Seirra 4lo works but not 4 hi

coreyod21 · November 11, 2011

Hi my 4x4 used to work great then randomly started having problems with shifting into 4 hi. It does shift into 4 lo when in neutral like normal. When im in drive or park I try to shift into 4 hi and nothing happens. When its in neutral and I hit 4 hi I can hear the relay click but that it still no 4 hi. What do you guys think I should start with to fix this problem? My truck is a 1998 Seirra ext cab. Thanks in advance.

gmtech4 · November 11, 2011

idealy the t case needs alittle driveline movment to shift nicely ,that said there could be a number of things that is causing your concern,if the oil is/was dark the only way is first scan it if electric shift which i think it is,and

the second is to have it taken out and apart for a look inside ,i dont recommend you doing it unless an overhaul,manual is used and some mechanical experience .

any garage can give an estimate over the phone for the inspection only

good luck

BlackZ71Silverado · November 11, 2011

Hi my 4x4 used to work great then randomly started having problems with shifting into 4 hi. It does shift into 4 lo when in neutral like normal. When im in drive or park I try to shift into 4 hi and nothing happens. When its in neutral and I hit 4 hi I can hear the relay click but that it still no 4 hi. What do you guys think I should start with to fix this problem? My truck is a 1998 Seirra ext cab. Thanks in advance.

If you are not moving the truck after shifting into 4hi, that may be the problem. Many times while attempting to shift into 4hi when not moving, the light will just blink and you can hear it trying to shift like you describe but it will not engage. Sometimes it needs movement for everything to line up correctly to engage. Try rolling forward/reverse a short distance right after shifting into 4hi, it should work.

coreyod21 · November 12, 2011

thanks for the replies. I tried to shift it in 4 hi from a park to moving and while moving. Both times left me with the same result. No 4 hi. Do you guys have any other clues?