Black smoke was EGR now SES light

[DILLIGAFRI]

All the black smoke turned out to be the EGR valve. Pluged the hose and the smoke stoped but I got an SES light the next day from the egr Any ideas on how to get the lite to stay out

[freddys]

If you truck has a L56 motor, you will have to change the ECM to a L65 ECM or get your ECM reprogramed. This is the only way you will get it to work without the light coming on.

freddy

[Polar Diesel]

or just fix what was initially wrong with the egr.

[DILLIGAFRI]

Fixing the EGR was the original idea. Valve seems to work OK but am wondering if there is a leak in the diaframe of the valve that is killing the vaccuum to the boost. More testing tonight. What is sensing that the EGR is not working. Vacuum hose is pluged not control disconected.

[Polar Diesel]

i'm not sure what senses when egr isn't hooked up.some kind of vac. switch?

[JohnC]

Originally posted by DILLIGAFRI:
What is sensing that the EGR is not working.If it's an earlier model the pressure sensor on the firewall senses vacuum control pressure in the line going to the EGR valve. To get around it, simply plug the line after the tap to the sensor. If it's a later model the mass air flow sensor detects no EGR. No easy way around it.

To test the diaphragm, suck on the line to the EGR valve and then plug it with your tongue. If it holds vacuum, the diaphragm is ok. If it looses vacuum it's perforated.