4wd won't engage

I have already tried swapping out the 4wd actuator on the front diff. It would work intermittently the first time I drove it, but now it won't engage at all. The actuator makes a sound like it is attempting to engage, but the light continues to blink. I am not sure where to look next other than maybe the transfer case actuator. It would be nice to have four wheel drive, if it ever decides to ever snow in Montana.

Thanks for your help

 

Start here and if this doesnt work for you , The link below this one is very good as well
https://www.tacomaworld.com/threads/transfer-case-transfer-cases-in-first-and-2nd-gen-trucks.345652/

Dm93 [OP]
https://www.tacomaworld.com/threads/4wd-system-operation-help-thread.742420/

 

The behavior you described does not seem out of normal. It will not shift if it doesn’t think it can without damaging the truck. Can you elaborate? Were you sitting still, moving forward in a straight line, other?

I find the 2hi-4hi transition is most reliable when moving forward at constant speed with minimal strain on the drivetrain.

 

*****In the original post I left out a crucial bit of info (now steps 1 and 2).****

This could easily be a bad 4-hi position sensor on the T case.
Shown here unplugged

Simple test:
1. Get all 4 wheels off the ground
2. Start the truck and and put it in 4wd. Does the front driveshaft turn????
If yes, you may have a bad 4-hi position sensor.

Now back to my original post.

3. Unplug wire from the sensor
4. Bypass the sensor using a wire or paper clip (looks like this)


5. Ignition on, then actuate the 4wd switch.
6. If you have 4wd, it's a bad sensor. If not, then good luck. This is the part (yeah I know it says reverse light, but it's the same switch. $15 to $20 at NAPA)

Note: With the switch bypassed, the 4wd light flashes all the time when in 2wd.

Have fun

 

I have tried it moving at various speeds and directions and while sitting still. I tried it today and it took anywhere from 5-10 minutes usually to engage going roughly 20-30 MPH on a dirt road.

Thanks dude, I will try this tonight.

 

5-10 minutes while driving down a dirt road seems highly unusual to me. I would expect a few seconds. I figured you were having a real issue since you were replacing parts, but your description of the issue didn’t cause me concern. CAVEAT: I thought I was replying to a 3rd gen post. The tap on my phone must have been inaccurate. . Unfortunately I have no advice to give you.

 

You could verify the switch at the 4WD ECU.
That’s what I’d do, because it’s easier than crawling under the truck.
And then if that is not it, you can check the rest right there while you are at it. No crawling under and unhooking anything.

If you want to know how to do this, see the link here (and above)
It will help save a lot of time.

https://www.tacomaworld.com/threads/4wd-system-operation-help-thread.742420/

 

Seems I'm finally having issues myself.

Going to 4 hi, I hear the tcase switch, but not the front diff. We know what that feels like, and it's not happening. The light even goes solid, but the steering doesn't feel heavy as it normally does in 4wd.

This stuff really needs to make itself known in the warmer weather!

 

Do you have 4Lo?
If the 4WD light is operating correctly, then all the limit/position switches are functioning.
If you have Lo range but no 4WD, then I’d suspect maybe the shift fork in the A.D.D Front Diff isn’t actually moving. I suppose it’s possible the gears are making contact, but the one with the limit switch is turning?

 

I get low gear in the tcase. Still no front diff locking up though.

I've got the 2 low mod installed. I'm going to disconnect it and see what happens before I climb under the truck.

 

Since you have the 2Lo mod I'm betting it's something with that, do you have it hooked up with an external switch or are you using the 4wd selector switch to activate it?

 

I don’t know anything about the 2Lo Mod.
Are you using the Mod Box that was for sale on the forum?
Or did you wire it yourself?

I need to take a look at how it actually functions.
But I haven’t really needed 2Lo, I need 4Hi for traction more than power.

 

When active it basically intercepts the signal to the ADD Actuator and through a series of relays and logic it simulates the correct limit switch voltages so the 4WD ECU "thinks' it's in 4wd when in reality the ADD isn't engaged.
The 2Lo module can be activated in 1 of 2 ways, it can be activated by turning the selector switch between 2h and 4h for a couple seconds or by changing the internal jumper an external switch can be used to activate it.

 

External switch. No it's not pushed. Lol

 

Interesting, it sounds like the 2Lo module is active when it shouldn't be, are you getting the light sequence for 2Lo?

 

I haven't read all the post but you take it swimming lately?

 

No light sequence

Nope, I haven't found swimmies for it yet.

 

I think I'd unplug your 2Lo module and see if your 4wd works normally, it sounds like yours is malfunctioning.
I have the same setup in mine with the 2Lo switch and haven't had any issues yet, I use mine pretty often.

 

That is the next step. Hopefully this afternoon I'll get it done.
Edit:
Managed to do it early. Disconnected the 2 low mod. No joy.

Oh joy. Not.

 

Sorry to hear that man.
I tell you what, some times I think I might be better off with a 2WD.

I mean, I’m pretty handy with a wrench an floor jack. 4WD to PreRummer swap.