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 Vandura Special, 1994 GMC Vandura, 1994 GMC Rally Camper Special, 1994 GMC Rally, and 1994 GMC Forward Control. 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.