With my 2000 blazer 4x4( 4 button switch with NV236 tcase) my 4hi switch will only blink for a few seconds then go back to 2hi. If I try 4lo, it will click the TCCM a bunch of times, then kill all power to the switch. I removed the battery tray to see if actuator was working. Found that previous owner had run the vacuum hose for the actuator, straight to the intake. So I fixed that issue, but now 4wd still. Actuator functions for a few seconds when pressing into 4hi, but will go back to original position. Please help….

 

Have you checked the transfer case control module (TCCM)? The electrical connector can become corroded and the internal relays can go bad. This results in the sounds of clicking coming from the passenger side kick panel where the TCCM is located.

 

So you have the switch panel for 2 wheel drive - 4 wheel drive - 4 wheel drive low and auto 4 wheel drive

On my car the light diodes in the switch just blinked or did not work as did other switches like for the windows, mirrors and so on.

What i did was to take off every switch, take the switches with me inside and i opened up every switch and cleaned every contact surface on them.
I also did some resoldering on the switches including the the switch panel for 2 wheel drive - 4 wheel drive - 4 wheel drive low and auto 4 wheel drive

After i cleaned and resoldered the switches all of the switches worked like brand new swiches on my car The 2 wheel drive - 4 wheel drive - 4 wheel drive low and auto 4 wheel drive was also working as it is supposed to after i cleaned and resoldered the switch

I also took out the solder board in the keyless remote and cleaned the contact points on it and after i did that the keyless remote worked like the car was brand new.

On my car the problem was in the electric switches and nothing else.

If you still have this proble clean the switch and check the solder points on your car

I hope this can help you out fixing your car

Here you can see the switch and the solder points (to the right for the pencil) that i resoldered. Also clean every contact point on the switch

Re-solder the points to the right for the the pencil


This is the switch i am talking about