Got a p0405 code along with traction control and stabilitrak codes. Bought a new EGR and replaced it. Used my obd2 scanner to reset the codes and they immediately come back when starting the car. Tried pulling fuse 33 for a minute as I read in another thread that will do the "learning/reset" for a new egr. That worked for about 20 miles and code is back again

Interesting problem with my orange wire that is supposed to be 12v. If I test it with key on and unplugged it's reads 12v. If I do nothing but plug it into egr it drops to 15mv. Grey wire seems to have good ground using meter. Wire B (tan) and D (grey) have 4.99 volts measured across them so they seem to be working. Middle brown wire has no output most likely because the orange wire loses all voltage when plugged in. Bad EGR or where should I look next?

 

try a positive battery disconnect. reconnect after 10 minutes and clear any dtc.

 

What year and engine?

 

Disconnecting the battery doesn't change anything. Its a 2007 Equinox LT with the 3.4L

 

The loss of 12V on the orange wire after plugging in the connector seems normal to me. The PCM sends 12V out to pin E (orange) OR pin A (gray) only when needed to move the pintle. Which pin is 12V and which is ground depends on if the PCM wants to open or close the pintle. The polarity between those two pins is reversed to move the pintle the opposite direction.

The pintle circuit (pins E and A) is separate from the pintle position circuit (pins B, C, and D).

You most likely have a bad EGR valve or short to ground on pin C (brown). The former seems more likely, but I'd rule out the latter first. Do this by disconnecting both the EGR valve connector and the C2 connector going to the ECM. Then, measure resistance between ground and either pin C at the EGR valve or pin 55 at the ECM C2 connector. It wouldn't hurt to also check pin B (tan wire at EGR valve connector)/pin 54 (ECM C2 connector) for a short to ground. If you see any measurable resistance, you have to find the short. If you see an open circuit on your voltmeter when testing, the wiring is good and the EGR valve is bad.

 

With both the EGR and C2 unplugged, I get infinite resistance to ground on pin C/pin55 (grey wire). Pin B/pin54 (tan wire) shows the same thing. This is by poking the wires going into the back of the c2 connector. Interestingly though if I use a paperclip in the front of the C2 connector, it shows high resistance (1.4M and 2.6M ohms) to ground on both wires. Not sure why that would happen?

What should the resistance be between pin A and E on the EGR itself? I'm getting a reading of ~6 ohms. Possibly got a bad EGR right out of the box?