[5 Speed]

Here is a link

Front Differential Actuator Repair / Replacement - Toyota FJ Cruiser Forum

Not the link I used but close enough, I changed my ADD out 3 years ago. I chipped a tooth in mine.

Thanks Stormtroopers, I did find and read this link before I took it apart and I was hoping my part would have looked like the one in the thread but it is totally different. I was hoping that I could solder up the two tabs but there wasn't two tabs and it had a very different motor design. Basically the worm drive shaft was directly connected to the coils that make up the motor and I guess somewhere inside the plastic cover is where the wires to the brushes were. Should have take a photo of it. I hope opening it up and putting it back together somehow made those internal brushes make more contact and that is why it is working now. I didn't re-grease anything because it looked pretty clean but do you think I should open it back up and do anything?

 

[Stormtroopers]

5 speed, I took these photos for you. Note that the ADD actuator in the photos is good.



In the cap there are 5 fingers that follow the contacts as the gear turns. Make sure that all of the contact points are shiny and level with each other. The grease is there to keep the contacts from corroding.

DON'T TAKE THIS APART UNLESS YOU HAVE TO!
There are two contacts that are under spring pressure, if you pull out the motor they will fall out. Getting them back into their spot is tricky. This photo is after cleaning.



Here is the worm drive motor, cleaning up the contacts with 600 grit wet/dry sand paper. There may be a way to sand up the contacts with out removing the motor.

 

[chamjam]

Thanks for the info Guys. I'm waiting for the Haynes manual I ordered before I jump into those repairs, so i don't make the my problem worse!
Steve

 

[5 Speed]

I don't think you can really do anything wrong if you remove the whole actuator but I just removed the outer cover and basically put it back together and it works. Unplug the actuator and remove the vacuum hose then the 4 phillips head screws and the cover is off. I think basically moving the large gear inside a few degrees side to side and putting it back together got it working again. I did remove the small motor cover but don't see any benefit to doing this and getting the small ball bearing back inside the cover was a pain. If you remove the whole actuator I think you will probably loose a little gear oil. Be sure to clean the mounting surface if you replace the whole unit so the sealant keeps it leak free when you reattach it.

 

[5 Speed]

Well it worked for about 30 or so cycles and then quit. I crawled under and removed the outer housing with a large screwdriver and this time I took a nail file and smoothed the ends of all the contact fingers. Some of the tips had slightly rough ends like there might have been some slight current arching. Then I moved my finger around all the contact surfaces inside the cap and found a rough spot and smoothed it down with a nail file. My theory is that when the fingers and surfaces aren't smooth there isn't perfect contact and this slight drop in current somehow shuts it down. Put everything back together and it is working again. Where I was in Montana over the Holidays required 4x4 to get up to the house and down every time because of the snow and ice. I can get it apart and back together in about 10 minutes.

 

[2kTundra]

Thanks for all of the info and links on how to fix the problem. I just want to post my experience in the chance that it may help someone at some point. I preemptively apologize for not giving exact names of the gears, pieces, etc. I'm not a mechanic.

So my 4hi light started blinking a long time ago and the old trick of knocking on the transfer case actuator worked for a while but it only lasted so long. Last Saturday I decided to try and tackle the problem. I started by removing the plastic motor portion of the transfer case actuator and pulled both pieces out and cleaned all of the old dried up dielectric grease out and then lubed up the contact area with some new grease. Putting it back together was a little tricky as the long gear would not seat into the sprocket/gear that sits back inside the housing. I had to remove the whole actuator from the transfer case and open up the little plate in the back to pull the sprocket/gear out so that the long gear could go in, then slide the sprocket/gear over the teeth of the long gear. I also cut off a small piece of the rubber vacuum hose prior to putting it back on the nipple since it had signs of cracking. After I put everything back together I tested it out. I could now hear the actuator working on the transfer case but was still getting the dreaded 4hi flashing light.

