unit output once the wiring and solenoid test good

How to fix

  • Repair or replace damaged wiring and fix any short or open circuit found
  • Clean, repair or replace corroded or damaged connectors and terminals
  • Replace the TCC PWM solenoid if its resistance or operation is out of specification
  • Replace the internal transmission harness if it is faulty, following the model-specific procedure
  • Renew the transmission fluid and filter if it is contaminated, using the specified fluid
  • Repair or replace the control unit only after the wiring and solenoid have been proven good

Can I keep driving?

Medium severity

The car can usually be driven for a short time, but book it in soon. Avoid heavy loads and towing, and stop if the gearbox overheats, shudders badly or goes into limp mode, as continued use can damage the transmission.

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

This code for other makes

Nearby codes