4WD wont engage and NO light comes on

Well I would contact the former owner and asked if it worked and when was the last time he used it.

Then purchase a digital VOM and a set of short insulated jumper wires 1 black , 1 red. Then on your truck you can clip the black jumper wire to a ground and the other end to the black lead of the meter. Practice using it until you get used to seeing 12.6345 volts or 12.6 volts when your on the DC scale. The AC is used for power in your house. Most get confused AC or DC, MA and Amps, just stay on DC Volts for now.

I would verify power to the switch before anything else. Some car circuits may be at logic level 5 vdc if they are hooked to a computer, if the plug has Yellow it might be for the Air Bag circuit. A diagram would really help you, but power to the switch is pretty basic.

You said when you turn the switch to H4 the red 4WD light comes on??? Is that true?

 

Any other dash lights on? Also since it's new to you, might as well change out the t-case and both diff fluids. Who knows when it was last done. Would also eliminate any worries of broken stuff.

 

The PDF posted by whatstcp is what you need, excellent. For petes sake don't get involved in changing fluids ? until you get it working!!

 

I've seen weirder things. Some systems (not saying this does) wont turn on without fluid in it. I just know from experience that checking your fluids is #1 when buying a new vehicle, especially sight unseen.
Just my 2 cents. I watched someone throw 2 cylinders because he didn't check fluids after buying a used truck.

 

Check them, sure. But if there's fluid it's ok not to change them yet.

I would open up your stereo again and really inspect it fiercely. There may even be another fuse associated with actuating the 4WD, so get out your manual or find on the forum a list of what all the fuses do.

 

If you turn your truck off and engage the 4wd and then turn the truck on does it actuate?

https://www.tacomaworld.com/threads/4-wheel-drive-light-wont-come-on.359501/

 

there is only one, and if it’s blown, it will cause the lights to continuously blink (4x4, 4lo)

 

I almost thought this happened to me last night, light was flashing constantly and wouldn't engage. Finally it went in. Y'all are scaring me.

 

Shhhhh. Don’t talk about it.

 

I'd check the actuator plugs under the truck for corrosion then if that's not it, pull the actuator out and check for movement.
https://www.tacomaworld.com/threads/how-to-remove-transfer-shift-actuator.509650/

https://www.tacomaworld.com/threads/4x4-issues-front-diff-actuator-or-t-case-actuator.358059/page-3



Or you could just Marlin swap it.

 

And I have a different problem 4x4 engages but no light

 

That sounds like the bulb in your dash went out. Replace the bulb and check back.

 

Did ya ever get it working? I'm having same issue, no light, no 4x4, no actuator noise.. also seems to.be no power to switch.

 

Have you checked your 4WD Fuse (20A) in the interior fuse box left of the steering column?

If that's good check for power and ground at the 4wd ECU with the key on.
https://www.tacomaworld.com/threads/4wd-system-operation-help-thread.742420/