Powertrain Controls - ECM/PCM

DTC 44 EGR Pulse Width Error:

EGR Pulse Width Error:

***This article was updated by TSB No. 51-65-73***

CIRCUIT DESCRIPTION
The Powertrain Control Module (PCM) operates a solenoid to control the Exhaust Gas Recirculation (EGR) valve. This solenoid is normally open. By providing a ground path the PCM energizes the solenoid which then allows vacuum to pass to the EGR.

During normal operation, the PCM compares its EGR duty cycle signal with the EGR control pressure/Barometric Absolute Pressure (BARO) signal and makes corrections in the duty cycle accordingly. If there is a difference in the PCM command and what is at the EGR valve sensed by the EGR control pressure/BARO, the PCM makes minor adjustments to correct.

DIAGNOSTIC TROUBLE CODE (DTC) 44 WILL SET WHEN
Ignition voltage on CKT 435 when PCM is requesting EGR solenoid "ON."
OR
No ignition voltage on CKT 435 when PCM is requesting EGR solenoid "OFF."

ACTION TAKEN (PCM will default to)
The PCM will shut down the EGR.

DTC 44 WILL CLEAR WHEN
The fault condition(s) no longer exist, and the ignition switch is cycled "OFF" then "ON."

DTC CHART TEST DESCRIPTION
Number(s) below refer to circled number(s) on the diagnostic chart.
1. This step determines if DTC 44 is a hard failure or an intermittent.
2. This step checks to see if PCM and wiring are OK.
3. This step checks voltage at the EGR solenoid.

DIAGNOSTIC AIDS
An open in CKTs 439 or 435 will cause a DTC 44 to set.