4wd problem - no light and movement from front diff actuator

hey all,

My first time posting on here. I have the push button 4wd selector. When I try to engage I hear the actuator on the transfer case move and the front drive shaft becomes engaged (don't turn freely when in gear) which is great because that's the expensive one. I took off the front actuator to see if the fork movement upon engagement/disengagement and it doesn't. I bought a new actuator and it still doesn't move. Furthermore, nothing happens with the dash light.

This system only has the one vacuum hose in the front actuator and is electronically mediated. Any ideas? I replaced the one fuse involved with the 4wd.

Thanks in advance.

 

Did you test for voltage at the front actuator ?
When you start the truck , do you have vaccum at the hose connected to the actuator ?
Wiring from the transfer case switch to the front actuuator switch can go bad .
Put the transfer case in 4x4 and test to see if you have voltage on the transfer case switch .
The transfer case switch sends 12 volts to the front actuator
Sometimes the trannsfer case switch goes bad and gets stuck in the 2 wheel drive position even though you have selected 4x4 .
Remove the switch and make sure its functioning properly mechanicaly .
The only time the dash light will illuminate is when the front diff actuator fork moves to the 4 wheel locked position
Go through the diagnostic list above and you will find your issue

 

The tube on the front actuator isn't for vacuum it's just for a breather.

 

Many thanks for this. I will give it a shot ASAP and let you know how it goes. Also I'm pretty sure I've read some stuff by you on throw out bearing that was insightful. Really appreciate the info.

 

Ok, so no luck. I have voltage to the transfer case switch as well as to the front actuator (actually about 10.5 V, and not the 12 V it should be. Is that an issue?) Still no luck with moving the front actuator though when I engage the 4wd. No vacuum from the hose, but as License2Ill says, i think it is just a breather.

Any other ideas? How does the switch actually operate? I see that it is on some sort of spring? Even though there is voltage at both points, somehow the signal is still not making it to the front actuator to engage.

Thanks.

 

Have you checked the vsv's?

 

Cory02taco,

I have an '04 tacoma and I don't believe it is vacuum operated. There is only 1 hose going into the front actuator and I think it is just a breather hose. Everything is electrically operated on this model (I believe...)

 

The transfer case switch is for continuity to ground for the 4wd ecu to see the position of the transfer case. It's either open or closed. Easy to test.
Edit: they're NO.


You also have a "Transfer 4wd position" switch that's also a continuity switch that the 4wd ecu needs to see the status of to operate the front actuator.

 

do you know where that is located?

 

Well that's annoying, Those are easy to fix. For some reason Toyota shows a few different diagrams of the front diff and associated hardware, including this pic, for the 2004 taco. I believe the switches for the transfer case are located towards the top of the case

 

According to the ewc. 4lo switch and the 4hi switch is on the driver's side of the TC.

Iirc they look similar. Blue connectors or grey. But wiring is of different colors. 4lo is gray & white-black line, 4hi is red wire with a blue line and also W-b wire.

 

Edit: I mixed up the wire colors. It's corrected now.

 

That's not an 04.

 

Probably not. But here's the info I put in the parts finder.

 

Thanks cory02taco, but I have a V6 manual transmission.

License2Ill, As far as I can tell, both those lines go into the same switch (which is new from the store and has 10.7 V running to it).

A potentially new development... When i try to engage 4wd-Lo, you can hear a clicking sound as if the system is grounding out or something is not connected well. Not sure if this means anything...

 

Gotcha. I did see a thread on here of someone taking apart the actuator and cleaning the contacts on the motor inside. Maybe that's worth looking into.

 

He said he put in a new front actuator.

 

Hmm. Interesting. So there's 4 wires coming from the 4lo switch? With two connectors?

And you positively verified the 4lo switch shows continuity to ground and the W-B wire(s)? when the shift lever is on 4wd?

If your 20a 4wd fuse is good. TC position switch is good. TC actuator is good and front actuator is good.
Then it's either the wiring/connectors or the 4wd ecu.

And like I said the TC switch is for continuity. You're seeing voltage there because it's plugged into a computer.

 

GOT IT!!! Something out of a comedy. I didn't catch that the washer from the old switch was caked in place and when I put the new one on I effectively had 2 washing and the spacing was too far for the switch to work. Unreal. Thank you for your help everyone!!

 

I was of no help, but I'm glad you got it working.