Reflash PCM

[AnalogVX]

I have a couple trouble codes relating to the EGR and 02 sensors.I have had the EGR valve replace a couple years ago and the tube cleaned recently. My shop did some troubleshooting and are thinking its more than codes and that I need to reflash the PCM. Unfortunately, they cannot do it. Anybody have a similar situation?

[simonsayz1]

Biggers Chevrolet in Elgin used to be an Isuzu dealer I believe. Might give them a call and see if they can do it.

[AnalogVX]

Thanks Simon. I called and they say they may be able to do it if they have the correct software. But they will have to hook up to check. In the meantime I got more info from the Tech that worked on it and it's the infamous P0405 code. He claims that the PCM isn't supplying enough voltage to operate the EGR. Lucky for me, the search function came back with tons of things to try before I go to Biggers Chevy.

[simonsayz1]

Good luck. There are more ex-Isuzu dealers in Chicagoland area but I figured that was the closest to you.

[AnalogVX]

Well, I found voltage to the EGR.
Black w/yellow trace 12V
Red 5V
Yellow w/ Red trace 44mv
Green 35mv
Yellow 11V

Would anyone know if these are normal? According to OBD Codes online, I should have 12V and 5V respectively, but has nothing about the others. I would like to not have the ECM flashed as suggested. I will take off the EGR valve and check for carbon build up while I'm here. With all the faulty replacement EGR valve threads, Im kind of leaning to that end.

[Cobrajet]

Well, I found voltage to the EGR.
Black w/yellow trace 12V
Red 5V
Yellow w/ Red trace 44mv
Green 35mv
Yellow 11V

Would anyone know if these are normal? According to OBD Codes online, I should have 12V and 5V respectively, but has nothing about the others. I would like to not have the ECM flashed as suggested. I will take off the EGR valve and check for carbon build up while I'm here. With all the faulty replacement EGR valve threads, Im kind of leaning to that end.

I've had a recurring P0405 issue also. I am on my 4th EGR valve. I've had three NAPA EGR valves (two replacements under warranty), and am currently running the generic $45 eBay valve with no codes since installation. I wouldn't blame the ECU so fast. These EGR valves are finicky.

I posted an excerpt from the All-Data EGR test procedures a few months back. You might give that a shot.

[AnalogVX]

Thanks CobraJet. I found that website too, but none of my wires are labeled A,B,C or D. I went thru process of elimination to figure out which was which and I believe I probed the right ones. I did find the pintle was sticking when I tried to measure resistance at the yellow/red wire, so I freed it up and cleaned it with Deep Creep. The exhaust tube is blowing and the intake is sucking, so I don't think anything is clogged. I still have the CEL. I am going to have it scanned when Advance Auto opens this morning to see where I stand.

[AnalogVX]

For future searches, here is a link to the procedures I followed.
http://easyautodiagnostics.com/gm/4....-valve-tests-1

[simonsayz1]

Analog,
Harbor Freight has some inexpensive scanners. I have the Centech deluxe. It's $79 and if you pick up a flyer in the store there's usually a 20% of coupon for any one item in the store. Let's you scan and erase codes. Plus other stuff that's over my head.

[Y33TREKker]

Well, I found voltage to the EGR.
Black w/yellow trace 12V
Red 5V
Yellow w/ Red trace 44mv
Green 35mv
Yellow 11V

Would anyone know if these are normal? According to OBD Codes online, I should have 12V and 5V respectively, but has nothing about the others. I would like to not have the ECM flashed as suggested. I will take off the EGR valve and check for carbon build up while I'm here. With all the faulty replacement EGR valve threads, Im kind of leaning to that end.

Based on the circuit diagram from the "DTP P0405 EGR Low Voltage" section of the downloadable VX service manual, those readings appear as if they'd be what a person would normally expect to me anyway.

Have you traced the wiring harness back to other connections and either just disconnected and reseated, or disconnected, cleaned, added waterproofing dielectric grease and reseated them? I've had water get into connectors before and had the VX go crazy, and if it can happen to one connector, it can happen to others.