Starter System Issue?

No, the air injection pumps are pass side on my truck and they pump clean air into the exhaust to dilute the exhaust gasses.
HVAC fan is possible though.

 

I did that about a week or so ago, had to pull the intake manifold to get to them, but once disconnected the hum persisted. I had at the time thought the sound was from them but then when the starter turned up burnt to a crisp I figured that was it. I wish was there was a fuse a or relay for the saips to make it easier

 

Your talking about the valves and I'm talking about the actual pumps. They are in the fender well.

 

Fan isn't likely as the sound would be greater inside the cab than outside.

 

Remove fender liner to see the pumps

 

Is the connector for the pumps the one in front of the coolant reservoir?

 

That I don't know. Never had time to really dig into my truck yet. Can't hurt to try it, just don't break clips messing around excessively.

 

There are 2 - one by the reservoir and one by the airbox. Disconnected both, still a hum.

 

Are you certain those are what feeds the pumps?

 

Is the washer fluid pump running?

 

Yeah, just watched a video on it.
Washer pump is good, replaced that a few months ago.
Sliding around under the truck trying to track it down, the sound is most prominent laying under the transmission/gearbox area. I have no idea what it could be. I can't feel any vibrations in anything, it sounds just like a pump whining and it's not the fuel pump. (Fuel pump is new, and the sound is doesn't emanate from the tank, and sounds different when it's on)

 

Maybe the 4x4 shift mechanism solenoid, try to cycle 4x4 and listen both on and off, maybe low too.

 

Fuel pump only runs with truck started

 

Hm, I was just reading something about that yesterday, maybe when you mentioned the faulty ignition switch or something.

 

Oh it was a ground strap a few people had found broken. Mine still looks to be good

 

Cycle that 4x4 and have a listen

 

Had someone cycle while I was under, it made all the appropriate noises but didn't seem to affect hum. Is that solenoid internal or external?

 

There are two actuators, one to put transfer case in 4 lo and the other to engage front differential.

 

They could have some sort of internal limit switch that could fail and cause the motor to run full time, again I don't know enough about em yet to be certain. Lots of threads here on the site and I have seen a few posts about repairing and rebuilding, just don't recall all the details.