No lights on 4WD Switch. No service 4WD light on dash.

[G450Driver]

I have a 99 Tahoe 4X4 Z71 LT. My old 4WD drive switch was flickering and randomly lighting up in different modes without anything actually changing for awhile. Then one day it just went dead. I replaced the switch and it was fine for about a week. Now the switch is dead with no lights and no function. Could this be a bad transfer case control module? If not does anyone have any ideas?

 

[Mean_Green]

Replaced the switch with one from where?

Have you tried to put the original back in?


When I first got this, none of the LEDs worked. I pulled it apart and found a bad solder trace. Re-flowed that and they all worked. Ended up replacing it anyways since some of the plastic was broken out.

 

[Miami-Dade]

Welcome from Miami&NYC!

Moved you over here since this is not a lifted question.

 

[G450Driver]

Replaced the switch with one from where?

Have you tried to put the original back in?


When I first got this, none of the LEDs worked. I pulled it apart and found a bad solder trace. Re-flowed that and they all worked. Ended up replacing it anyways since some of the plastic was broken out.

I replaced the switch with a Dorman. It worked great, then nothing. After I replaced the switch it went into and out of 4WD with no problems for about a week. I went out of town for 8 days and when I came back it didn't work when I fired it up again. I didn't try the original switch again.

 

[Hoesgottaeat2]

Not to be insulting, but are you sure that nothing is being actuated by the switch? (3) of the (4) OBS’s I have owned have had flickering 4x4 switches and randomly the light would go out. But they still actually did their job of switching consistently.

And greetings, welcome to the forum from NY.

 

[G450Driver]

Not to be insulting, but are you sure that nothing is being actuated by the switch? (3) of the (4) OBS’s I have owned have had flickering 4x4 switches and randomly the light would go out. But they still actually did their job of switching consistently.

And greetings, welcome to the forum from NY.

No offense taken. Yeah I'm sure. When it's working you can clearly hear the actuators doing their job. Now I get no response. I know the lights work because they all illuminate when I initially turn the key on. But after that they all go out. I feel like the TCCM is the problem. I'm in denial because I can't figure out how to get in there with my hands to disconnect the electrical from the module

 

[east302]

I’d probably try that original switch again.

The GM service manual has the wiring diagrams and diagnostic procedures for the transfer case, module and switch. I don’t think there is one for 1999, but the one for 1998 would probably suffice.

It’s in volume 2 of 4 of the PDF files here:

88-98 Service Manuals

Over the years I have collected a bunch of GM service literature. Links to PDF Scans of service and STG manuals and a links to the Parts manuals. You'll need the FREE Adobe Acrobat reader to open these files. Get it directly from Adobe here {http://get.adobe.com/reader/} If you're not...

www.gmt400.com

 

[G450Driver]

I’d probably try that original switch again.

The GM service manual has the wiring diagrams and diagnostic procedures for the transfer case, module and switch. I don’t think there is one for 1999, but the one for 1998 would probably suffice.

It’s in volume 2 of 4 of the PDF files here:

88-98 Service Manuals

Over the years I have collected a bunch of GM service literature. Links to PDF Scans of service and STG manuals and a links to the Parts manuals. You'll need the FREE Adobe Acrobat reader to open these files. Get it directly from Adobe here {http://get.adobe.com/reader/} If you're not...

www.gmt400.com

I'll take a look. Thank you!