P1860 on GMC
TCC PWM Solenoid Circuit Electrical
P1860 on GMC vehicles indicates tcc pwm solenoid circuit electrical. Au7o has documented this code across 1 GMC model — most commonly on Savana. P1860 is a manufacturer-specific code (most commonly seen on GM vehicles such as Chevrolet, GMC, Buick, and Cadillac) indicating an electrical fault in the Torque Converter Clutch (TCC) Pulse Width Modulation (PWM) solenoid circuit. The PCM/TCM sets this code when it detects a continuous open, short to ground, or short to power in the TCC PWM solenoid valve circuit. This solenoid controls fluid flow that locks up the torque converter, so a fault can affect shift quality, cause stalling at stops, or trigger limp mode. Typical repair costs on GMC range from $350 to $4,500, depending on the specific model and root cause.
Common Causes of P1860
- •Failed or shorted TCC PWM solenoid
- •Open, shorted, or corroded wiring in the solenoid circuit
- •Damaged or corroded transmission connector / internal wiring harness
- •Low or contaminated transmission fluid affecting solenoid operation
- •Faulty PCM/TCM or driver circuit
- •Internal transmission valve body / fluid passage problem
P1860 on GMC by Model
GMC Savana(1 issue)
- 4L80E/4L85E Harsh or Delayed Shifts, TCC Shudder and Loss of Forward/Reverse (Savana 2500/3500)1996-2009
The heavy-duty 4L80E (4L85E behind the 8.1L and the diesel) fitted to Savana 2500 and 3500 vans develops a distinct failure set from the 1500's 4L60E. Owners report shuddering around 45 mph as the torque converter clutch tries to lock, hard or late shifts, no downshift on throttle demand, and in advanced cases the van reaching operating temperature and then behaving as though it is in neutral in every gear. Root causes documented on 3500 vans include a failed TCC PWM solenoid or its electrical circuit, worn valve body bores, and pressure loss from a worn pump. Commercial-fleet duty cycles - constant loaded stop-and-go, cutaway upfit weight at the top of the GVWR - accelerate all of it.
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View P1860 across all makes →Frequently Asked Questions
What does P1860 mean on GMC?▼
P1860 stands for "TCC PWM Solenoid Circuit Electrical." P1860 is a manufacturer-specific code (most commonly seen on GM vehicles such as Chevrolet, GMC, Buick, and Cadillac) indicating an electrical fault in the Torque Converter Clutch (TCC) Pulse Width Modulation (PWM) solenoid circuit. The PCM/TCM sets this code when it detects a continuous open, short to ground, or short to power in the TCC PWM solenoid valve circuit. This solenoid controls fluid flow that locks up the torque converter, so a fault can affect shift quality, cause stalling at stops, or trigger limp mode. On GMC specifically, this code is documented across 1 model.
What causes P1860 on GMC vehicles?▼
Common causes on GMC: Failed or shorted TCC PWM solenoid, Open, shorted, or corroded wiring in the solenoid circuit, Damaged or corroded transmission connector / internal wiring harness, Low or contaminated transmission fluid affecting solenoid operation, Faulty PCM/TCM or driver circuit. Specific causes vary by model and year — see the per-model sections below.
How much does it cost to fix P1860 on a GMC?▼
Repair costs on GMC range from $350 to $4,500, depending on the specific model and root cause.
Which GMC models have P1860 documented?▼
Au7o has documented P1860 on 1 GMC model: Savana.