Quote:
Originally Posted by Stringer
Thanks for the diagram. I bought a shop manual but your pic is easier to read. Thought I had it taken care of but I'm having trouble getting air to blow out of the defrost (I posted another question about that) and, even though I replaced it, I'm still getting an intermittent code for EGR. Only happens sometimes after driving at highway speeds for a while.
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The EGR code is one one of the most annoying SES codes to get rid off. 1st off disconnecting will not fix it -so forget about that approach. The way ECM checks for EGR functionality is when operational conditions are:
-Throttle position (TPS) is between 10% and 25%
-Steady throttle with no more then 2% change in throttle position.
-Vehicle speed is above 32 MPH
-ECM in closed loop operation
-Max short term fuel trim less then 6 counts for 3.2 seconds
-desired EGR command greater then 40% duty factor
-MAP above 47.5 kPa or less then 15 kPa.
Basically the ECM cuts the EGR OFF and expects to see a predetermined outcome. After failing the test twice a code 32 will be set. Usual suspects are:
1) Wiring harness - disconnected, damaged, etc
2) EGR solenoid - broken or disconnected vacuum lines.
3) EGR diaphragm is defective ( very common)
4) Intake manifold EGR passages are clogged with oil and carbon deposits (common in high millage engines)
Do you have AC or heater only in your burban??
//RF