Starter System Issue?

I put in a new starter and it's making the same sound as the last one- loud humming. Only hums in On position, not ACC or Off. (not sure after start, engine drowns it out).
Have any of you experienced this with your 5.7 or 2.kw starter? Is it normal?
I've checked all the grounds and everything is good. Tested the starter relay and while I don't know what the exact number(s) it should be, it tested within normal range of a 12v auto relay. Not sure what else it could be at this point.
Here's audio/video of it (might have to turn your vol up quite a bit, imgur muted the sound from the starter somehow)-

https://imgur.com/a/nRVblyZ

 

What is it doing?

 

Sorry, should have put that in there - loud humming

 

Denso replacement?

 

Yes

 

Okay. Heard that on video. Load test battery?

 

Assuming won't start. Not enough current from battery. Bad or loose cables.

 

Try to start in neutral?

 

Battery is good, starts fine

 

Always hums? After start and while running? With key off?

 

Good points too, thanks.
Do not know after start, engine drowns it out.
Otherwise
Only when key is in on position, not acc or off.

 

Key in on position, sounds to me like maybe faulty ignition switch.

 

https://www.tundras.com/threads/ultimate-tundra-wiring-diagrams-collection.81448/

 

Wonder how I could test it

 

You can use wire diagrams above and jumpers to replicate on position and see if it hums. Might check youtube and look for a switch diagram on the web for more help.

 

Hm, haven't been able to figure out what's hot when ON. I might have to pull the ignition guts out and try to figure it the old fashioned way

 

You might be able to figure out what it is by letting it hum while you pull fuses and or relays one at a time until it stops. Then go from there. Might even be able to add a switch or switch and relay into the circuit so you can switch it off and on temporarily until you can get it figured out.

 

I would pull that starter relay, set the ignition to 'On' and jump it from there. Obviously checking for the hum. I replaced my starter, but took them both to get tested before I installed the new one.

 

What would that indicate? If I jump it and it still hums you're thinking the relay might be faulty?

 

That's 1 way to rule it out.

 

What happens when you pull the relay while it is humming?

 

That's a different can of worms. When I do that several other things get set off, the fuel pump and charcoal canister I believe, as well as a couple other things that I can't identify. I think it has something to do with the IMMO. And of course I get sway, 4lo, and cel lights. The hum remains *I think* but very hard to hear over all the other noises

 

With ignition in on, use a meter to test for voltage at the solenoid trigger wire, it should only have current flowing during starting. If no meter, can you reach it to disconnect it?

 

I think I'll have to disconnect it to check with the meter anyhow, let me check

 

If you unplug it and the hum stops, it has voltage

 

Voltage at solenoid in on position leads to relay or ignition switch issue. Test for voltage on start relay trigger wire/terminal when key in on position. This would indicate a bad ignition switch. If no current there, then the start relay is partially sticking in the closed or start position which indicates a bad relay.

 

Well, that was a fun exercise. Thank you for your help and patience, I learned several good things from this.
To answer the immediate question, no voltage on trigger wire.
But I did the smart thing I should have done before and disconnected the starter from the battery and the hum still exists with the ignition on. I think I was overly paranoid because of the burnt out starter I just replaced.

So, now I need to track down the actual source of the hum. Still just as audible as it was before.

 

Could it be the secondary air pumps that are humming?

 

Disconnect air injection pumps and turn on key

 

I would assume the SAIPs would only activate once the ignition starts as they're recirculating air from the exhaust back into the intake, and they usually sit on the driver side.

I would check the AC fan that's on that side of the firewall. ECU would probably be my last choice for it to go bad. Were there any other modifications done previously that you know of? I'm trying to think of what electronics sit on that side of the engine bay.