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Bad transfer case control module?

Tiny
ABURNETT50
  • MEMBER
  • 1998 CHEVROLET TAHOE
  • 5.7L
  • V8
  • 4WD
  • AUTOMATIC
  • 250,000 MILES
Hi, I had a problem with my 4x4 not working right I had replace the control switch then the actuator and finally I got a used transfer case control module and it still doing the same thing. I turn on my ignition switch it come on for a second and lights up for a second and nothing, afterward can't switch from 4 back to 2-wheel drive I do hear and feel a clicking sound coming from the TCCM unit.
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Tuesday, January 24th, 2023 AT 4:14 PM

7 Replies

Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 42,949 POSTS
Yep, please check the fuse "ILLM" #14 in the interior fuse panel for power here are the other fuses that need to be checked as well in the images below.

https://www.2carpros.com/articles/how-to-check-a-car-fuse

Check out the images (below). Please let us know what happens.
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Thursday, January 26th, 2023 AT 10:44 AM
Tiny
ABURNETT50
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I have 2 fuses in the box no 2 and 24 and I checked both of them. Number 2 is the main fuse that works my acuter at the transfer case at this point it only works by inserting and pulling the fuse. I have no response from the 4x4 switch at all. When I turn on my ignition switch I hear a click coming from the TCCM module and my 4x4 switch lights up and works only for a second.
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Thursday, January 26th, 2023 AT 5:29 PM
Tiny
KEN L
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There is no ILLM fuse? Here is the wiring diagram for the transfer case so you can test power and grounds.

This guide can help:

https://www.2carpros.com/articles/how-to-check-wiring

Check out the images (below). Please let us know what you find. We are interested to see what it is.
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Friday, January 27th, 2023 AT 10:57 AM
Tiny
ABURNETT50
  • MEMBER
  • 4 POSTS
It was to small to read plus I couldn't understand what I was looking at but thanks for trying Anyway, I look at the connections going to both the TCCM module and the actuator and the 4x4 switch all look good no corrosion or broken wires that I seen.
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Saturday, January 28th, 2023 AT 7:48 AM
Tiny
KEN L
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  • 42,949 POSTS
Did you click on the image to enlarge? There is no ILLM fuse?
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Sunday, January 29th, 2023 AT 1:56 PM
Tiny
ABURNETT50
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  • 4 POSTS
Yes, I enlarged the image I'm not good at reading diagrams as is and the only way my 4x4 seem to work is to insert and removed the 4x4 fuse the switch itself doesn't work it blinks for a second then quits working.
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Sunday, January 29th, 2023 AT 8:08 PM
Tiny
KEN L
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  • 42,949 POSTS
Can you remove the actuator and then work the switch to see if it moves at all? If not, you may have a defective actuator. The only other thing to do is to trace the wiring and connections.
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Monday, January 30th, 2023 AT 11:27 AM

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