Hi all

I have no idea where to start troubleshooting this, as I have zero experience with the push button 4WD...There are a couple things going on:

1. When going into 4WD the light does not stop blinking (ie the vehicle is not detecting that it has successfully gone to 4WD), BUT the 4WD DOES engage. You can clearly feel the change, and it functions fine in use.
2. Not every time but over half it will NOT go back to 2WD. It acts as though it has, but all transmission function is lost after trying to switch back - it will not leave neutral in 2WD after being in 4WD unless I put it in 2WD, shift to neutral, shut down the engine, and restart. Upon restart shifting is back to normal.

I suspect an electrical/computer problem over a mechanical one, but I don't know where to start looking. Can anyone point me in the right direction?

 

An important piece of information is what type of transfer case you have. The easiest way to determine this is by the number of buttons on the control; 3 or 4. The 4-button one being with the Auto 4wd option. Also I believe the 4-button one can put the whole driveline into neutral; i.e. totally disconnected from the transmission which can be good for towing the truck.

If the front axle is engaging then the vacuum actuator that pulls on the cable that puts the axle into gear is likely fine. However, it is always worth checking the condition of the vacuum hoses under the hood as they can deteriorate after 15-20 years.

But your symptoms sound more like the issue is with the Transfer Case Control Module (TCCM). It is located behind the passenger side kick panel. Look for threads referring to diagnosing the TCCM for ideas. I think there can be issues with the plug that goes into the TCCM that is definitely worth looking at.

 

Check all of your vacuum lines in the engine compartment, especially the one that runs from the firewall to under the battery. They get really brittle and may look like they are connected, but hold no vacuum.

 

Hi guys. I got a 95 blazer .ı couldnt use the 4wd swıtch and ı changed ıt .ıts a 3 buttons model .normally the car ıs on the 2 hi .when ı push the 4hi the electronıc motor ıs workıng ı can hear the voıce. But ıts just blinking ı cant use the 4 hi .when ı push the 4 low electronic motor ıs workıng agaın and ı can hear the workıng sound ..and lıgh stays at 4low.so 4 wd swıtch ıs lookıng normal the electronıc transfer case ıs lookıng normal .but ı ıs not workıng ın 4 low drive.because ı also got a vakum actuator problem.ıts not orıgınal.so what can ı do ??? Please help .and thanks a lot for your time to readıng .


My broken non orıgınal vakuum actuator

 

3-button switch wouldn't flash because of axle actuator problem. Seems you have two problems. One with transfer case engagement in 4Hi, and the other a problem with the front axle actuator. Transfer case engagement is probably encoder motor. Good luck.

 

Thanks for help. But axle actuator ?? What do you mean? I am sorry but ı dont know thıs .

 

The vacuum actuator in your photo's only function is to engage the front axle - so I called it an axle actuator. Hope this explains. If not please advise.

 

If ı pull thıs vakuum actuator by my fınger and push the 4 low button , ı can use the car at 4 low. It works well I need to change the vakuum actuator and ı need to learn why ı cant use the 4 hi functıon.thanks for your time .