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P0499 code help

DenaliX

By DenaliX
in Troubleshooting & Recalls

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DenaliX Enthusiast

DenaliX

Posted
Posted

I have a 2017 crew cab. I have replaced the evap solenoid and canister but the code will not go away. Can it be a wiring issue? What exactly would I need to get to replace the wiring if it is that?

carnau Enthusiast

carnau

Posted
Posted
42 minutes ago, DenaliX said:

I have a 2017 crew cab. I have replaced the evap solenoid and canister but the code will not go away. Can it be a wiring issue? What exactly would I need to get to replace the wiring if it is that?

Ok. Lets talk about this before we throw any more parts at it. Why you put a canister on it for a Vent control circuit code is already a mystery. If you want to throw money away I will give you my paypal! LOL

 

Ok, So the P0449 is a Vent Solenoid Valve Control Circuit code.

 

What this means is the ECM sees that the vent control circuit is open.

 

Lucky for you this is a SIMPLE circuit.

 

There are 2 wires coming to the vent solenoid.

You have a Red/Green wire. This wire should have power on it... ALL THE TIME. It is Powered by fuse 67 at the underhood fuse block. Go ahead and give that a check and make sure the fuse is good.

Once you have tested it and made sure the fuse is good, Disconnect the vent valve itself and test the red/green wire WITHOUT cramming your test-light in the terminal and screwing it up. Just a little touch will suffice.. just the tip... lol. If your test light shines bright like a diamond... That circuit is good.

 

Next we go to the Control circuit. The control circuit for 99% of everything GM is a ground circuit. In order to test this circuit you really need to have access to a inexpensive scanner that will control the solenoid open and closed...  and for only 34.98 + the coupon that Amazon gives you saving you an extra 10% you can have this ( https://amzn.to/3a7OWcx ) practically basic paperweight scanner that will command your vent solenoid open and closed, clear codes, and illuminate your vehicle on a dark stormy night just long enough to kill your battery and leave you stranded on the side of the road.

 

If you decide to purchase this gem, while the vehicle is in the run position. Command the circuit on and off and using your test light like a precision penile enlargement surgeon, insert just the tippy tip ohh so softly in the end of terminal 1 White with the other end connected to power, and see if the test light flashes like the lights of a Christmas tree.

 

Now, if you are broke or like me so tight with your money, you squeak when you walk (tight butt cheeks joke... I workout.) We can test the circuit the hard way.

 

To do this you need to disconnect connector 1 of your engine control module. with a piece of 18 gauge wire, strip the end of it and twist the wires tighter than... well my butt cheeks again and insert it (just the tip) into terminal 56 White wire of connector 1. With other end of your extremely long 18 gauge wire... stretch it across the engine and attach it to the positive post of your battery. What this will do is send power down that circuit and you can test the continuity and the amount of amperage that wire will allow by testing it at terminal 1 White wire of at the vent solenoid. If it lights up your test light... Then that circuit is good as well. 

 

At this point if both circuits test good. You either have a faulty part... again... or a faulty ECM.

 

All joking aside... this is an easy test... stop throwing money away. 

Love you, Mean it!

 

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DenaliX Enthusiast

DenaliX

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Posted

I was just going through the steps I found on google lol. I will give this a try!! Thank you so very much for all the information! I really appreciate it. Love you man ❤️ 

  • 4 years later...
newdude Senior Enthusiast

newdude

Posted
Posted
4 hours ago, Leftside said:

How did this work for you I’m having similar issues replaced both parts as well and still have a check engine light coming back on.

 

 

EVAP smoke test and find the leak.  Stop shotgunning parts at it.  

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