The purge valve is on the top of the intake but it will not fix it. If you replace the vent valve most likely it will fix it. If I remember correctly if you let down the spare tire you should see it. The is a TSB on relocating the vent valve not the purge valve.
Bulletin No.: 04-06-04-055A
Date: March 20, 2006
LR4, LM4, LM7, L59, LQ9, LQ4, L18 DTC P0446 (Restricted/Blocked EVAP Vent Path) Set, Service Engine Soon (SES) Lamp Illuminated (Replace Vent Solenoid and Bracket)
2000-2003 Cadillac Escalade
2002-2003 Cadillac Escalade EXT
2003 Cadillac Escalade ESV
2000-2003 Chevrolet Suburban, Tahoe
2002-2003 Chevrolet Avalanche
2000-2003 GMC Yukon, Yukon XL
with 4.8L, 5.3L, 6.0L, 8.1L Vortec(TM) V8 Engine (VINs V, P, T, Z, N, U, G - RPOs LR4, LM4, LM7, L59, LQ9, LQ4, L18)
This bulletin is being revised to add updated warranty information and enhance the content. Please discard Corporate Bulletin Number 04-06-04-055 (Section 06 - Engine/Propulsion System).
Some customers whose vehicles are operated in dusty type environments, such as farming or mining off-road type applications, may comment about the illumination of the instrument panel SES light, with a DTC of P0446 (Restricted/Blocked EVAP Vent Path) being set.
Dirt and dust intrusion into the EVAP canister vent solenoid, resulting in restricted air flow, may cause this condition.
After following the Service Manual diagnostic P0446 and determining that the EVAP canister vent valve is the cause of the SES light, replace the existing EVAP canister vent solenoid and bracket. This new vent solenoid has an enhanced filtering capability and a filter element that can be easily removed and cleaned. To ensure correct installation, follow the procedure below.
1. Raise and suitably support the vehicle. Refer to Lifting and Jacking the Vehicle in General Information.
2. Remove the bolt retaining the vent valve bracket.
3. Disconnect the electrical connector.
4. Disconnect the canister vent valve hose.
5. Install the new vent valve bracket, P/N 15105605, to the vehicle with the retaining bolt.
Tighten the bracket mounting bolt to 12 N.m (106 lb in).
6. Install the new vent valve, P/N 10382105, to the bracket.
7. Reinstall the electrical connector.
8. Reinstall the canister vent valve hose.
9. Lower the vehicle.
10. Clear the DTC.
ASE Master Tech, L1 Advance Engine Performance certified
I will not answer repair questions by PM, if you would like my input you can PM me and ask me to reply to your public thread.