DTC 71 - Set/Coast Switch Fault: Notes

WARNING: This page does not describe the selected car, but rather 10 other vehicles, including the 1994 GMC Yukon, 1994 GMC Suburban, 1994 GMC Pickup, 1994 GMC Cab & Chassis, and 1994 GMC C3500 HD. However, it is still accessible from the selected car via links, so may be relevant.

The cruise ON/OFF, SET/COAST and RESUME/ACCEL switches are inputs to the fuel control portion of the PCM. These inputs allow the PCM to control and hold a requested speed. The set/coast request signal circuit supplies ignition voltage to the PCM when set/coast is depressed. DTC 71 will set when:

Cruise control is on.
Ignition voltage on the set/coast request signal circuit is present for more than 20 seconds.

PCM will default to the PCM disallowing all cruise inputs. TCC shift schedules may be affected.

NOTE: Test numbers refer to numbers on diagnostic chart.

This step determines if the cruise control switch is okay.
This step determines if the PCM or switch is at fault.