Been having some issues with the 4x4 not working on my 99 4Runner. The light would just blink, and I had no noises or engagement of the front axle.
After some inspection, I found that if I tapped on the AWD actuator, it would work a few times, but eventually stop again. Jumpering the motor directly would not make it run, and the motor did not sound very good when it did run. So I decided to dig in and fix it. Here's what I found, these actuators are not cheap new, and it's getting harder to find good used ones.
There are a total of four ball detent type switches in the system that need to be working for it to operate. Two on the AWD actuator itself (these are the 2wd/4wd shift indicators), one up high on the transfer case (low range switch) and one more on the front diff that closes when the front axle disconnect engages. From what I understand these are common failures, it would be smart to check them before you dive into the actuator.
The mechanical shifter only locks the center diff, and the H/L/N positions. the actual 4x4 shift that couples the front and rear driveshaft is done by the transfer case actuator.
Here's how you remove the actuator.
1. Undo the three electrical connectors on the actuator, and the vent hose.
2. Remove the three 8mm screws from the triangle shaped cover near the top of the actuator, remove the cover. Access is pretty limited unless you remove the driveshaft, but an 8mm wrench will work.
3. Remove the three 12mm bolts that hold the actuator to the transfer case.
4. Underneath the triangle cover, is a small gear that connects the shift rod of the transfer case to the worm gear. Grab some curved long nose pliers and pull it out. You can wiggle/rotate the whole actuator since the bolts are out as needed.
5. Once the gear is out, you can slide the actuator rearward and remove it.
Once you have it on the bench, here's how to disassemble it.
1. Remove the three 10mm bolts from the round cover on the side of the actuator. Remove cover. This will reveal the contacts for the limit switch mechanism. You may find that they are corroded or dirty, mine were fine. There are more contact "fingers" on the backside of the cover that should be cleaned. Then you can remove the worm gear simply by pulling it out.
2. Remove the three Phillips head screws from the motor housing. Pull it off.
What you are going to see is just a brushed, DC motor. Pretty simple. In my case, I found that the field magnets had broken free and were jamming the armature. Some 5 minute epoxy took care of that. Orientation of the magnets does matter, as each pair of magnets will have opposing polarity, the motor will not run if they are out of phase.
The worm gear has a spring dampener on the back side of it. Unless it is broken or has an obvious issue, I don't recommend taking it apart as it looks quite difficult to assemble. The purpose of it is to allow the actuator to shift the transfer case with spring pressure, rather than a direct coupling.
Polish up the brushes and the commutator if your motor needs it. Mine looked great. You can use a pick or toothpick to stuff the springs back in the brush holders, then put the brush in and loop the lead around the housing to hold them. Drop the armature in (there is a single ball bearing on each end, make sure they're in the right place), and unloop the brush leads. Get some new grease in the bushings, and drop the motor cover back on.
If you wish to bench test the motor, do it now, before you drop the worm gear in. It should run smoothly in both directions. Mine did.
Follow this video on how to time time the worm gear when you install it. It does matter, and do not run the motor once you install it. This is in the 4x4 position.
https://www.youtube.com/watch?v=zXGxijCAIUA&t=10s
From there, all you have to do is install the worm gear cover.
This is where I ran into some difficulty. The actuator and the transfer case need to be synced for the system to work. It took me a couple of tries.
As I mentioned the actuator is in the 4x4 position. To put the transfer case in 4x4, wrap a rag around the shift rod and push it all the way forward. You may need to rotate the shafts slightly to get it to shift all the way. Now you have both the actuator and the transfer case in the same position, and you can install it on the vehicle.
The only tricky part to installing it is the little gear that connects the actuator drive and the transfer case shift rod. I found it easiest to slide the actuator all the way on, leave the bolts out, and then slide the gear on, wiggling the actuator until everything lined up. It's important to not let the actuator slide away from the TC during this process.
After that just grease the gears, install the triangle cover (with a little sealant), and bolt the actuator on. Once I had everything timed right, the 4x4 and AWD have been working perfectly, and I saved about $400.
I found this thread to be helpful, the E-locker actuator is very similar, and he found the same problem with the field magnets coming loose.
