How to troubleshoot 4WD in a 2001 Suburban

**raydium** · 05-25-2009, 09:21 AM

Hello

I have a lot of issues with 4WD in my Suburban. First thing that happened was when I shifted to 4WD my SERVICE 4WD light came on and would not go off. Researched and guessed and replaced the console switch assembly. Now I have NO lights at all on the switch.
I also get a whining Howling noise from the front end when driving.
My Question:
When the truck in up in the air with all wheels off the ground. My front wheels are Disengaged from the front Differential. BUT should the front drive shaft be locked into gear. I can spin the front tires freely but with the engine running and in gear the front drive shaft is activated and turning. Is this correct.

Thanks
Ray

**chevythunder1980** · 05-26-2009, 05:40 PM

You may still want to get it scanned for codes. I know front diff. howling noise is common. I had one doing that but only on de-celleration. Its kind of up to you when to fix it, depending on how noisy it gets. dont think it has anything to do with the 4WD light though. If it doesnt bind while turning on dry pavement in 2WD, but does in 4WD, then its probably working normally.

**MrShorty** · 05-27-2009, 10:59 AM

When the truck in up in the air with all wheels off the ground. My front wheels are Disengaged from the front Differential. BUT should the front drive shaft be locked into gear. I can spin the front tires freely but with the engine running and in gear the front drive shaft is activated and turning. Is this correct.

Depends on what t-case you have. This is normal for the 246 (aka autotrac) because of the pre-load on the autotrac clutches in the transfer case.

**raydium** · 05-29-2009, 06:50 AM

This is a 2001 Suburban 1500 LT, it does have the Buttons on the dash for shifting. I giuss really I'm trying to find out where to start when troubleshooting this problem.
4WD service light came on while shifting, No lights at all now on the Shifting switch. Fuses good. Changed the Switch assembly on the dash. Now there is just no lights and no 4wd.

Thanks
Ray

**redneckarmyMP** · 05-29-2009, 07:05 AM

my 4wd service light comes on from time to time and when it does it wont allow me to switch back into 2wd or 4low.i was told the fluid in the front differential was low and the computer would not alllow me to switch between drives to prevent damage.try having your fluids checked.the method i had to use to switch in and out of 4wd was to turn the truck off, wait a few seconds turn it back on and immediatly push the button to get out of 4wd.hope this might help some