4 Wheel Drive Not Working

I searched for this problem. If I missed a resolution somewhere, I apologize in advance. Here's the deal:

Every once in a while, my 06 Tacoma (V6 / Auto Trans) will not go into 4wd. It has the switch, not a shifter. If I turn the truck off, switch the key all the way on (without cranking the truck), then switch it into 4wd and start it, it engages the 4wd every time.

I am not familiar enough with what happens when I flip the switch to diagnose the problem although I do hear a clicking under the glove box when the 4wd light flashes.

I was thinking maybe that "part" that is clicking (sounds like a blinker relay) may be going bad, but I do not know what that "part" is.

And then SOMETIMES, it switches into 4wd, on the fly, just fine - as it has since I got it.

Any suggestions on what to replace first are welcomed.

Thanks.

-JM

 

Heard the switch dies if not used often. Dirt on the contacts.

 

Thank. I use it 2-3 times / month. I don't THINK that's what it is. Plus, if you turn the truck off, turn the ignition to ON, then switch to 4wd and start the truck, it works. Very weird.

I will clean the contacts on the switch.

Any other ideas?

 

But that would indicate a voltage drop when running. no ? Poor contact ?
Make sure everything is nice and tight. Check also the connections on the 4 wheel drive ECU behind the glove box too. You could also climb under and check the limit switch and shift assist on the transfer case.

I have no clue what is wrong but at least it's a place to start.

 

Thanks again, Trap. I am going to check the switch itself as you suggested. Like you said, its a good place to start.

In the mean time, if anyone has had this problem, your input would be greatly appreciated.

-JM

 

Check the wires that go to the solenoid on the front diff there is a plug there to check as well. The wires are run through metal hangers that if loose will wear through. The info Trap gave you is a good place to start.
This will help as well

 

Heard the solenoids are junk on the transfer cases. Might have to replace it.

 

First question would be whats the mileage on the truck and when did you replace oil in transfer case and front diff ??

 

Thanks, North.

The links are great. According to the wiring diagram:

When the 4WD control switch is turned from H2 into H4, this signal is input into 4WD control ECU TERMINAL 2–4). Then, the 4WD control ECU moves the 2–4 select motor (TERMINAL 2, TERMINAL 1) in the transfer shift actuator assembly until the shift fork shaft shifts to the diff. free position, performing a shift into H4 position

If the ECU is indeed behind the glove, then this makes me think Trap was right from the get-go and that the actual switch is bad. I don't think my signal is making it to the ECU...

I will pop that switch out and inspect / clean it.

Anyone ever pulled a switch? Pitfalls? Tips?

Thanks.

-JM​

 

100K miles on the truck. Transfer case and diff oil was replaced at 30K and 60K.

BUT, even if the tranfer case and front diff were full of swamp water, they both work just fine (I drove it in 4 hi and 4 low 2 hours ago). The running gear of the 4 wheel drive system works just fine. It's the system that tells the truck to GO into 4wd that's acting up.

This seems to be a signal (electrical) problem, not a mechanical one.

But thanks.

-JM

 

Look at the thread to light up the 4 wheel drive switch Mod. It shows how to get it apart.

Sometimes you can do more damage than good trying to fix a switch but I'll give you this tip. A silver conductive pen can save you. If the contacts are worn cause of lots of use you can build them back up with the pen. Let dry well. Or if a trace looks iffy same you can repair it with the pen.
http://www.tacomaworld.com/forum/technical-chat/3681-diy-gen-2-illuminated-4wd-switch.html

 

Well, it's $56.82 for a new 4wd switch from Toyota. With the no return policy on electronics, and the fact that I am not positive that this is the problem, I think I'll find someone close that will let me "borrow" theirs for testing purposes...

-JM

 

I had my actuator go bad in my 2006. Toyota replaced in under warranty. The light would flash and not engage. Not sure if this helps.

 

UPDATE: Went to Toyota dealer for free car wash, oil change and pedal recall mod. I asked them to check the 4wd and tell me what was wrong. Answer verbatim = "Uh...It's probably the switch".

I find it hilarious that they didn't know either. Anyway, I have ordered the switch and when I replace it, I will let ya'll know if that was the problem.

Thanks.

-JM

 

I know this is a old thread, but was the switch the problem...........just came back from trail, truck would not go into 4 hi or 4 low, no dash indicators or nothing. I was wondering if it was the switch or something else. HELP

 

yeah, did that and started a search on TW....thought could be the switch since everything looked good on tc..removed and disconnected, blew on it a few times, reconnected and BAM......... good as new. TACOMAWORLD...............FTW.

 

I know my post is old but...


I replaced the switch and no change.


So, I am still where I was when I started this post:

• The truck will go into 4WD just fine the key is in the "off" position, I turn the 4WD switch to 2H and then start the truck.
• MOST of the time it will NOT go into 4WD when the truck is running (no flashing light, no NOTHING).

I called the dealer and asked about the 4WD "ECU" behind the glove box and the parts guy told me he has NEVER sold one. Of course, that doesn't mean mine isn't shot, but I thought I would pose the question to you guys one more time before I start just parts changing.


Any ideas where to start???


Any help would be appreciated.


-JM

 

Update:

I went to the dealer today for the Airbag Recall fix. That went well and they even washed my nasty truck.

HOWEVER, they claim that the front differential actuator is bad and that is why I am having this problem.

I'm not sure I'm convinced.

It seems like if it was the actuator, then it would not go into 4 wheel even if I turn the truck off, switch it to 4 wheel and then start the truck. But, as stated above, that works every time. Plus, after seaching the forums, everyone with a bad actuator complains of a blinking 4WD light. I do not have that problem.

So, next question: Can the front differential actuator cause my truck's symptoms? If so, HOW?

Thanks.

 

Pull apart the ADD actuator and see if the contacts need to be cleaned and re-soldered:

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

 

Yes I've had the same problem, twice now. Those front diff actuators are junk

Save the money and change it yourself. It's a 20 minute job and the part is available online much cheaper than a dealership will sell it for