I have a 95 Toyota 4runner. The 4 wheel drive has always worked however when I tried it about a week ago it took forever to engage. When I put it into H4 I can hear a click, kind of like a solenoid. It has the automatic hubs so you dont have to get out to engage them. Well there is a 4WD light that is suppose to come on, and it is not. Usually the manual says if you shift into 4wheel drive at a stand still the light will come on as soon as you start moving. Well I have shifted into H4 going 20, and have also shifted into H4 at a stop. The light doesn't come on, and the 4wheel drive doesn't work. Oh by the way L4 doesn't work either. Anybody have any ideas?
It is mechanically engaged with a lever. So I got underneath it and checked to see if the linkage was moving and it is moving. When I put it into 4WD the front drive shaft does turn, in 2WD it does not turn so I know it is activating in the transfer case. However mine is equipped with the automatic engagning hubs. So I am thinking this might be a problem. I took it down the street in L4, and the light came on, and it went into 4WD right away. Is there an electronic solenoid that engages the hubs automatically? Thanks for everthing.
There is a vacuum operated actuator on a clutch on the front axle. That is what engages the front wheel drive. It is controlled by the ADD relay. That relay is energized by a switch on the transfer case. There are some differences in the circuitry for stick and auto transmissions. I would check the ADD relay and the clutch actuator first.
Do you know where those are located? Is the switch activated by the lever and mechanical linkage on the transfer case? So how exactly does the front wheels engage into 4WD?
The ADD relay activates the vacuum-operated clutch, which engages the front axle for 4WD. One position of the relay activates the clutch to engage the 4WD, the other position disengages the clutch. The switch that energizes the ADD relay is mounted on the xfer case on my truck. There are two of them, one for 4WD and one for 4L. One is on each side, near thetop of the xfer case. I don't know where the ADD relay is. I have the same system on my T100, but it has not given me any trouble.
First of all thanks for all the helpful info. So the lever moves a linkage which engages the front driveshaft. From there a the front differential has to be engaged for 4wheel drive by vacuum. Perhaps I should check the switch to see if it is not positioned right. What trips the switch? I will check and figure out what I can, then let you know.
The 4WD light is switched by the 4WD switch and the ADD indicator switch (which I think is probably on the ADD clutch assembly. Since you said your worked in 4L, that says the fuse is ok. BTW, since you said everything worked ok in 4L, I would say your problem is the 4WD switch on the xfer case. The 4L switch parallels the 4WD switch; otherwise the circuit is the same (except that the 4L circuit also includes a path through the ECM).
I light came on, I am assuming by random chance. I had shifted from L4 to H4 several times before the light came on. Do you have a manual of sorts that provides all this info? I haven't been able to find a thing in the haynes manual. You keep mentioning a clutch. How does the clutch engage the front differential? I could find no switch on the xfer case. I did see a wire loom coming out of the same location were the linkage goes into the tranny. I also saw what looked like a plug with a wire attatched, but assumed it was some kind of temp sensor. Well I am at a loss, and really dont want to take it into a dealer. Is the switch I am looking for a limit switch? How does it change states, what causes it to change states?
The info came from the Toyota manual for my '94 T100. What looks like a temp sensor is probably the switch. The pix in the manual look like a plug with wires. It is activated by the movement of parts inside the xfer case. I haven't dug into the book to determine exactly how it works. Also, there should be another on the other side of the xfer case. One provides the 4L signal, the other the 4WD signal.
I think the term for the kind of clutch is "sprag". It is not a conventional clutch with a replacible disk. It is a couple of inches to the left of the differential housing. It does not really engage the differential. All it does is disengage the axle to one side. That effectively disengages your front wheel drive, because the differential does not not lock. Personally, I prefer the old fashioned hubs. They totally disengage the front end.
If you can find the nearest plug to the switch, you could disconnect it and check it with an ohmmeter when you move the 4WD lever in and out.
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