4wheel drive service light comes on

I had a similar problem with the Service 4 Wheel Drive light which came on intermittently then became more consistent in the message center display. It would go into 4 wheel drive if the message center did not display the Service 4 Wheel Drive message in the message center, but not when the message was displayed. I found the transfer case switch module in the dash was defective, and it has been working with no other problems for three years.

THE TRANSFER CASE MOTOR IS NOT WORKING TO INGAGE 4 WHEEL DRIVE. CHECK WITH DOOR OPEN WHEN YOU PUSH 4 WHEEL SWITCH YOU SHOULD HEAR MOTOR INGAGE 4 WHEEL DRIVE. IF YOU HEAR MOTOR BUT STILL NO 4 WHEEL DRIVE THE GEAR ON MOTOR COULD BE DAMAGED. REPLACE TRANSFER CASE MOTOR.

Sounds like the chain in the transfer case has broke or the linkage is out of adjustment

The service 4 wheel drive light is indicating a part failure in the 4 wheel drive system.
Take your vehicle to your local Auto Zone or Advance Auto Parts and ask them to scan your Tahoe for trouble codes. The code will help to determine what the component failure is and you can start diagnosing at that point.
Write the code down and reply back, we can go from there.
Good luck.
Regards,

GM has extened the warranty for this to 7 years or 70,000 miles which ever comes first. See your Chevy dealer

try shifting while trans is in neutral-might be bound up at the servomotor-

HAVE YOUR PLUNGER FOR THE DIFF CHECKED IT SHOULD BE UNDER THE BATT TRAY

There are well over 100 problems in the electronics that turn the service engine soon light on, go to autozone or a kragen and they will run the trouble code test for free, then record that code and post it here. As far as the 4X4 goes that problem is most likely the electric motor that engages the 4X4 tranfer case, u will have to have that tested by either a 4X4 shop or the dealer, the dealer is the best option.

the shifter accuator or the wires going to it on the transfercase..gl