Another 4X4 problem!

Hey everyone! I am new to the forum and new to my 2008 Tacoma SR5 Double Cab V6 Auto and Hope to have 4x4 again! This is my first Toyota and have been a Ranger Owner since 2002. My last ranger which I have up for sale had 255,000 miles on it and still is one of the best truck on the road. I needed more room in the cab and I have been drooling over Tacomas for years. I do 95% of my own work on my truck and just want a reliable truck. I love my new tacoma!

Now the the question.... ANOTHER 4x4 problem... I have searched and searched and searched and I can not find any thing that sounds like what I have have going on.

Everything drives great and no warning lights of any kind. I switch the dial to 4hi and the light starts to blink and I can hear the rear actuator engage and when I am driving I can hear and feel a slight clunk but the light still blinks. Following all the proper steps and try to go to 4low the beeping starts. As soon as I flip back to 2hi the lights and sounds are gone.

I have tried going forward and back straight and turning the wheels and also try turning the 4hi while the truck is of and nothing changes. I crawled under the truck and I could feel and hear the rear actuator move and the front diff actuator beeped while the 4hi was trying to engaged !?! but there was not any movement or vibrations that tell me it moved.

Thanks for any Ideals?

Anyone have to mess with the two switches on the rear actuator?

Thanks
TacomaFishRig

 

In 2 hi stop the truck put in neutral then engage 4 hi put back into drive . See if that works.

 

this pertains to the diff actuator.

http://www.tacomaworld.com/forum/2nd-gen-tacomas/263525-how-trouble-shoot-4x4-actuator.html

I hope it is not your issue, but it very well could be. sometimes the front actuator can be troublesome. try it at varying speed, throttle on/off, turning, stopped, etc. I have found that if you try for 4lo without first having 4hi, it just results in trouble. not the best 4wd system ever, I miss my j-pattern and manual hubs

 

I tried the Neutral thing and nothing different. I am going to take the cover of the front diff actuator tonight and see what I can gain from that! I have read the front diff actuator post and it sound like that if the light always blinks even when in 2hi that it is the front actuator that has the problem. My does not blink unless I switch to 4hi. Maybe I am just missing something.

Thanks
TacomaFishRig

 

did you buy from private party or dealer?

if dealer have them fix it for free since the 4wd "function" is not operational

 

Private

 

So I just got done removing and soldering and reinstalling the front diff actuator. The inside of it was perfect! No sign of anything that should not be there. This was not that hard of a job. I used a 10" 3/8" extension and stepped that down to and 1/8" knuckle and then the socket and I got all four bolts out pretty easy and quick.

Topped up diff Fluid.

Bad News.... This did not fix my problem! Now the light on the dash blinks all the time!

If I take the actuator out again can I test the little motor but running leads to the main truck battery?

Any Thoughts?

Thanks

 

The ADD (Automatic disconnecting differential) is likely not working (vacuum line bad?). The ADD is what changes the free wheeling front hubs to being locked to the front driveshaft when you engage the transfer case. ADD replaced Automatic Locking Hubs, which required driving in reverse to unlock. The 4WD light goes from flashing to solid once you really are in 4WD. The same is true of the rear locker... flashing to solid when locked.

Normally, H2 to H4 is shift-on-the-fly up to 60 mph-ish.

Only going into and out of L4 requires stopping and shifting into NEUTRAL (not Park).

 

Isn't the ADD and the Actuator on the front diff the same thing?

 

The actuator is a part of the A.D.D system. But I would guess that the A.D.D system is acting up, There is a procedure for checking the movement of the actuator with a battery and a relay which will determine if the actuator is defect or not. You have to use a relay when checking the actuator because direct voltage applied will damage the unit. I'll try and find the procedure online for you and post it up.

 

When you request (funny how we have to ask for everything these days) 4WD, the computer first shifts the transfercase, then the ADD actuator.

You should be able to determine if the driveshaft is locked in at the transfercase just as you normally would if dealing with an all manual system.

Checking the actuator motors with a battery would be one thing to try, I'd imagine they don't like to be left on for a long period of time, so be careful.

There are electric motors in both actuators, and several sets of contacts serving as limit switches. The computer must be able to shift the transfercase, verify the shift actually took place, then shift the ADD, verify that the ADD engaged, only then will you be in 4WD with a steady green light. Any bad switch contact or a bad motor will cause a problem. If you stared at a wiring diagram long enough you could likely figure out how to test each limit switch contact, as well as the actual motors.

I don't know if a Toyota dealer would be able to use their scantool to pinpoint what is actually going on in there or not. Not sure if the 4WD computer communicates with the PCM/OBDII port. A standard code reader isn't going to help.

No vacuum going to the front diff on this truck, all electric.

 

Thanks for the additional info. I talked to a Toyota dealer today on the phone and he told me that it will probably one of the two switched on the rear t-case actuator. He also told me that if you test them with and ohm meter that they should not test over 1 ohm. If they do test higher then there bad. So I am not anything close to an electrician but I tried testing them and I the ohm meter jumps when I touch the prongs and then settles to back to 0. I am lost on this.

He also told me that you can jump the switches. I jumped them both and the read did nothing but then I jumped the front one the 4x4 light stayed solid and the 4low blinked.

With everything back together I can switch the truck to 4 hi when it is off and then start the truck and the rear t-case motor will lock in(I can't turn the front drive shaft with my hand) but to get it to disengage I have to turn the truck of and snitch the switch on the dash back to 2hi.

Still lost

 

4 Lo will blink if you don't put the tranny in NEUTRAL before turning the dial to L4. Not P Park, but N Neutral.

 

Well, you know the actuator motor on the t-case is working now.

Since the 4wd light is supposed to only go solid once the transfer and ADD have both shifted, it sounds like the transfercase actuator switches are bad. When you bypassed the switch and the light went solid, maybe the computer saw the transfercase engaged and shifted the ADD? Not sure about the 4LO light in that situation, but if you were jumping more than one switch at the same time, the computer could get confused.

If it were me in that situation, I would probably go with the voice of experience and change the transfercase actuator. OR, possibly try to take it apart and clean it? Not sure if that's even possible. I have never dug that deep into my Tacoma.

 

Joes06! You make a good point and until I read it, it wasn't apparent to me. If the light was solid then it shifted! GOOD NEWS. I am going to order the front transfer case switch on monday ($90 Dealer) I have not found these aftermarket.

Lets get 4 Hi and go for low later!

TacomaFishRig

 

Good luck! Good troubleshooting too!

 

Good News! So the light on my 4x4 was still flashing today and after work I drove for about 45 mins and I noticed that it had STOPPED!! So I click the switch to 4hi and it WORKED!! So I stopped on gravel and put it into neutral and switched to 4lo and it also WORKED!

Not sure why! I was thinking that maybe when I was messing with the switches and ADD that I set a code in the computer that finally reset with a certain amount of miles!

Hope it stays working!

Thanks for the help

TacomaFishRig

 

glad it worked out for you! keep us posted if anything comes up again

 

$90 is crazy for little ball on the stick. Not long ago those were $5. I should have bought a case and hold on to them. Better investemnt than stocks.