← Back to list

2000 GMC Suburban 1500 P1860 Code: Steady Service Engine Light After Clearing Codes

Model: 2000 Suburban 1500 Fault Code: P1860 Posted: 2014-11-11 15:49

I own a 2000 GMC Suburban 4WD with a 5.3L V8 engine and a 4L60E transmission. The truck drives smoothly and achieves around 14 MPG in town, but the service engine light comes on steadily—never blinking—and returns after just 5 miles of driving. Using an OBD2 scanner, I've retrieved DTC P1860 and P157. After clearing both codes, the warning light reappears within a short drive. I have already replaced the TCC PWM solenoid and the Bank 2 Sensor 2 O2 sensor, yet the issue persists. A local garage suggests replacing the torque converter and rebuilding the transmission, but since the truck performs well otherwise, I suspect a wiring or ground fault. I'm looking for expert advice on diagnosing this P1860 code specifically in my 2000 Suburban 1500 model. Thank you for any insights. Kevin

Related fault codes
P1860
Comments (2)
Anonymous 2014-11-13 14:16

This is a CIRCUIT-related issue—check if there are any other diagnostic codes present. DTC P1860 is set by the PCM when it detects a continuous open circuit, short to ground, or short to power in the TCC PWM solenoid valve circuit. The most common cause is faulty wiring or connector issues between the transmission and the PCM—especially in the transmission harness connectors. Carefully inspect the wiring from the TCC PWM solenoid to both the transmission and the vehicle's ECU.

Anonymous 2014-11-20 08:59

Thanks, kev2! I'll retrieve the wiring diagram and use my OBD2 scanner to verify continuity and check for voltage drops in the TCC PWM solenoid circuit.