Next I tried tapping on the front differential actuator (ADD) to no avail. I then tried removing the four large screws on the plastic portion of the ADD; unfortunately they would not budge, even with liberal amounts of PB Blaster applied to them and waiting for several hours to let it soak in. Not wanting to strip the screws, I decided to go ahead and remove the entire actuator from the axle. This proved to be challenging given the minimal amount of clearance provided for the top two 12mm bolts. I was eventually able to remove them with a socket and a small extension; they were on there pretty tight as well so I had to put a small home fab'd breaker bar on the end of the socket wrench to break them free. In order to get the whole unit out, I removed the rubber hose portion of the power steering line on the passenger side of the axle. Just be aware that once you remove the whole ADD, diff oil will start coming out so have a container ready if you didn't already drain the diff. Also, power steering fluid will start coming out once that rubber hose portion of the power steering line is removed as well so have another container ready for that. I could still not get the old unit apart without stripping the screws even after I pulled it out and figured with all the work it takes to do this it was worth buying a new factory part and hope for another 10+ years out of it.

When I started to mount the new part to the axle, the shift fork was in the opposite position of the original one and would not mount to the sleeve that engages the hubs. I eventually hooked it up to the vacuum line and the wire harness and turned the ignition on without the motor on which caused the fork to slide over into the spot it should be. From there I was able to get it into place and mount it to the axle pretty easy. I then started the motor and gave it a shot; luckily it all worked. I've been trying it daily and it hasn't failed yet. The only other challenge I had was trying to get the differential oil into the differential since there isn't much clearance there either. I debated taking it to a oil and lube shop and just paying to get it drained and filled but eventually I was able to cram the bottle up in the space and get it filled up.

Here's my cost break down as well:
Front differential actuator ( ADD ): $366 from dealership (O'reileys had an off brand for $222)
Toyota FIPG: $14 from dealership
1L Lucas diff grease: $14 at O'reiley's
1qt Power Steering fluid: $5
Set of allen wrench sockets for front diff fill/drain plugs: $14 (I bought the set to have but I believe you only need a 10mm)

 

[exMM3]

My 01 DC would have the flashing 4HI/2HI light on the button flashing problem. Mine would happen when trying to DISengage from 4HI. I tried everything to get it disengaged... Neutral, circles, turn left, right, kicked it twice, and finally I gunned it HARD in reverse and heard an awful THUD and it disengaged.

My problem happened to be that both of my front drive axles had very bad cv play, and needed to be replaced. I replaced both front axles and yesterday I engaged and Disengaged 4HI, 12 times, flawlessly in the mud. Also, I never exercised my electric actuators as one should, and from now on I will, because I really don't want to play with those things.

 

[bclemente]

Well I'm having the same issue. Didn't use the 4 wheel drive for the past 6 months and when I pushed the 4Hi button, all I get is flashing light and NO 4 wheel drive. Followed the suggestions on this thread to no avail. There are distinct sounds of the actuators trying to engage / disengage when the buttons is engaged / disengaged.
Is there anything else to check or bang with a hammer!!!!! GRRRRR!
Thanks
Steve

Have you solved this problem? My 04 tundra double cab is doing the same thing, can hear the motor disengage and engage but the light still blinks. I also don't have any 4lo light at all.

 

[Woodchucker]

I have a 2004 Tundra. The Hi 4WD and Lo 4WD works perfectly when I start the truck. After I've driven 8 miles at highway speed, it refuses to engage Hi 4WD. Does anyone have a suggestion as to why this is happening?

