Help with 4 Wheel

I am having trouble with my 4 Wheel High. My low works but the high just blinks a few times but won't go into gear.. Any suggestions from anyone..
Thanks Angel

I check for a vacuum leak first. What are the details of your truck (year, model, etc.)?

I'm having the same problem right now with mine, I found a hole in my vaccuum line though. It was right next to the exhaust and lead up to the vacuum pump under the battery compartment.

The thing under your battery is the vacuum acuator. To test it you can tap into any vacuum hose with a tee. Run a hose from the acuator to the tee in the vacuum line. This should make it draw in and pull the cable that ingages the front end. This is what turns the light on inside your cab that shows it is in 4wd. If this works you have either a problem with the vacuum lines or you have a bad actuatot switch that is on the top of your transfer case. The switch is a very common problem. I have mine replace every other year. This is what the switch looks like. The vacuum hose runs from the intake down to the switch and then up to the acuator.

http://i5.photobucket.com/albums/y196/ZR2/switch.jpg

If you used the search button, you would have seen this has been covered thousands of times before....sigh

1st Check vac actuator under battery tray for tears, or leaks, and that the vac hose is connected. Replace if found

2nd Check vac hose leading from vac actuator to vac switch on transfer case for cracks and dry rot. Replace if found.

3rd Check remaining 2 hoses from vac switch on transfer case for dryrot or cracks Replace if found.

If all of the above are fine, disconnect your negative battery cable for 1/2 hour then reconnect it. If your 4x4 works after that you probably have a failing TCCM (Transfer case control module)

If that doesn't solve it, it's most likely the encoder motor