Thread: P0403 EGR Demon - FIXED

Tomorrow, my buddy and I will try to figure out where all the electrics are coming from that makes it poorly.

• I replaced my EGR with a known good spare. P0403 came back.
• I found a wire that touched the crossover, so I cut and spliced it up pretty yesterday. And my P0403 came back.

Can't see any other electrical problems and can't test anything without his TechII to operate the MAF.
A crazy little part of me wonders if maybe a bad MAP sensor would do it.
I've been searching my nuts off with all of the Internets and can't find what I need. What say ye?

OH. And if you tell me to "delete the EGR, bro! lolololol".... ovary punches. Ovary punches for everyone.
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FIX:
Tested all connectors at the EGR. The red power had no response. Could not get continuity from the PCM. Found the wire was shorted by the front valve cover. The short broke the EGR as well, so I replaced the EGR too.

Hmm interesting, when I googled it to find out what the code was....ahem a pet peeve of mine. I found this...

So I'll leave you with a DELETE IT!!!! and let you puss punch yourself for not listing that it's a circuit complaint.

Part 1 -GM EGR Valve Test (P0401, P0403, P0404, P0405).

Balls, that looks like some good testing right there. The only info I had was GM manual, which requires a TechII for testing. No time like the present.

Sorry to pull out the easy, quick google card on ya. Since you couldn't list the damn name....and I am bored, I figured I'd kick you in the nuts as hard as poasible.

Thanks pal. My nuts were feeling too cocky, anyway.

After reading the article:

Tests 1-3,6,7 are unnecessary, since I've determined that the EGR itself is not an issue. So, I'm going to try tests 4 and 5. Woo, less work.

Likely that's what I'd do too... Or I'd tell the code to not report and smile along my merry way.

Well, currently have a guy that stickers my car regardless... but if the light's on all the time, I'll never know if a new issue pops up. Plus, I happen to like the EGR. Chances are, if I'm not getting power/ground from the PCM, I might be having some other issue pop up in the future, too. In my experience, if a squirrel chews through one wire... they chewed at least halfway through another.

I'm grabbing my multimeter..... now.

It's my experience that if a squirrel chews your stuff up...you might be able to see it w/o a multimeter

You know what makes this fun is that you'll have it figured out in a few minutes.

You know if you removed it at the cost of some RTV and a two pennies...you wouldn't have to worry about it

Test 4: If your Multimeter displayed 4.5 to 5 Volts DC : This result let's you know that the EGR Valve's Pintle Position Sensor is getting the necessary Voltage.
Reading: 5.03V

Test 5: If your Multimeter displayed 11 to 12 Volts DC : This result let's you know that the EGR Valve's Pintle Position Sensor is being fed with a good Ground.
Reading: 12.39V

So, regardless... ground and power are present for the pintle position sensor.

Clearly...there's an issue. Both are too high.. bahahahaha

What's the next test? Or is that saying the pintle sensor is bad?

Well, I'm gonna try to test the Ground Circuit for EGR Valve Solenoid and Power Source for EGR Solenoid. Since I already tried a known good EGR...

Keep in mind that at the end of almost every diagnostic is the GM FSM.. is the last and final step of "If all else failed, shotgun a pcm at it" Might be a failed ground circuit in teh pcm.

Aaaaaahaaaaaa.

Power Source for EGR Solenoid (provided by the PCM). Red wire on the right.
Reading: Big Fat Nothing.

Wait... does the engine need to be running for that to read?

I don't think so.. Pcm should control everything via grounding...not power.

Check the pin at the pcm.

Oh good, now I need to know which pin it is at the PCM? That's like 300 wires.

I wonder if the solenoid just doesn't get power until the PCM commands it on? Or is the only thing the PCM changes the EGR Pintle Position Signal Circuit?

There's two banks of 80 possible wires, from that..about half are populated.

80+80-80=about 80. I'm an accountant..does it show?