How To Trouble Shoot 4x4 Actuator

Good news on the scanning front though!! Was it a scan at the dealership? Is there any corresponding codes? I’d happily pay an hrs rate to dial in where the issue would be coming from.

To remove the tcase actuator you have to split the transfer case... there are 2 “E” clips retaining the shift fork in the tcase. Without that all you can do it’s take the cover off which exposed the motor and worm gear/crown which mates to a coil type driver (this helps prevent stripping the gear teeth), etc.

The 4lo switch I BELIEVE is the rear switch (closes to ass of truck) of the actuator. There is a difference in plug type between the 4hi and 4lo, there’s a tank that protrudes between the Connection prongs on the 4hi and not on the 4 lo so you can’t mix up the connections from harness, so make sure you get the right one.

There is but isnt... 4hi and 4lo each have a push type limit switch that operate off an indent in the "rack type" shaft of the tcase actuator that slides to engage 4hi or 4lo. the transfer case actuator setup os basically a worm gear off the motor that runs a crown gear, that crown gear rotates a pinion gear on a mating assembly that slides the shaft the gear selecting forks are on.

On the front ADD, on the crown gear are contacts that slide on arch type connections that are moulded into the plastic housing, depending on the contact of these connections determines the open or closed circuit of whatever is connected by the tabs on the crown gear, if that makes sense. look on page 3 of that wiring diagram and 9in the blud ADD box, on the far right, youll see what i mean. thats the only 2wd "switch" that i can figure within the system, the other way i believe the system confirms that it is not in 2wd is that it relays back the signal to say its in 4wd...

What do you mean the actuator beeps? theres no way for the front diff to produce a sound, itd come from the 4x4 module..


I may try to order that switch... im wondering (if for whatever reason) that the switch i got from Auto Value was opposite to what should be in there meaning that instead of normally open, its a normally closed? sucks because it was a f%cking 100$ switch... but who knows. actually maybe ill pull the switch from the wrecker i got the 4x4 dash switch from and 4x4 module... (which i still need to plug in and test, should have done that tonight)...

I swear, once i figure this out, im building a master trouble shooting break down type up from the gods for diagnosing what the issue is...

 

I mean it literally makes a beeping sound in the actuator.... very low sound and beeps about every second or so .... I didn’t think that was possible either but no doubt about it .... I cycled the 4x4 the same way with an aftermarket actuator and that doesn’t beep but same issue with not disengaging front diff .... I finally got a official wiring diagram and will be checking continuity next . Will post pics of diagram

 

Could i get a copy of that PDF to troubleshoot please? My 4x has not worked in years... finally stumbled on to this Forum last year and am amazed what can be done at home and not at the stealerships....

 

Went ahead and pulled the front diff actuator last night, it basically looked brand new inside once I got everything apart, I didn't think it was the issue. Either way soldered everything together put it back in and 4x4 is now engaging. I did end up breaking one of the screws on the acctuator and I couldnt get it out, came up with a temp fix, hopefully it will stay together for a while, I may end up ordering a new one just to be safe. Either way appreciate this forum.

 

So the scanner was a unit that my bro in law has at the BMW dealership. It’s able to run all codes but it’s more BMW specific. It would not let him reset any of the fault codes that were being thrown in my 4wd system.

I ordered a cheap sensor on eBay to see if maybe that would fix the issue.

As far as the transfer case actuator goes I may dig into that tomorrow and see what I find. I’ll report back after wards

 

I'm not sure what codes you think you will get from a scanner. The 4wd computer does not talk to the ECM. A multi meter is all that's needed to troubleshoot.

 

Wasn’t giving codes, it was telling us what sensors were functioning and which ones were not. Well the scanner was able to pull data from the vehicle from the ODB port so......

 

Which one did you get and what year truck you have? Maybe they change the way the 4wd ECU is connected, on mine (2010) the 4wd computer is a standalone ECU and does not talk to the CAN bus or have connections to the ECM.

 

I concur with this, the 4x4 module is a separate entity and does not provide any diag codes to the scanners in regards to the procedure or status of things... unfortunately this requires an old school approach with a meter, patience and some beer haha.

