93 chevy C1500 5.7L EGR Solenoid Test

[ollie57]

Hello, folks I am looking for some input, Im not getting 12v across the EGR solenoid leads, I get 12v when I touch the probe to Blk/Pink and ground. Wondering what would be the next step in trouble shooting. Also the serv eng light comes on intermittently after engine warms but will reset itself. pulled a code of 33. thanks

[dave w]

Most of us usually delete the EGR in the PROM.

It seems to me the problem is related to the EGR solenoid. The PCM turns On / Off the EGR solenoid. I would use a hand vacuum pump to see if I could manually activate the EGR solenoid. I would unplug the solenoid and briefly apply battery + / - to EGR solenoid to see if it cycles, 15Hg on the vacuum pump goes to ZERO. Maybe the EGR solenoid will not hold 15 Hg of Vacuum with the solenoid unplugged?

dave w

[billygraves]

Hello, folks I am looking for some input, Im not getting 12v across the EGR solenoid leads, I get 12v when I touch the probe to Blk/Pink and ground. Wondering what would be the next step in trouble shooting. Also the serv eng light comes on intermittently after engine warms but will reset itself. pulled a code of 33. thanks

The EGR Diag Code is dependent on which system or year you have. Some car ECM use the EGR control line to see if it has 12 v with EGR Off and 0 volts when commanded On. Other systems (some truck and cars) use the O2 measurement to tell if the EGR has activated. (A sluggish O2 will set EGR code and not the O2.)

I've seen a few where the Transmission TCC Solenoid has very low resistance causing an EGR diag Code to set at times. The TCC Sol measured about 15 ohms at 70 deg F. (The EGR and TCC sol share the same QUAD driver)

[ollie57]

Thanks for your advise I checked all settings as recommended, no faults discovered. All tested good. I also used a better test light which now reflects the 12v as service tech note states across terminals, also checked for vacuum leaks with negative findings. So on to the next items MAP sensor, temp, etc.... Will keep posted of my findings.