2001 suburban 4wd makes a humming noise

[griz1248]

My 4wd makes a humming noise only when it is on 4hi. In order for me to make the noise go away i have to switch to 2wd and turn the truck off then back on. Any information would help out alot.

Another concern i have is that my suburban wouldn't start on 2 different occassions. Both incidents being about 3 months apart. On 1 of the incidents a jump start helped out. But recently i went to go start my suburban and nothing; not even a turn over. So i go to ask for a jump and still no positive results. So 15 minutes go by and i try again. The burban starts up like nothing ever happened. My security light comes and goes when it feels like. Could these two problems be related in anyway. Everything on my suburban is stocked. But i did notice that the owner before me had a amplifier hooked up cause he left his wires still hooked up.

If anyone could give me any suggestions, i would appreciate it. Like they say a a good mechanic likes a knowledged owner, a bad mechanic doesnt.

[kenny-1907]

The intermitent start problem may be related to the passlock module. I could be wrong

[griz1248]

I was doing some research and found out that; on many GM vehicles with the Passlock II feature, the ignition lock cylinder fails, causing the theft system to go nuts.

A mechanic suggested to me........ that my key can be worn out causing the security light to come on. I did buy my suburban used. So can that be a possibility?

thank you for your reply.