Brique
New member
Ok, so there are already a ton of "OMG my 4wd won't work" threads out there already, I'm writing to add some observations that I haven't seen in any of them yet. If it's out there and I missed it, sorry.
tl;dr: before you get under the truck and start fooling with the sensor and actuator, try giving the system a few extra minutes to get it into 4wd. Successive attempts may take even less time, until the problem eventually works itself out.
I bought my 4runner (2001 SR5 Sport, push-button multimode 4wd, auto transmission) 3 months ago and noticed shortly after I bought it that the 4wd wouldn't properly engage. The dash indicator light would keep flashing, indicating that there was a problem engaging. After some trial and error in a parking lot, I was able to finally get the system to turn off after completely shutting the truck off, removing the key and starting again. I read the existing material on this and other forums, and the consensus was that the problem is usually a bad sensor (more often) or a bad actuator (less often) or sometimes a bad vacuum line. Anyway, I made note of the likely culprits and resolved to leave the 4wd alone until I was in a position to do something about it if the next time I tried it I was unable to get it to disengage.
This afternoon I was getting ready to change the fluid in my front differential and took the truck for a drive to get it up to temperature. Figuring "what the hell", I decided to engage the 4wd for a bit to get the front diff going in preparation for the oil swap. I found a relatively straight stretch of road and hit the 4wd switch. As before, the indicator blinked and blinked but wouldn't engage. I left it on for a bit and this is where it gets cool.
I continued driving down the road with my fingertips on the shifter. After 2-3 minutes, I felt the thump of the actuator kicking in and the indicator light went solid. Awesome! So I tried it again. Again, the indicator blinked, but this time it only took about a minute for the 4wd to engage. Rinse repeat, every time I engaged/disengaged it took a little less time for the switch to occur, until eventually it got to the point where it was nearly instantaneous! YAY!
Center diff lock was a similar story, except that it's much more stubborn. Engaging the center lock made steady improvement, but disengaging proved more difficult. I found a trick here to help it along. Driving on that relatively straight stretch of road (approx 30-35mph), I found that once the indicator starts blinking, let off the gas, then give the gas a little push, where you can feel a thunk in the drive train. That little thunk seems to shake things to where it can disengage. It's not back at instant like the 4wd is, but it seems to be improving.
So anyway, I found that although I was prepared to start fooling with the sensors and actuators to troubleshoot the system, I was pleasantly surprised to find that giving the system some time to work itself back into shape worked in my case.
tl;dr: before you get under the truck and start fooling with the sensor and actuator, try giving the system a few extra minutes to get it into 4wd. Successive attempts may take even less time, until the problem eventually works itself out.
I bought my 4runner (2001 SR5 Sport, push-button multimode 4wd, auto transmission) 3 months ago and noticed shortly after I bought it that the 4wd wouldn't properly engage. The dash indicator light would keep flashing, indicating that there was a problem engaging. After some trial and error in a parking lot, I was able to finally get the system to turn off after completely shutting the truck off, removing the key and starting again. I read the existing material on this and other forums, and the consensus was that the problem is usually a bad sensor (more often) or a bad actuator (less often) or sometimes a bad vacuum line. Anyway, I made note of the likely culprits and resolved to leave the 4wd alone until I was in a position to do something about it if the next time I tried it I was unable to get it to disengage.
This afternoon I was getting ready to change the fluid in my front differential and took the truck for a drive to get it up to temperature. Figuring "what the hell", I decided to engage the 4wd for a bit to get the front diff going in preparation for the oil swap. I found a relatively straight stretch of road and hit the 4wd switch. As before, the indicator blinked and blinked but wouldn't engage. I left it on for a bit and this is where it gets cool.
I continued driving down the road with my fingertips on the shifter. After 2-3 minutes, I felt the thump of the actuator kicking in and the indicator light went solid. Awesome! So I tried it again. Again, the indicator blinked, but this time it only took about a minute for the 4wd to engage. Rinse repeat, every time I engaged/disengaged it took a little less time for the switch to occur, until eventually it got to the point where it was nearly instantaneous! YAY!
Center diff lock was a similar story, except that it's much more stubborn. Engaging the center lock made steady improvement, but disengaging proved more difficult. I found a trick here to help it along. Driving on that relatively straight stretch of road (approx 30-35mph), I found that once the indicator starts blinking, let off the gas, then give the gas a little push, where you can feel a thunk in the drive train. That little thunk seems to shake things to where it can disengage. It's not back at instant like the 4wd is, but it seems to be improving.
So anyway, I found that although I was prepared to start fooling with the sensors and actuators to troubleshoot the system, I was pleasantly surprised to find that giving the system some time to work itself back into shape worked in my case.
