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2005 Suburban Code Po449


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#1 rcthorpe

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Posted 12 December 2010 - 01:57 PM

Check engine light is currently on and it is pulling a PO449 code. I had the code cleared, and it continues to reappear. I took off (and cleaned) the EVAP vent solenoid. While the part was off the truck, I tested it with a battery, and it seems to engage/disengage when power is applied.

With the solenoid off the truck, I tested the plug with my light tester. The hot side of the plug is always hot (ignition on, truck on, truck off with the ground side of my tester attached to the truck frame). When I hook the tester (hot and ground) up to the plug I get no power (truck on, truck off, ignition on).

This being said, I don't know when the plug should actually be hot or off. Also, what should I try to check next?

Thanks

#2 8.1HD/ALLISON

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Posted 12 December 2010 - 02:54 PM

If I remember correctly the ecm ground the solenoid. Should have power at all times with key on, ground only when ecm commands it. Have you tested the evap solenoid with a Fluke DVOM( digital volt ohm meter)? Should show a resistance across the two terminals. Don't know how much but if it shows open its bad. You could also hook to a battery and apply a FUSED 12 volts and ground to see if it clicks. Sounds to me like the solenoid is at fault, which is pretty common. Good luck!

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You want fuel economy? Buy a Prius.... I have a big block!
------------------------------------------------------------------------------------------------------
2004 Chevy Silverado K2500 HD CCLB, 8.1L/Allison, 285/75R16 Goodyear Duratracs,
B&W hitch, Whelen 6 channel strobe lights, Soundoff Signal Mini Light Bar,
Dual Flowmaster Super 44's, BlackBear Tuned, Too much to list,


 


#3 rcthorpe

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Posted 12 December 2010 - 05:25 PM

I would like to think that the solenoid is the problem...easy fix.

Tested the solenoid with a battery and it "clicks" when it is given juice; which makes me think the solenoid is not the problem? Would it make a difference if it was UNFUSED?

I am also a little bewildered as to why my light tester doesn't glow when I attach it to both sides of the plug that attaches to the solenoid?

BTW, nice 8.1; I'm sure you don't lack power when you need it :thumbs:

#4 8.1HD/ALLISON

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Posted 12 December 2010 - 06:40 PM

I would like to think that the solenoid is the problem...easy fix.

Tested the solenoid with a battery and it "clicks" when it is given juice; which makes me think the solenoid is not the problem? Would it make a difference if it was UNFUSED?

I am also a little bewildered as to why my light tester doesn't glow when I attach it to both sides of the plug that attaches to the solenoid?

BTW, nice 8.1; I'm sure you don't lack power when you need it :thumbs:


Thanks! Unfused power wouldn't matter, just wanna make sure nothing gets fried :thumbs: . The test light doesn't light up when you test the two wires on the truck because the ecm controls the ground side. The solenoids are very common. I was hoping it would not click for you, but I would still bet its the solenoid. Only other things left would be the wiring or the ecm driver. Would need to have a scan tool to command solenoid on to check the driver and the ground circuit. You could try a solenoid or take it to the dealer?

backhoe6_zps0cfc8c15.jpg
You want fuel economy? Buy a Prius.... I have a big block!
------------------------------------------------------------------------------------------------------
2004 Chevy Silverado K2500 HD CCLB, 8.1L/Allison, 285/75R16 Goodyear Duratracs,
B&W hitch, Whelen 6 channel strobe lights, Soundoff Signal Mini Light Bar,
Dual Flowmaster Super 44's, BlackBear Tuned, Too much to list,


 





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