On this topic. I further insight as to troubleshooting procedure for this ordeal.

https://www.customtacos.com/tech.ol...toyewd/06toypdf/ewd/2006/tacoma/h/em01d28.pdf
Open this in a separate page...
look on page 3, youll find DL1 and DL2 wires. Using a small solid core wire plugged into the socket of the master plug for these two, you can do a continuity test to determine if they are open or closed through the chassis. ground on the door hinge, and red on the wire for the solid green DL1. There SHOULD be continuity in 2wd and 4wd...
the pink and blue DL2 should ONLY have continuity in 4wd, NOT in 2wd. in my case i do have continuity in 2wd which tells me my front actuator is not disengaging which correlates with the 4x4 light flashing that it hasnt completed its 2wd move. remember these systems are closed looped systems meaning there is an Action (turn to 4hi from 2hi) - *4x light flash* request to act (4x4 module confirms its not in 4hi) - *4x light flash* makes action (initiates actuators) - *4x light flash* (front actuator first - completed action recieved by computer based of switch limits) - *4x light flash* 4x4 module confirm (shifts transfer case) - *4x light flash* confirm Tcase switch based off 2 4hi and 4lo switches on actuator shaft - * 4x light stays on* 4x4 module sees all limit switch signals required to justify completion - 4hi completely engaged and 4x4 light is on.

my next step now is to replace the front actuator... i want to dig into mine to determine what is what with it, i have already had it out, and rebuilt it and tested it all and it worked on the bench but didnt seem to be once it got back in... but based of eletrical testing its the actuator body itself. 250$ shipped is ok. id rather have one ready to put it when i pull this one out, than be dicking with the broken one, only to have to put a new one in anyways... this way i can dig into the old one to determine WHY it fails so often as they seem to.

following that i will be dedicating some time to putting up a full troubleshooting guide on determining the issues within the 4x4 system that anyone has, no it wont be bullet proof but itll have the links and step by step information to get these things sorted in the easiest and most direct methods... ill be ordering the actuator this week and installing it once its not -40deg here in calgary haha...

updates to follow!!!

 

Nice work on the troubleshooting! You have the order of operations backwards though. First the transfer case engages, then once in 4hi, the 4hi limit switch on the transfer case sends a signal to shift the front actuator. DL1 and DL2 control how far the motor moves by removing the ground from the motor once the limit is reached. Once the system is in 4wd (transfer case and actuator) there is a 3rd limit switch (light green/black wire) called ADD, that then signals the 4x4 ECU to turn the 4x4 light on solid.

 

Woo. My truck now cycles into 4wd.

And stayed in 4wd. I gave up trying to fix it. Off to JH Garage it goes - I want it done right for the next owner.

 

Sub

 

Just wanted to say thanks for the insight on this thread. I was having the ADD issue as well and tried the soldering technique but seems the motor didn't have enough power to engage. I then ordered a new part from Amazon ($150 w/prime) and put it in this weekend. As I swapped it out I got 4H and 4L intermittently when I tested afterwards. I topped her off with oil and now she is engaging every time. To note she did take in more oil than what was released when removing the ADD.

I think my symptoms were a combination of a weak ADD motor and being low on lubrication. Thanks again for the information!

 

Sounds like you might want to do an oil change in the front diff and T-case. FYI the front diff takes 1.6 qts and the T-case takes 1.1 qts. Oil level should be right at the bottom of the fill plug when the right amount has been added

 

Thats awesome man!
I got my front actuator the other day, too cold atm here in alberta to change it out haha but looking forward to it. This gives me hope hahaha

I'll be typing up a fairly easy and direct trouble shooting guide to this that anyone with a Voltmeter can do. This will happen once I change out my actuator and prove that that is in fact the case.

 

My 4wd/4Lo light comes on intermittently. Which obviously doesnt alow me to engage 4x4. Which is unnerving this time of the year in PA. I greased up connections at transfer case.

When the lights come on and i shut the truck off and turn it back on, it will sometimes go away.

Should I try the motor solder fix in the front diff??
Or could the issue be at the transfer case??

I don’t even know where to start

 

Bump for any help

 

When you move the switch from 2wd to 4wd, do you hear the transfer case doing anything

 

No. But today when I got home i put it in 4hi to get up snow covered driveway (long) and the 4x4 light kept flashing as in not engaged yet but it actually did engage.

 

Oh lord...

Did you try switching it back to 2wd yet