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GM Tech (Cam)
GM Tech (Cam), Chevy Technician
Category: Chevy
Satisfied Customers: 29396
Experience:  GM Grand Master Technician 2007. 14 years experience.
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Chevrolet Silverado 1500 HD LT: service 4wd on dash. i replaced

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service 4wd on dash. i replaced the sensor in the encoder motor . when i turn key on all lights on 4wd switch light up. when running the auto button stays lit up. ive tried disconnecting battery and the 4wd fuse. any other ideas?

Hi, you may be having a problem with either the switch in the dash or the module that controls the 4wd. The first thing i would recommend is having the module scanned by someone who can access the data. Not every scanner will do this. A dealer has a tech2 which will. If you can get any codes and post them here i would be happy to help you further diagnose your problem. Let me know. Thanks, Eric
Customer: replied 4 years ago.
i took switch apart and solder looks fine
Its not necessarily a solder joint problem with the switch. They sometimes put out two signals or more at once and cause the module to "lock up". But it could also be the module itself. Thats why i suggest you have it scanned first. Thanks, Eric
Customer: replied 4 years ago.
I am using this service as a last resort to avoid going to a dealership.
I understand that you may not want to go to a dealer, but i dont want to guess at what might be wrong. Wish you would have asked for more info/assistance before giving me negative feedback. Ill opt out and let another expert help you. Just relist your question again and someone else will help you shortly. Thanks, Eric
I’m a moderator for this topic. Your Professional has opted out and I wonder whether you’re still waiting for an answer. If you are, please let me know and I will do my best to find another Professional to assist you right away. If not, feel free to let me know and I will cancel this question for you. Thank you!
Hello, I'm Cam. At anytime during our discussion you need more information or clarification, please reply.

First off we have started on a new rating system for the website. Please hold your rating until the completion of our conversation, and use only the reply to expert link to reply to me for further information.

Have you checked the wiring to the module from the switch yet?
Customer: replied 4 years ago.
Not sure where module is located. I checked wires that plug into switch. Last nite i pulled encoder motor off again and cleaned up corrosion on motor wiring. Alot of corrosion and some rust on motor itself, i turned key on and pushed and held 4wd button and could here a noise under pickup from encoder motor , but it did not engage. Only auto 4wd light stays lit,
The module is under the dash, left aide above and behind the parking brake pedal assembly.

Did you check the transfer case fluid itself?
Customer: replied 4 years ago.
Did not check transfer case fluid, underside of pickup is very clean and dry, but i will check fluid this evening when done working. I will also check wiring all the way down to module
Please do, and let me know.
Customer: replied 4 years ago.
Transfer case fluid is full. Checked wiring and connections and did not notice anything bad or corrosion on connections.
Color is very important, however I also need the exact color. For instance, if the fluid red, black, or does it have metal particles in it?
Customer: replied 4 years ago.
It is black and thinner than i expected
Am I right to assume it stinks as well?
Customer: replied 4 years ago.

Do you think changing the fluid will solve the problem?

No, but it is an Indication of issues so drain it and see if there are chunks in he bottom hole or metal debris. P
Customer: replied 4 years ago.



Rebuild the transfer case. The clutch in there is cooked and the travel will run the sensor out of range.
GM Tech (Cam), Chevy Technician
Category: Chevy
Satisfied Customers: 29396
Experience: GM Grand Master Technician 2007. 14 years experience.
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