Replace three transfer case control modules because they keep burning up?

PERRY MORRIS

MEMBER
2000 CHEVROLET SILVERADO
5.3L
V8
4WD
AUTOMATIC
245,000 MILES

Four wheel drive doesn't work. Replaced encoder motor brand new, replaced front differential electric actuator brand new. Replaced push button in the dash brand new. And replaced transmission control module. Besides steering column left side four wheel drive works fine only for short. Of time on the first drive doesn't matter in Auto high or two will drive within the first 10-15 minutes of driving a burning smell is smelled and then the fuse blows under the hood the 20 amp transfer case fuse but it also fries the computer when you replace the fuse the lights on the dash only flicker when you turn the key on momentarily and then there's no function out of the buttons. Then you put another new transmission control module works perfect same thing within 15 minutes smelling burn and smell pull the fuse out didn't matter still burn to the transmission control module up put a third one tested wires trying to find the fault found a 7-pin plug for hauling trailer was shorted out had mud in the plug anyway prepared that now fuses not reading short to ground but still have problem with computers burning up with everything plugged in I don't know what to unplug of replaced everything I even put the old front actuator back in and drove it and it did the same thing.

6 Replies

MASTER ASE TECH

MEMBER
82 POSTS

Hi, I'm Dan.

If I read it right, your issue is the fuse for the front drive axle actuator switch keeps blowing. I've attached a wiring diagram of the circuit for you. First thing that comes to mind for me is that the front drive axle actuator is binding and this blows the fuse. Can you unplug the actuator and drive for a day or two to see if it still blows the fuse?

If the fuse does not blow with it unplugged, then I would believe the actuator is either A) Faulty, or B) there is something mechanically wrong or binding inside the front axle itself.

Let us know what you find.

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Friday, August 27th, 2021 AT 10:53 AM

PERRY MORRIS

MEMBER
4 POSTS

The actuator on the front of the truck has been replaced that doesn't mean that it's good? But it is brand new. The last time I tried the test drive I had removed it and put the old one back in and both of them are functioning properly. I just replaced it just trying to eliminate a problem. But what's happening is the after about 15 minutes into a drive in two wheel drive just going down the highway normal driving not even messing with the four wheel drive you'll start to smell something burning and what it is is the center of the chipboard in transfer case control module it usually burns it up. Then the lights on the button go out and then the fuse blows and all this happens while I'm just driving down the highway and I'm not even trying to put it in four wheel drive. I've replaced the encoder motor brand new it wasn't OEM it was from O'Reilly's same as the controller and I've ordered the switch because on the dash ever placed it it's brand new as well. I'm going to send you a picture of the chipboard where it's damaged and maybe that will help to point me at which wires doing whatever it's doing. But thank you for responding. I've got a new transfer case control module again but I have not plugged it in because I have burned up three of them so something is definitely wrong and have not been able to locate the problem.

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Saturday, August 28th, 2021 AT 10:38 AM

PERRY MORRIS

MEMBER
4 POSTS

It's the same location that's burnt in all three of the transfer case control modules and it burns this up before the fuses blew while I'm driving down the road I'm not even messing with the four wheel drive it's just doing it by itself something's got to be touching somewhere and I don't know which wire because I power probed all of them and there's no way I can replicate the problem unless I'm driving down the highway and that's almost impossible to do I can take more pictures if necessary just tell me what will be helpful this is a 2000 Z71 lm7 5.3 I also have been getting a break and ABS light illuminating on the dash along with the service 4x4 I don't know if there's related or not but that's the problems trucks having.

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Saturday, August 28th, 2021 AT 11:18 AM

DANNY L

MECHANIC
5,648 POSTS

Hello, I'm Danny.

It sounds like you have a wire in the transfer case or transmission that is shorting to ground and causing the module to keep frying. I would inspect the harnesses to see if you can find any wires that are rubbing, arcing, melted, or showing signs of being burnt or otherwise causing a problem.

Here is a tutorial on how to test wiring if needed:

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

I've attached the wiring diagrams for the transfer case module and transmission. I've cut both pictures into 3 pieces each so you can view larger. Hope this helps and thanks again for using 2CarPros.

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Tuesday, August 31st, 2021 AT 11:56 PM

PERRY MORRIS

MEMBER
4 POSTS

Thank you for the help and awesome readable wire diagrams but still have the same issue I been leaving 15 amp fuse from under hood fuse box and only plugging fuse in for a short time to Engage or disengage the 4x4 when I need it But I recently Was re Is probing the wires with my Power probe 3 it has a Wireless short finder Still haven't mastered that though lol but I did find that there was oil leaking through the speed sensor at the transfer case front drive shaft I unplugged it and installed a fuse Is the 4x4 did work I had to shift it manually but the fuse didn't blow with the speed sensor unplugged I got another speed sensor plug it in try it out burned up another computer I had cleaned the pig tail with electrical clean. And thought I had finally figured it out Maybe It's a coincidence but I believe it's something with the speed sensor circuit That's short now and causing my transfer case Is module to burn up. How to check speed sensor circuit and why would the speed sensor circuit blow the transfer case module would be the questions I have. Thank you