More 4X4 - Plus Air

[bobfronk]

I am new here and have read a few of the threads about the 4X4.

I want to try and fix this myself this time as 3 yrs ago, it cost me $1000. At the time, the 4WD buttons would not work at all. I believe they replaced the module under the passenger side dash and also on the transfer case itself.

Now it is doing pretty close to the same thing.

I have the "Auto 4WD" - 4WD HI - 4WD Lo - 2Hi buttons. If I select "Auto" it will appear to engage. However, if I am driving in "Auto 4WD" and start to go up a hill or try to pass someone, the light will blink and it will change by itself back to "2HI". It does this if in 4WD also.

Also, when I go up a hill, or press the pedal hard, it is like I opened the air vents. Air starts blowing in the cabin until I am on level ground again, or back at a cruising speed.

From the threads here, it seems that I could replace the module under the dash, but I just want to confirm. Also, does anyone know the cost of this?

Also, any chance that this could be a problem with the PVC valve?

Thanks and Merry Christmas!

[blazer_guy86]

First of all you need to specify a year model here. I assume it's a 98 or newer considering it has the auto 4wd feature. The first thing i would do is disconnect the negative battery cable for about 10 minutes. This will reset your transfer case control module. (tccm) If it works after that you probably have a failing tccm. Also check all vaccume lines.

Now as far as air coming through your vents. Air will flow a little fast but not much faster when you speed up due to a little extra pressure on the front of the vehicle. This should not be related to your 4x4 problem.

BTW, welcome to AF.

[bobfronk]

It is a 2000. Sorry, I thought I put that in there before.

Anyway... Both problems were due to a cracked vacum hose. It was the bottom hose on that little vacum switch mounted to the firewall on top of the engine (right in the middle).

I just cut off the cracked area and now 4wd is working well. The inside vents are working correctly now too.

[rlith]

You should replace that entire section of hose (actually all the hoses) because now that they're dry it's just going to continue to be an issue

[bobfronk]

Yes, I will probably do that once it warms up a bit, or at least stops raining.