[denlion81]

Hi everyone,

I would like to share my story of how I fixed "typical 4WD" issue of 3rd gen T4R. Hopefully it may help someone in a similar case. The beginning of this story is very simple: I was going to wheel with O4WD club, checked that 4WD worked the evening before and... it simply stopped working next morning when I tried to push the button before entering the trail. I couldn’t complete even the easiest trail that day and was very dissappointed and angry...

So, I started to educate myself on the issue, reading websites, articles, forums. Found out about ADD and vacuum actuator. Visually checked vacuum lines under the car and realized that the small metal tube on the vacuum actuator was rusted out and could be easily removed by hand. I decided that this was my issue (totally wrong!), and followed these steps suggested on one of the forums:

1. Start from ignition is OFF and 4WD disengaged.
2. Get down under the car and try to move short (front) driveshaft. It moves free - that is how it should be in 2WD.
3. Take out rubber hoses from both VSV and start the engine - vacuum should appear in one of those hoses.
4. Push 4WD button - the vacuum should change hoses on working system. [In my case it was still on the same hose, so my 4WD ECU doesn't give a command to switch it. Noted.]
5. Cross-switch the vacuum hoses, ADD is engaged, light is on. So, that concludes that ADD is working. The driveshaft should NOT be moving free as well. It means that the passenger side of the axle is connected now.

I concluded that ADD system and all vacuum-related stuff worked well. Even with the vacuum hose barely pulled on tube, since the bigger part of it was rusted and fell off. I kept searching and on one European forum devoted to TLC, someone shared with me the wiring diagram for Hilux/Sulf/T4R VZN185. I came up with the algorithm to check wiring and 4WD ECU:

1. Opened the drives side panel and found that 4WD ECU, took out the plug from it.
2. Ignition is ON, plug is out from 4WD ECU, started "check-ups" on wiring/pins: check that there is positive 12V on #16 and negative on #8.
3. Check that there is negative 12V on #15 when 4WD button is pushed and not otherwise.
4. Ignition is ON, plug is IN 4WD ECU, but it is out of the box, so I can "check" how it works (really careful, don't create short-circuit on a plate).
5. Check that after 4WD is pushed ON, there is a 12V between #2 and #3 for sometime (command to actuator).
6. Ignition is OFF, plug is out of 4WD ECU and just check circuit between #2 and #3 on the plug site. It is there.
7. Stop right here, since there is a signal, there is circuit through the actuator motor, but the actuator isn't moving (you can hear when it works), which means the actuator is fried (

So, I tried to buy a used actuator on a scrap yard / ebay and found the description on how to replace it. There is a post from me on this (and some others) forum about interchangeability of the part # 36410-35040 (which I already had) and the part # 36410-35051 (that I could buy). No one could confirm if these parts were indeed the same, but on that European forum I came upon an experienced and reputable member, who had done several rebuilds on these actuators. He gave me some good advice and I decided to give it a try.

Honestly, taking out the actuator is quite simple - there are three bolts (socket #12) keeping it attached to TC, and you will need to open the "big front cover" (three bolts, socket #10) also. The last step is to take out the "big gear" with metal switches on it. Just notice and remember the position of that gear, in relation to the marker on the actuator case. If your 4WD switch is OFF and 4WD is disconnected, you will see that the first big metal track is perfectly aligned with that marker. After you take out the big gear you can remove the actuator from TC. Also, I personally advise to open the small triangle cover on the actuator (three bolts, socket #10) and remove the small cylindrical gear which should be loose after you removed the big one.

When I opened the motor cover I could see the issue right away. Exactly what I was told on the forum by that guy - loose magnets. They are the most common issue on those motors. They just leave their designated places and all move together, so the motor stops working. The fix is very easy, to be honest - you just need to glue them all back together and remember that the magnets which repulse each other
need to be on the opposite sides. I realized that it took precisely 4 wooden matches to fill in the space between neighbour magnets, and decided to add them as spacers. It takes about 24 hours for Gorilla Glue to be fully cured.

So, next evening I removed the residue of glue, cleaned everything and put everything back as it was, using dielectric grease. Here is the hint: before putting the motor cover back, insert the "big gear" in its place, otherwise the magnets from the cover will pull up the rotor and you’d have to start again. I learned that hard way To put the actuator back, I followed this algorithm:

1. Remove all gears from the actuator, put your TC in a "4WD disenaged" position, put the actuator on TC, connect all wires.
2. Put the "big gear" in its place, aligning the first metal switch with the marker (as you noted it before).
3. Ignition is ON, press the 4WD button. You should hear "humming" and the big gear should turn to the "locked" position.
4. Carefully, without moving the "big gear", take the actuator out from TC.
5. Using your hands, put TC in the "4WD engaged" position. Just push 4WD rod in.
6. Put the actuator back on TC. Connect all wires, tighten all bolts.
7. Now the "small gear" can be installed and the small triangle cover can be closed.

So, everything is back to its working state now. No "timing" it or any other magic required. I have done a small (15-20km) ride switching it on and off. Really eager to try wheeling ASAP again. And yes... special thanks to @badluck user who wished me a "Good Luck" on my rebuild.

PS: The rebuild cost me about 40CAD: 30CAD for set of O-ring, to replace the old one under the motor cover, and 10CAD for Gorilla Glue. Just a reminder: there are at least three different types of this actuator, and my description relates only to T4R 1996 LTD, VZN185, transmission A340F, actuator part #: 36410-35040

Here are some WIP pics (hopefully they will load this time):

[Toy2play]

Very nice job, great write-up. This will come in handy for someone down the road.

[denlion81]

Originally Posted by Toy2play

Very nice job, great write-up. This will come in handy for someone down the road.

I hope so!

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