Will the envoy quit working when the 4wheel drive service light is on?

Answer 1

Probably. But it depends on the problem. The light is on because the computer detected a problem. There will be a code, or codes. Without a scanner you're looking for a needle in a haystack. If you want to see if the 4x4 works either find some gravel put it in 4 wheel drive and tromp on it like your racing the kid on your street with the tricked out civic and the big cockeyed hat on his head and see if the front wheels spin. Or just do some tight turns with the 4x4 on, you should feel it if it's working. The switch is a common failure. Another thing you can try: The control modules on them go to sleep. Don't laugh, those are GM's very words in the TSB they produced. In the under the hood fuse panel look for a fuse labeled ATC, ACT2, or Sometimes ETC . Pull the fuse. DO NOT ever pull a fuse with the key on. It can cause a voltage spike with nasty results. Turn the key on and leave it on for at least 30 seconds. Next, turn the key off. Then, reinstall the fuse. Again, I have to reiterate...don't ever put a fuse into a panel with the ignition on. The spike theory again. Start the vehicle and see if the light goes out. If it does take it for a drive and try putting it into 4x4. if the light comes back on you just cleared the code (s) and they came back, In that case you can repeat the procedure with the other mentioned fuses. There is usually at least 2 of the 3. It's a fairly common problem.