Will my 4wd stop working if I don’t use it for a few months?

 

No.

What year Blazer do you have and is it a 3-button or 4-button transfer case? The latter has the Auto 4wd option.

The most common issues with 4wd on our Blazers are the transfer-case control module (TCCM) and under-hood vacuum lines that are leaking due to the hoses deteriorating.

 

My blazer is a 98 and it has the 3 button transfer case. The transfer case was replaced less than a year ago. Will not using the 4wd for several months or a year or more cause it to stop working?

 

No. There is no reason the 4wd will not work after not being used for a while as long as all the components are working properly.

If the transfer case had been recently serviced, perhaps one of the connections to it, vacuum or electrical, has come undone?

When the vacuum system no longer can hold a vacuum, you will almost always have issues with your ability to control which of the HVAC outlets are used, e.g., you want defrost but you only get heat.

So, what are the symptoms? Are the controls acting as if the 4wd is engaged but you only have drive at the rear wheels?

The connector to the TCCM can become corroded and the TCCM can also fail. When failing or if there is a bad electrical connection, the TCCM will click repeatedly (these are the relays) and the indicator lights on the dash will not indicate the the 4wd mechanism is working. The TCCM is located under the passenger side kick-panel.

Another possible problem is if the mechanism that engages the front axle, which is supposed to happen simultaneously with the engagement of the transfer case, is not working properly.

The front axle mechanism consists of a vacuum actuator that pulls on a cable that pulls a gear into place so that the passenger side front wheel is no longer free-wheeling and instead is mechanically connected to the front differential.

On my 99, this vacuum actuator is located under the battery tray. I think it might be similarly located in yours.

This mechanism can fail by a vacuum leak in the hose to the actuator, the actuator leaking, the cable becoming disconnected from the actuator or breaking, or the gear in the axle being worn down.

My suggestion is to do thorough diagnosis to determine what part of the system is working properly. There are threads on this that you should try to find.

 

My 4wd is working. I have not been using it since I have not been off roading, and I live in NY but we haven’t got much snow this winter. I just wanted to know if it would eventually not work if I don’t use it.

 

As everyone has said, there is no reason why non-use of the 4wd will cause it to not function. Most everything is turning when in 2wd, just that the right front is not engaged to the front differential and the transfer case is in neutral so no power is transferred to the front differential, although the left front axle turns the differential which turn the front driveshaft. I think everything is turning within the transfer case, but the gear that engages the input shaft to the front driveshaft is not meshing.....very similar to the how the right front axle engages when in 4wd.
(Now you know why a 2wd Blazer gets better fuel mileage than a 4wd Blazer)
Using the 4wd whenever possible is a good idea to make sure it will work when you need it....as that is not the time you want to find out it is not working.

 

I am confused. First you say there is no reason not using 4wd will cause it to not function, then you say use it whenever possible to make sure it will work.

 

OK...let me try again.....there is no component of the 4wd system that needs to be "exercised" that will ensure it will function. There is always the chance that something will fail within the system; vacuum actuator or hose, corrosion of an electrical connector, etc. Using the 4wd will not stop an actuator/hose from rotting or prevent corrosion within an electrical connector. But if you use the 4wd system when you do not need it, will give you time to repair it so it is ready for when you do need it.

Hope that makes sense.

 

1998 Blazer Lt 4dr

Hello. I have the 3 button 4 wheel drive. Can I put it in 4 hi while it is in park?

 

Push the button and see what it does. It won't hurt anything.