95 GMC Jimmy 4 wheel drive problem. please help

my 95 gmc jimmy is having some 4 wheel drive issues. it has the push button 4wd. it will go into 4 wheel low fine, but when i press the 4 high button both low and high lights flash for a few seconds and then it goes back into 2 wheel drive. does anyone know what could be causing this? your help is greatly appreciated.


also, i have only had this jimmy for about a week and do not have the owners manual. can someone tell me the proper way to put it into 4 wheel drive? does it need to be in neutral or can you just shift on the fly (10mph or less)?

thanks.

Use the search button. There are about 4 of these threads currently active on the jimmy/blazer/s10/sonoma boards...

This has been covered a million times...:)

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.

my 95 gmc jimmy is having some 4 wheel drive issues. it has the push button 4wd. it will go into 4 wheel low fine, but when i press the 4 high button both low and high lights flash for a few seconds and then it goes back into 2 wheel drive. does anyone know what could be causing this? your help is greatly appreciated.


also, i have only had this jimmy for about a week and do not have the owners manual. can someone tell me the proper way to put it into 4 wheel drive? does it need to be in neutral or can you just shift on the fly (10mph or less)?

thanks.
u can shift from 4x4 hi and 2wd on the fly (don't engage 4x4 over 45mph). to shift to and from 4x4 low the vehicle needs to be in park or neutral or traveling at less than 3mph. wait till the light stays solid before continuing on.

rlith pretty much answered ur other question.
hope we were able to help.

I was having similiar problems with my 4wd. If it was in neutral it would shift into 4 lo, but not 4hi it would just blink as you stated. After reading several posts on the blazer site as well as this one, i removed the electrical connector on the transfer case(is held together by a 8mm bolt.) and water came pouring out of the pin sockets. I also found several of the male pins had "white fuzz" (corrosion). I used electrical cleaner, compressed air, and alot of time with scotch brite on the pins. Before i put it back together i used Dow Corning 4(similiar to the electrical sealant you buy to put under spark plug boots.) on the pins. After that everything works great. Hope this helps some. This 4wd system makes me appreciate my Jeep even more:) This site was a huge help to me, thanks for all the help everyone.

glad we were able to help you but this thread is now over a year old. please refrain from posting in older threads :nono: .