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Pete, Auto Service Technician
Category: Chevy
Satisfied Customers: 27812
Experience:  14 years GM dealer Technician.
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I'm ***** *****. my diag nightmare is with a 96 Yukon 1500

Customer Question

Customer: I'm ***** *****. my diag nightmare is with a 96 Yukon 1500 4x4.
JA: Thanks. Can you give me any more details about your issue?
Customer: Here goes.... No 4HI. 4LO was also inop until tccm replaced. I can get 4HI by going 4Lo first then to 4Hi but it's inconsistent and when it does it lights both 4"s up. Also 2HI never lights. details as follows. tccm and encoder replaced twice. Switch also tested good and replaced just in case. 4HI works spinning on rack manually selected with encoder off. All lights flash with key cycle. Had a code 12, tested per alldata chart, code is gone now. Don't know which wire on encoder to check for 4HI signal. Hoping I'm not battling two bad tccm's in a row. Power and grounds check good.
JA: OK got it. Last thing — Chevy Mechanics generally expect a deposit of about $18 to help with your type of question (you only pay if satisfied). Now I'm going to take you to a page to place a secure deposit with JustAnswer. Don't worry, this chat is saved. After that, we will finish helping you.
Submitted: 1 year ago.
Category: Chevy
Expert:  Pete replied 1 year ago.

My name is ***** ***** I am a professional here at Just Answer. I noticed that your question had not received a response and thought I would see if you still need help with this.I apologize for the delay and I hope I can still assist you with this here.

Inspect the connection at the encoder motor and make sure it isnt corroded or damaged as well as no terminals are spread open and damaged needing replaced.I have seen this cause this type of fault here before.One of the biggest issues on this model I have seen is the encoder will short out and damage the TCCM.If the TCCM is replaced before the encoder is replaced the faulty encoder will damage the new TCCM right away.So if you replaced the TCCM before you replaced the encoder there is a chance that the new TCCM is damaged needing replaced again now that the encoder motor has been replaced.

If more help is needed, use the reply tab to continue our conversation. If no further assistance is needed, kindly rate my service.You can rate at any time and we can continue to work on your question as this will not close out your question.Keep in mind in some cases it can be difficult to fully diagnose or help repair your vehicle without seeing it and I work on delivering the best possible answer from what I see to work with.

Thanks Pete

Customer: replied 1 year ago.
Thanks Pete. I found the tccm is the wrong part number, it shows for a s10/blazer even though connector and bracket the same. Anyway I ordered a gm module so to be continued till next friday. Fingers crossed
Expert:  Pete replied 1 year ago.

That is great to hear you found an issue here.I suspect this will correct the issue here.I have seen the wrong installed before that causes issues here.If your encoder motor on the transfer case is new once your new module gets here you should be good to go.

Let me know if you need anything else and feel free to rate my help here.

Thanks Pete