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Ted Ritter
Ted Ritter, Toyota Master Tech
Category: Toyota
Satisfied Customers: 4449
Experience:  Toyota Master Tech, ASE Certified
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The four wheel drive on our Toyota T100 will not initiate.

Customer Question

The four wheel drive on our Toyota T100 will not initiate. We just had the tires rotated last week, could this be the cause? The gear will go in but it doesn't actually iniate the four wheel drive.
Submitted: 8 years ago.
Category: Toyota
Expert:  Ted Ritter replied 8 years ago.
Does the 4x4 indicator light on the dash light up when put into 4x4 hi/lo?
Customer: replied 8 years ago.
No the light does not come on,XXXXXis not engaging.
Expert:  Ted Ritter replied 8 years ago.
The front differential has a vacuum operated actuator attached to it which engages the front differential, the switch that turns the dash light on is mounted on the differential. The problem is with the actuator, check to make sure the vacuum hoses are attched at both the actuator and the vacuum switching valve on the right side under the hood on the fender. It's also possible and very likely that the vacuum ports on the actuator are clogged, try cleaning the ports with stiff wire. If that doesn't work the actuator should be removed and tested by applying vacuum to the ports, the shift fork should move when doing this, if the shift fork can't be moved by applying vacuum then the diaghragm is leaking and the actuator should be replaced.
Customer: replied 8 years ago.
We cannot see anything that looks like the vacum hose. We pulled off the dirt guard and looked under it also and still did not see it. By right side I'm assuming that you are referring to the passenger side? Can you guide us as to what the actual hoses look like or ore specifics on their placement.
Expert:  Ted Ritter replied 8 years ago.
Did you locate the actuator on the front differential? It's just to the left(driver's side) of the differential housing, the indicator switch is actually located on it. There are two small vacuum hoses attached to the actuator, follow these hose up under the hood on the passenger side fender are a few switching, two of them relate to the actuator, make sure the hoses are connected to the switching valves. You can see the hoses come up from below, they are about 5/16" in diameter.
Customer: replied 8 years ago.
We can't seem to find the hoses at all. Is there an online diagram we can locate? Or is it possible that both hoses would have fallen off completely. It has been a couple of months since we used the four wheel drive.
Expert:  Ted Ritter replied 8 years ago.
OK, you did find the actuator right?
The actuator has two metal pipes about 1/8" in diameter coming out of it, these are the pipes that I mentioned earlier that can get clogged up, the hoses should be attached to these pipes. I have a factory diagram of the system but it's in PDF format and I can't attach that type of file here, I can try to convert to a format that this forum will accept but it may take a little while. I guess it's possible that the hoses fell off or were removed, check the solenoids on the inner fender to see if there are any pipes that have no hoses on them.
Customer: replied 8 years ago.
Could you email the drawing to me [email protected]? Thank you for your help.
Expert:  Ted Ritter replied 8 years ago.
<img src="/uploads/toyotatech/2009-08-24_170228_Add_Control_System-1.jpg" alt="graphic" width="2241" height="3294" />