 

[Shane1962]

Last night I was working in a field and turned on my 2001 Toyota Tundra's 4 WD.
Immediately both the Hi and Low 4 WD buttons began flashing as well as the display.
I had no idea what was happened so I called a friend and he suggested disconnecting the battery terminal waiting 10 min & reconnecting. To make a long story short it continued flashing. This morning I called a transmission shop and spoke to the owner about what was happening. He said its the actuator motor just did one last week its common will cost $1000 for the motor and $500 labor for a total of about $1500. I then googled the question and joined discussion. I then printed out everyone's response and called another mechanic bringing your comments with me. The mechanic was receptive to this discussion. He tested the power and continuity of the actuator and plugs. He then told me to push the Hi and Low 4 WD button while he lightly tapped on the actuator with a hammer. Within 5-10 taps there was the old engaged sound and the light went out. The mechanic then told me lack of use. Make sure you drive at least 10 miles per month in 4 WD to keep everything working properly. He then told me to do the same with the air conditioner in winter and the heater in summer. Run them for 10 minutes a month or so. Thank you everyone. You ARE the greatest. Had I not come across your discussion I probably would have gone with the first mechanic's suggestion. THANK YOU !!!!!!!!!!!!!!!!!!

 

[Darrylthenewf]

My 2004 Tundra starting flashing its 4wd light in the dash. So I took off the actuator on the transfer case and found corrosion and rust on the electric connectors. And water still in it. I cleaned it up but had no time to try the 4wd. So I drove it for a day and the light starting blinking again. Now the question is where do I find the front actuator? Pics would help a lot here peeps

Thanks in advance

 

[AmyTundra]

Hello, I need help with my 2002 Tundra TRD 4wd. I cannot get it into 4wd - my dash buttons feel great to use, but no light ever comes on. I can tell by the way the truck drives that it is not engaging 4wd - I had hoped it was a bad bulb. I tried at least 25 times over a couple of weeks. I took it to my favorite local independent shop, who did lots of troubleshooting but did not identify the problem. Here's what they put on my service ticket:
"Checked fuse and relays - all ok. Checked control switch - it has power to it, but will not turn on (it is not flashing either). Checked for power and grounds - OK. Removed and checked the control computer - it has no burn marks and pins were tight. Recommend dealer for further diagnosis."

Before I take it to the Stealer, any advice or education you can share with me? It was working a few months ago. I've learned through reading here that I should use it monthly.
Thank you,
Amy

 

[AmyTundra]

Update: I took it to the dealer, and was told that a switch replacement was needed, "integrated control panel 4wd switch assembly" part number 8953334010. When I search for this part, I find it as COMPUTER, 4 WHEEL DRIVE CONTROL. Looks like internet pricing for the part alone is $312 - $440. My total out the door should be just under $600. That seems okay for a Stealer diagnosis, parts, and labor. Wish me luck once the part comes in and the service is completed!

 

[Checkmate Marine]

Old thread but needs a bump. I have an 04 Tundra SR5 manual trans that the 4wd and ABS stopped working. Actually, ABS wasn't working, found out the 4wd wasn't working after that. Found that the 4WD will not activate if the ABS does not work.

Scoured the wiring diagram, no ABS codes, changed ABS module ($125.00 wasted), checked ABS sensors, all seems good but still no ABS. Figured the best thing is to bypass ABS to make 4WD work. No info anywhere.

BUT! All is not lost as I have figured a better work around than one previously posted.

Going through the wiring diagram, I found that the motor to activate the 4WD was a simple 2 wire setup. Connected to the tranny control module, it was connected wit ha red/black wire on one side and a red wire on the other. By throwing Positive and negative into the 2 wires (first one way, then the other), I was able to activate the ADD and lock the axles. No dash light (yet) but definitely 4 hi and lo.

For me, this is a no brainer. The 4WD activates when I shift the tranny into 4 Hi or Lo as it is controlled by the floor shifter. I simply wire a 5 amp fuse inline with the tranny module disconnected and I'm done. For an automatic tranny, I would imaging the same can be accomplished by cutting the ADD motor wires out of the TCM and wiring them to a switch on the dash. Leave the rest of it alone and plugged in (mine is no longer connected, benefits of stick vs automatic) so it will not interfere with the rest of the electronics.

If interested, I've added the wiring diagram for an 05 Tundra. The wiring is SIMILAR to an 04 so use it with caution for whatever year yours is. I believe it is supposed to cover 04-06 but.....

Any questions feel free to ask. I am a marine electrician and am used to these issues. Hope this helps someone else.