DTC 44, EGR Pulse Width Error: Notes
WARNING: This page does not describe the selected car, but rather 10 other vehicles, including the 1995 GMC Yukon, 1995 GMC Suburban, 1995 GMC Pickup, 1995 GMC Cab & Chassis, and 1995 GMC C3500 HD. However, it is still accessible from the selected car via links, so may be relevant.
PCM operates the normally-open solenoid to control EGR valve. By providing a ground path, PCM energizes solenoid allowing vacuum to pass to EGR. During normal operation, PCM compares EGR duty cycle signal with EGR control pressure/BARO signal and makes adjustments in duty cycle accordingly. If there is a difference in PCM command and what is at EGR valve sensed by EGR control pressure/BARO sensor, PCM makes minor adjustments to correct. DTC 44 will set when:
- Ignition voltage is present on the EGR control circuit when EGR solenoid is commanded on.
Or
- No ignition voltage is present on EGR control circuit when EGR solenoid is commanded off.
PCM will default to shut down EGR.
NOTE:
Test numbers refer to numbers on diagnostic chart.
- This step determines if DTC 44 is result of a hard failure or an intermittent condition.
- This step checks if PCM and wiring are okay.
- This step checks voltage at EGR solenoid.