Chevrolet Silverado 1500 / 2500 / 3500:

Service 4WD Light

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# 1  1/10/2012 11:15 PM

rodh
New member
Registered: 1/10/2012
Posts: 4

Service 4WD Light

I have a 2005 Chevy Silverado 1500 HD with a 6.0L engine.The light comes on intermittently and has come on twice at startup in the last week. Usually it comes on and the 2H light is still on but you can't switch the T/C. When it came on at start up no lights were on at all. Been browsing the websites and have heard many reasons for this situation. Most topics say what I assumed and that it is hard to diagnose without the TBC. Took the truck in this morning and got the code read at the dealership. I am more confused because the 2 techs were disagreeing the possible problem. The code is C0327. One tech says that it is the seal for the encoder motor and requires Part #012547464 and requires the T/C to be pulled to fix. The other tech feels that is only the switch on the dash because it seems to come on (THE 4WD LIGHT) when I hit a large bump or rough road and also said that the T/C doesn't have to be dropped to change the encoder motor seal. Please help!

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# 2  1/11/2012 4:04 AM

TechHelp2
Administrator
Registered: 11/24/2009
Posts: 1299

Re: Service 4WD Light

The code CO327 describes water intrusion into the control module. I have the code description taken from the Alldata information website listed below.

Subject: 2004-2005 Full Sized Trucks and Utilities Transfer Case Control Module Contaminated by Water Intrusion - keywords NP8 246EAU B0790 C0300 C0305 C0306 C0321 C0327 C0359 C0374 C0379 C0550 4WD PIP3352 - (03/04/2005)

Models: (2004-2005 Chevrolet Silverado) and (2004-2005 Chevrolet Suburban) and (2004-2005 Chevrolet Tahoe) and (2004-2005 Chevrolet Avalanche) and (2004-2005 GMC Sierra) and (2004-2005 GMC Yukon) and (2004-2005 GMC Yukon XL)

The following diagnosis might be helpful if the vehicle exhibits the symptom(s) described.

Condition/Concern:
Service 4WD light on with either a variety of DTCs or no communication with the transfer case control module.

Recommendation/Instructions:
Inspection of the transfer case control module (TCCM) may reveal the connector to have evidence of water intrusion. The most likely cause of this water intrusion is a leak from the windshield to body seal.

Repair the water leak as necessary.

Please follow this diagnosis process thoroughly and complete each step. If the condition exhibited is resolved without completing every step, the remaining steps do not need to be performed.

Have the dealer follow this trouble description and investigate the water leak that may of dripped into the control module.

The actuator can be replaced with out taking the transmission out. The labor time is less that an hour. The price of the actuator can be shocking.

I hope this helps.


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# 3  1/11/2012 5:11 AM

rodh
New member
Registered: 1/10/2012
Posts: 4

Re: Service 4WD Light

Thanks Techhelp2. Unfortunately now you have given me a third issue to check. Chevy is telling me code c0327 is an encoder motor malfunction. With the amount of topics I am finding on these sites I am beginning to believe they dont have a clue what they are doing with this problem

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# 4  1/11/2012 1:11 PM

TechHelp2
Administrator
Registered: 11/24/2009
Posts: 1299

Re: Service 4WD Light

The CO327 is the encoder code but the water intrusion should be looked into first. The encoder is expensive, you could have a bill at about 600 dollars minimum.

After the control module is inspected and water intrusion is ruled out then the encoder motor becomes the issue.

Keep us informed on the situation if you can.


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# 5  1/11/2012 3:33 PM

rodh
New member
Registered: 1/10/2012
Posts: 4

Re: Service 4WD Light

I will keep you informed. The TCCM is located behind the head lamp switch correct. I may have a look at it myself because the tech at the dealer is telling me he has never heard of that happening or that it could be the reason for the code. I may even get it up on my friends hoist and separate the encoder motor assembly from the T/C to see if there is a fluid leak there causing the sensor to act up. Looks like it is not that difficult to do. If it is leaking how difficult is it to replace the seal/bearing the dealer is referring to. $600 labor seems a bit much for a $25 part.

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# 6  1/12/2012 3:11 AM

rodh
New member
Registered: 1/10/2012
Posts: 4

Re: Service 4WD Light

Hello again. Yesterday had dealer change tranny cooler line and then pull the T/C codes. Like I mentioned he found code C0327 and told me the seal behind the encoder motor was the problem. Thanks to your help with the other TBS notifications from you and others on other sites seems like I found my issue. This morning on my way to work the brand new cooler line let go and I had to get the dealer to send out the tow truck. I was rather upset and missed a day of work. By the time I was done I got my line fixed AGAIN and the TCCM inspected, the 4x4 switch replaced, and finally the fix which was a damaged encoder motor sensor and guess what no leaking seal. one terminal on sensor was broken almost off the sensor. And the best part all done for $0. To boot a written guarantee that if I have tranny problems in the next 25000 km with the line blowing I will only have to pay labor no parts. It really pays to go in with your homework done. THANKS a lot guys for all your help.

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# 7  1/12/2012 3:28 AM

TechHelp2
Administrator
Registered: 11/24/2009
Posts: 1299

Re: Service 4WD Light

Glad we were able to assist you with your problem. Thanks for the update, if you need us again we will be glad to help in any way we can. Good luck.


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