Conditions For Setting DTC P1860

WARNING: This page is about a different car, the 2002 GMC Yukon XL, 2002 GMC Sierra, 2002 Chevrolet Suburban, and 2002 Chevrolet Silverado. However, it is still accessible from the selected car via links, so may be relevant.

DTC will set if all conditions for running the DTC are met, and either of the following conditions occur for 4.3 out of 5 seconds.

The PCM commands the TCC PWM solenoid valve off (zero percent) and the voltage input remains low (zero volts).
The PCM commands the TCC PWM solenoid valve on (100 percent) and the voltage input remains high (battery voltage).