2004 TRD Manual Trans. can't shift into 4H

I have the button on the shift knob "shift on the fly" to get into 4H and it is not working. I can shift into 4 low no problem, manually shifting the lever forward in and out but the Green 4WD indicator light does not come on, even as I creep along in 4 Low. Checked the fuse and it's ok.
I did periodically shift into 4H just to keep the parts moving once in a while as I rarely am off road but I do use it more frequently in winter.
Bad button? Never did like the "automatic" shift, my Dad's '85 Land Cruiser was 100% manual with 100% less crap to break.
Scratching my head.

 

Is the 2004 a vacuum or electronic operated 4wd? It maybe something a bad connection somewhere under the hood (can be cleaned withe electonic cleaner spray). On my 2000, I sometimes intentionally prevent the front axle from engaging by unplugging the electric signal going to the vacuum switch so I can get 2lo when backing up my trailer (manual trans....comes in handy).

There could also be a bad fuse sonewhere. I'd start there if you haven't already.

Or maybe the green 4wd indicator light bulb is out. Put it in 4hi or 4lo and have someone safely look under the vehicle to see if the front drives shaft is spinning while the tires spin.

 

So 4lo works even though the light on the dash doesn't come on at all? Are you sure 4hi isn't working either? It's not always easy to tell if 4hi is working, not like it is with 4lo anyway. Maybe it's just the LED light on the dash that went out or got disconnected somehow. Usually if 4wd isn't working then the light will blink at you

 

I did check the fuse and it's good. I believe the 4WD button is electrically operated. There's no mistaking being in 4 low, going 2 mph at 3000 rpm is first gear so I know that's working. When I'm in 4 high I can feel the front drive gears buck a little and I need to give more throttle with the steering wheel all the way over and that is not happening now so I'm pretty sure it's not engaged.

 

Sounds similar to the issue I'm dealing with. Symptoms are basically the same.
When you put the lever into 4LO, you're probably not in 4WD but rather 2WD low gearing. That lever is the transfer case. And that is entirely mechanical. So you can't push that lever forward and not be in low gear.
Both your transfer case actuator and A.D.D actuator on the front diff should both be electronic since you've a 2004. It's easy to check, just look for plugs.

If you've already checked relevant fuses and relays, the next step would be to take a multimeter to the plugs. You should be able to find the correct readings online. If not, I will look through my stuff and see if I can find them. If they check out, my first guess would be what I am 99% sure my issue is and am working towards fixing now. That'd be the ADD actuator.

But do me these things to help verify a few things so I can see that it is indeed just like my issue.
-unplug the plug on the t-case actuator. See if the 4x4 light blinks, indicating an issue (mine does this)
-plug it back in
-unplug the ADD actuator and check the 4x4 light again (mine does not blink for this one)
-keep it unplugged
-start the truck and press the 4WD button in the cab. Can you now hear the t-case actuator function? (mine does this)
-plug ADD actuator back in for safe keeping

If your results for the above steps match mine, there is a good chance your issue is the same as mine, which is most likely the ADD actuator.

 

Interesting. I'm not familiar with where the plugs are located, can you tell me where to look? I'm not that advanced as far as mechanical ability but I can do basic stuff (like change the O2 sensor...until I realize the pipe is rotten and the muffler has a hole in it, then I took it to the shop. I can't do exhaust) Thanks for the help! If I can't do the repair the next best thing is being armed with the knowledge of what's wrong exactly.

 

Got some schooling within this thread that may help you on your journey . The thread deals with

$90 2005-2015 Toyota Tacoma With 4L Right Petrol intake air snorkel kit high performance system compatible kit Replacement black Rotational Molding (2005-2015)

2005-2015 trucks but the 4x4 system functions the same https://www.tacomaworld.com/threads...er-case-in-the-2nd-gen-truck-write-up.345652/

 

I'm no tech myself. I learn what I need as I go along. And this site is a godsend.

The plugs are right on the actuators, which are on their relevant parts. I'll post some pictures.
The transfer case is here. And the black thing with a plug is the actuator. This is looking from underneath the driver's side door.


The automatic disconnecting differential (ADD) one is a little harder to see. This is is in the middle of the truck directly beneath the front of the transmission.

 

Hmm some good info in here. I've seen your thread before. It does look slightly different, the parts, but should work basically the same. It looks much more open in the front, at least in the pictures. Not sure how much is involved with getting the old one out and new one in on 1st gens. I've been looking into that recently. I fear there's quite a lot.

 

Thanks so much, yeah this site is a godsend. I'll check the plugs when I get a chance.

 

If it isn't the actuator, it could be the transfer case switch. I had the same exact issue and a new transfer case switch fixed it for me. Dorman 600-554 is the part, ~$40 at any shop.

 

So, for shits and giggles last week I press the transfer button and voila! It shifts into 4WD, dash indicator light is on, turn the steering wheel hard over and feel the resistance of the front drive train. What's up? I'm glad it's working but it's pretty weird.
I notice that while in 4WD the drive train seems stiffer than before, meaning while turning hard the resistance is greater, "stickier" if you will.
This is an '04 with 105k miles, my manual says to replace transfer case oil at 115k miles but most trucks this age passed 105k years ago. could it be that the increased resistance in the front differential is due to old oil? Could that have caused the the issue with shifting into 4WD?
In the past week I've shifted into 4WD many times with no issue and shifted out without issue. It should be noted that the first few times I shifted out there was a loud and noticeable clunk but last several times I heard/felt nothing.

 

Everything is all lubed up again .
They say to use 4X4 at least once a month on a dirt road to keep parts lubed . Maybe thats all it needed . If you still have the owners manual with your truck , there should be some literature in there telling you to take it for a rip in 4X4 occasionally .
This reminds me that I need to run my truck in 4x4 . Havnt used 4x4 much over the summer

 

^ what he said. It sort of "use it or lose it".

Well regardless of why it's working, I'm glad to hear it. If you haven't changed the fluids in the truck yet, I suggest doing it ASAP. Along with a lot of other maintenance, I recently did mine. Both diffs, trans, and t-case. None of them had ever been done, and my truck just hit 173K. Whether or not that had anything to do with my 4x4 not working, I will never know, but it certainly couldn't have helped.