P1860Manufacturer-specific code

P1860 Code: Torque Converter Clutch PWM Solenoid Electrical Circuit (GM)

On General Motors vehicles (Chevrolet, GMC, Buick, Cadillac), the P1860 code means an electrical fault in the torque converter clutch PWM solenoid circuit. The check engine light comes on. Other brands may define this number differently.

Severity
Medium
Can I keep driving?
Yes, but with caution
Estimated cost
$100 to $400
Difficulty
Medium
System
Transmission
Applies to
Depends on the manufacturer

Common in: Chevrolet

Updated Reviewed by Renzo Chacca

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What the P1860 code means

P1860 is a manufacturer-specific code: the 1 in the second position means each automaker defines what it means, not the generic SAE standard. The most widespread definition is the one used by General Motors (Chevrolet, GMC, Buick, Cadillac). If your vehicle is another brand, confirm the code text with a scan tool that supports that manufacturer.

ManufacturerMeaning of P1860
General Motors (Chevrolet, GMC, Buick, Cadillac)Torque converter clutch PWM solenoid electrical circuit

GM automatic transmissions (4L60E, 4L80E, 4T65E and others) use solenoids for shifting and for locking the converter, and they adapt clutch pressure with use.

The computer sets the P1860 code when it detects an electrical fault in the PWM solenoid that modulates converter lockup.

Before you start repairs, confirm the make, model, year and engine. With manufacturer codes, the same number can change even between engines from the same brand.

P1860 code symptoms

  • The converter does not lock up: higher fuel use on the highway.
  • Check engine light on.

Likely causes of the P1860 code

  1. Failed PWM solenoid. Confirm it with the tests in the diagnosis section.
  2. Transmission connector with oil.
  3. Wiring. Look for rubbing against the engine, the chassis or the exhaust.

How to diagnose the P1860 code step by step

  1. Measure the solenoid. It is 10 to 15 ohms.
  2. Inspect the transmission connector for oil and corrosion.

How to fix the P1860 code

  • Replace the solenoid.
  • Repair the connector.

Technical reference data

  • PWM solenoid resistance: about 10 to 15 ohms.
  • P1xxx codes are manufacturer-specific: confirm the definition with a scan tool that supports your brand.
  • Reference values: check the manufacturer data for your vehicle.

Brand-specific notes

A quick resistance check on the solenoid tells you whether the part or the wiring is to blame, which keeps you from replacing the wrong thing.

P1860 on GM

Common on GM trucks with the 4L60E transmission.

If your vehicle is another brand, check the table above for the meaning its manufacturer gives this code and confirm it with a compatible scan tool.

Frequently asked questions about P1860

What does the P1860 code mean on a GM?
It means there is an electrical fault in the torque converter clutch PWM solenoid circuit. The check engine light comes on.
Does P1860 mean the same thing on every brand?
No. It is a manufacturer-specific code, so on other brands it may not exist or may mean something different. Confirm it with a scan tool that supports your make.
Can I drive with a P1860 code?
With caution. A P1860 code means the converter may not lock up, so expect higher fuel use and some extra heat in the transmission.
How much does it cost to fix P1860?
Roughly $100 to $400 on a GM. A connector repair is at the low end, and a new solenoid with labor costs more.
Will a P1860 code clear itself?
Not while the solenoid or its wiring is faulty. After the repair, clear the code and confirm the converter locks up again.
What is the most common cause of P1860?
A failed PWM solenoid. A transmission connector with oil and damaged wiring come next.

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