UPDATE: see post #11 (reply #10) below: https://www.toyota-4runner.org/3688745-post11.html

2000 SR-5 auto with J-shifter 4WD. My 4WD HI and LO worked normally (correctly) before the frame swap.

Current Situation:
- My front wheels are not getting power when I shift into 4WD (HI and LO) (no binding or wheel chirp on pavement).
- I do hear the actuator click
- I do see the 4WD dash light illuminate at the appropriate time.
- I do shift into the low gears (slow moving, high revving) when in 4LO.

Things I've already checked:
- The front propellor shaft spins freely while in 2WD.
- The front propellor shaft locks up and does not spin freely while in 4HI and 4LO.
- The frontmost VSV hose has vacuum while in 2WD.
- The rearmost VSV hose has vacuum while in 4HI and 4LO.
- Switching the VSV hoses prevents the 4WD light from illuminating at all (and does not send power to the front wheels), suggesting the hoses are currently in the correct places.

Question:
What's my next step in troubleshooting this?

New cv axles go in soon, the truck will be up on a lift. Thanks!!

Sounds like your tcase is doing what it needs to do but maybe not the ADD system. The fact that the front driveshaft is locking up when in 4HI or 4LO suggests this. Since you have an open diff if the ADD doesn't kick on then it will just send the power to the disconnected stub shaft.

Since the front driveshaft is locking/unlocking then your transfer case is operating as designed.
Your VSV and relay are working correctly since vacuum is switching.
I would check the vacuum lines from the VSV to the ADD actuator. Some people have had disconnected/broken/damaged vacuum lines causing the ADD actuator to not move/engage. If you have a hand vacuum pump (Amazon.com: Mityvac MV8000 Professional Single Person Manual Brake and Clutch Bleeding Tune-up Kit : Automotive) you can also actuate the ADD system yourself to make sure the actuator is functioning properly.

If the dash light is illuminating then the actuator in the front diff is working. How are you determining you are not getting power in the front? Sounds like something mechanical in the front diff if it is indeed not working.

Unless the wires are shorted - which can happen from mechanical damage during engine/frame/body installs. The front indicator switch is on its own little harness that can be missed and/or damaged.

-Charlie

Thanks for the replies. I'll update when I figure it out.

Looks like my 4WD (blue) ADD solenoid is bad.

Toyota still sells PN 8544035040 which is the whole assembly. Pretty pricey.
Some sources show this part is no longer in production (but dealers seem to still have stock).
Neither NAPA nor RockAuto have anything for this PN.

EDIT: I found Toyota PN 8544035040 used for a decent price. Used OEM with a one-year warranty. I'll update this thread to confirm fix.

Has anyone rebuilt one of these ADD solenoids? (I've watch @mtbtim 's video on rebuilding the starter solenoid.)

The ability to rebuild these would be pretty useful since according to some sources they are no longer in production. Based on my searches, they really don't seem to fail that often, but still.

(Toyota dealers still have these in stock, but I didn't see any new OEM PN 8544035040 for less than about $530).

I know you can also bypass the ADD system: Toyota Tech: Defeating the ADD System

When/If my ADD dies, I'm going to defeat it, and just bite the bullet on the Tacoma Manual Hub conversion.

This is my thoughts as well

SOLVED

Just updating this thread to confirm that replacing the “Solenoid Assembly, Four Wheel Drive Control” (Toyota PN 8544035040) fixed my issue. Even though it was only the 4WD-specific (blue) ADD solenoid that failed, I replaced the whole assembly with a used one that was pulled from a '99 Tacoma.

I kept my old assembly so I can attempt to rebuild the bad solenoid and keep it as a spare.

FYI the official Toyota Parts website and a few other sources say that Toyota PN 8544035040 is no longer in production. About a month ago a few dealers had some in stock for $550-$750, but that new-old-stock now seems to be gone. I paid Japanese Truck Dismantling about $134 for my used Tacoma assembly (which they had cleaned and tested and shipped with a one-year warranty). I also saw a couple assemblies and a couple solenoid-only listings on eBay at various condition levels and price points. What I'm saying is that Toyota PN 8544035040 will only get more difficult to find as the years go by.

If I can successfully rebuild my old unit, I'll document the process in a new thread.

Thank you everyone for all the help!

glad you fixed your issue.
about 2 years back I pulled all the solenoids and everything related including the actuator on the axle... at a pick and pull....now sitting on my shelf if needed.
so guys as cl4Rk pointed out these are getting expensive new if you can find them. so if your in a pick and pull and find them you might want to grab and store it for the future.

thanks for that link

I'm a bit confused how you were hearing the actuator and how your dash light was illuminating if your VSV was bad.

I am too, honestly.

I thought the actuator would only click if it was getting the correct vacuum.

And I thought that the 4WD dash indicator light would only turn on if the front differential was reporting back that everything was engaged properly. Given my situation, I'd expect to get no light, or maybe a flashing light. IDK.

Maybe someone here can elaborate?