2002 GMC Suburban wont . Low fuel light came on I instantly put $25.00 E85 in drove and ran errands. start n stop about 3 times then went back to work and parked it. Came out 2-1/2 hours later won't start. Lights flashing on dash and wheel drive indicators. Turns over strong but wont fire. Can hear a motor in my back seat humming

SOURCE: wont shift back from 4x4 low, to 2x2

I also have a 2002 Envoy. Shifting to and from 4wh and 4wa can be done on the fly but shifting to 4wL has to be done stoped and while in neutral. Try that. Otherwise I'm afraid its a new computer for you. Its located under the left rear seat and you need a loan for one.

SOURCE: I have a 99 GMC Jimmy with the 4 wheel drive. I

check fuse and relay to switch if power to switch retest switch new doesnt mean not defective if no power check connections and wiring for damage or breaks

SOURCE: My 2002 GMC Envoy wont start. I have had it on

try car to car boost-battery charger may not be working correctly or set on low amp charge -interior lights and dash may all light but battery may not be strong enough to energize starter have battery tested if battery good than check for power to the starter if power-- starter may be shot can remove also and have tested at most auto stores free if no power battery -wiring-or connection issue would need to test fuse panel-ignition switch and starter solenoid

SOURCE: 99 gmc denali dash light, parking lights, tail

You have a short to ground somewhere in the drl-fog lamp circuit. Check for obvious wiring connector or wiring to drl & fog lamps. check wiring for pinched or broken wires coming from sockets. If you don't find problem, you can trace wiring from lamps to main harnesses and hopefully find source of short.
hope this helps.

SOURCE: My 2002 Gmc Envoy is stuck in 4wheel low. I

Before you spend a ton of money check the switch in the dash. Sometimes the metal just doesn't connect.