Location tccm 04 avalanche z71 - 2004 Chevrolet Avalanche

A vacuum leak would cause the check engine light to come on and throw a code. It is more likely mechanical. Ideas in the link.

https://www.google.com/search?q=2005+Chev+Avalanche+Z71+-+whistle

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Question edited for clarity.
Question moved from Spanish car company Seat, (pronounced See-At).

Check out the link

https://www.google.com/search?q=2006+HOLDEN+RODEO+RA.+LOCATION+of+TCCM

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4x4? Check driveshaft and differentials

Nathan, 2 Knock's are located under intake manifold.
Check the attached links,
"I hope this helped you out, if so let me know by pressing the helpful button. Check out some of my other posts if you need more tips and info."

How To Install Replace Engine Knock Sensor 2000 06 5 3L Silverado Sierra...

Knock sensor 5 3 4 8 6 0 replacement

05 Chevy Avalanche Knock Sensors

4 8 5 3 6 0 knock sensor replacement GM

Have the TCCM scanned for codes.

you need to replace the tccm and get it programmed.


2-04-21-006E: Inoperative 4WD/AWD Lamps, Inoperative 4WD/AWD System, DTC C0550 Set No Communication with TCCM (Reprogram Transfer Case Control Module) - (Jul 20, 2006)
Subject: Inoperative 4WD/AWD Lamps, Inoperative 4WD/AWD System, DTC C0550 Set, No Communication with TCCM (Reprogram Transfer Case Control Module) Models: 2004 Buick Rainier 2002-2004 Chevrolet TrailBlazer, TrailBlazer EXT 2003-2004 Chevrolet Avalanche, Silverado, Suburban, Tahoe 2002-2004 GMC Envoy, Envoy XL 2003-2004 GMC Sierra, Yukon, Yukon XL 2004 GMC Envoy XUV 2002-2004 Oldsmobile Bravada with Electronic Shift or Active Transfer Case (RPOs NP1, NP4 or NP8)

This bulletin is being revised to add Subject information and change the labor operation. This bulletin cancels and supersedes Bulletin Number 03-04-21-006. Please discard Corporate Bulletin Numbers 02-04-21-006D and 03-04-21-006 (Section 04 -- Driveline/Axle).
ConditionSome customers may comment that the 4WD/AWD indicator lights on the selector switch do not work, or the 4WD/AWD system may be inoperative and/or the service 4WD light is illuminated. The condition is typically intermittent and always occurs at key-up. Upon investigation, the technician may find DTC C0550 set.
CauseThe Transfer Case Control Module (TCCM) has not received the wake-up call during key-up and has remained in the "sleep mode".
When the TCCM is in the "sleep mode", it will not communicate with the class II bus or the Tech 2®.
Correction

1. Try to communicate with the TCCM. If no communication, go to step 2. If communication is possible, go to step 5.
2. Remove the underhood (ATCM or TREC) TCCM fuse.
3. Wait 30 seconds.
4. Reinstall the fuse. The module should "wake up" and communicate with the Tech 2®.
5. Check for codes in the TCCM. If a C0550 is found current or in history with or without other codes, replace the module and go to step 6.
6. Reprogram the TCCM with the latest TIS software using normal SPS procedures.
7. Verify operation and that no codes are present.

Important: For the 2002 model year, the TCCM must be replaced and reprogrammed.
Warranty Information

Hi, a P0446 means Evaporative Emission Control System Vent Control Circuit Malfunction

Full details @ http://www.obd-codes.com/p0446

There is a TSB on this problem: TSB #03-04-21-001C

Subject:4WD Switch Indicator Lights Flashing, 4WD Inoperative, DTCs C0327, P0500, P0836, P1875 Set (Replace Encoder Motor Sensor, Reprogram TCCM, Inspect Front Drive Axle Engagement Sleeve for Damage/Repair) #03-04-21-001D - (12/04/2003)



Models:2003 Chevrolet Avalanche, Silverado, Suburban, Tahoe
2003 GMC Sierra, Yukon, Yukon XL
with 4WD and Electric Shift or Active Transfer Case (RPO NP1 or NP8)
You can also try removing the TREC fuse (engine fuse box) and reinstall after 30 seconds. Look up the TSB number I gave you and you'll find alot more information.

The switch is on the drivers side, above the pan, where the cable attaches, but I dont think that will get the trans moving.

Have you received any failure codes (check engine light)? If you have, find out what they are by going to any parts store and they can read your failure codes for free. Let me know after that.