E-locker motor issue: Diagnosis and fix!
After some inspection, I found that if I tapped on the AWD actuator, it would work a few times, but eventually stop again. Jumpering the motor directly would not make it run, and the motor did not sound very good when it did run. So I decided to dig in and fix it. Here's what I found, these actuators are not cheap new, and it's getting harder to find good used ones.
There are a total of four ball detent type switches in the system that need to be working for it to operate. Two on the AWD actuator itself (these are the 2wd/4wd shift indicators), one up high on the transfer case (low range switch) and one more on the front diff that closes when the front axle disconnect engages. From what I understand these are common failures, it would be smart to check them before you dive into the actuator.
The mechanical shifter only locks the center diff, and the H/L/N positions. the actual 4x4 shift that couples the front and rear driveshaft is done by the transfer case actuator.
Here's how you remove the actuator.
1. Undo the three electrical connectors on the actuator, and the vent hose.
2. Remove the three 8mm screws from the triangle shaped cover near the top of the actuator, remove the cover. Access is pretty limited unless you remove the driveshaft, but an 8mm wrench will work.
3. Remove the three 12mm bolts that hold the actuator to the transfer case.
4. Underneath the triangle cover, is a small gear that connects the shift rod of the transfer case to the worm gear. Grab some curved long nose pliers and pull it out. You can wiggle/rotate the whole actuator since the bolts are out as needed.
5. Once the gear is out, you can slide the actuator rearward and remove it.
Once you have it on the bench, here's how to disassemble it.
1. Remove the three 10mm bolts from the round cover on the side of the actuator. Remove cover. This will reveal the contacts for the limit switch mechanism. You may find that they are corroded or dirty, mine were fine. There are more contact "fingers" on the backside of the cover that should be cleaned. Then you can remove the worm gear simply by pulling it out.
2. Remove the three Phillips head screws from the motor housing. Pull it off.
What you are going to see is just a brushed, DC motor. Pretty simple. In my case, I found that the field magnets had broken free and were jamming the armature. Some 5 minute epoxy took care of that. Orientation of the magnets does matter, as each pair of magnets will have opposing polarity, the motor will not run if they are out of phase.
The worm gear has a spring dampener on the back side of it. Unless it is broken or has an obvious issue, I don't recommend taking it apart as it looks quite difficult to assemble. The purpose of it is to allow the actuator to shift the transfer case with spring pressure, rather than a direct coupling.
Polish up the brushes and the commutator if your motor needs it. Mine looked great. You can use a pick or toothpick to stuff the springs back in the brush holders, then put the brush in and loop the lead around the housing to hold them. Drop the armature in (there is a single ball bearing on each end, make sure they're in the right place), and unloop the brush leads. Get some new grease in the bushings, and drop the motor cover back on.
If you wish to bench test the motor, do it now, before you drop the worm gear in. It should run smoothly in both directions. Mine did.
Follow this video on how to time time the worm gear when you install it. It does matter, and do not run the motor once you install it. This is in the 4x4 position.
https://www.youtube.com/watch?v=zXGxijCAIUA&t=10s
From there, all you have to do is install the worm gear cover.
This is where I ran into some difficulty. The actuator and the transfer case need to be synced for the system to work. It took me a couple of tries.
As I mentioned the actuator is in the 4x4 position. To put the transfer case in 4x4, wrap a rag around the shift rod and push it all the way forward. You may need to rotate the shafts slightly to get it to shift all the way. Now you have both the actuator and the transfer case in the same position, and you can install it on the vehicle.
The only tricky part to installing it is the little gear that connects the actuator drive and the transfer case shift rod. I found it easiest to slide the actuator all the way on, leave the bolts out, and then slide the gear on, wiggling the actuator until everything lined up. It's important to not let the actuator slide away from the TC during this process.
After that just grease the gears, install the triangle cover (with a little sealant), and bolt the actuator on. Once I had everything timed right, the 4x4 and AWD have been working perfectly, and I saved about $400.
I found this thread to be helpful, the E-locker actuator is very similar, and he found the same problem with the field magnets coming loose.
E-locker motor issue: Diagnosis and fix!
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