4 x 4 flashing; switch does nothing; but i can jumper it??

Good afternoon all, my name is Faron, i have owned my 2011 Tundra for 5 years now and I am having a similar issue to others whereby the 4x4 light flashes and the 4x4 switch will not engage the front diff.
Background:
Initially, the problem started and it was temperamental, sometimes working and other times not... Eventually it just stopped working all together. The 4x4 light flashed as well as the VSC light would come on; cruise control also stopped working. I did some research on Youtube and in other forums and checked for problems in the hi/lo actuator on the transfer case, everything there seemed to test out fine. I removed the front diff actuator and found the vacuum line (vent line) was broken off at the housing and upon further inspection it was apparent it had been invaded by moisture as the armature inside was rusty and not moving freely. I rebuilt the actuator tested and reinstalled it and I still was unable to have any success. Having mounted the truck on stands, I engaged the drive line and jumped the 6-7 pin on the transfer case actuator with +/- current to see if the front diff would engage and voila! the front diff engaged (actuator working!) I then reversed the current flow to reset the drive line back to 2 wheel drive. After the front diff actuator repair, doing a battery reset to clear memory and codes had the effect of removing the VSC transaction control dash light, also upon road testing, I now have my cruise control operational. Sadly I am still not able to get the 4x4 light to stop blinking and moving the switch either way has no affect at all. I took it to a Toyota dealer but the service center there was just an oil change and light service bay. The gentlemen there put his level 3 code reader on it and reset some error codes. The codes did not come up again, but again, no resolve to my problem. Given we have already had 1 large snowfall this year, i'd better get it resolved, does anyone have any ideas? I am short on budget and feel like it could be a astronomical service bill if I take it in to another Toyota dealer. Given that I've had some success repairing that front diff actuator, I wonder if there is something simpler that I am missing here? Any help would be appreciated.

 

Put a meter on the actuator connector and see if it's getting voltage. If not, start chasing wires back to the switch. Check fuses too. Be aware that the voltage may be present when the actuator is unplugged, because there's no load on the circuit. If you can, measure the voltage with it plugged in.

 

Try switching the brake stroke sensor. It can cause the light to come on and persist, at least that's what my mechanic friend has seen on Tundras, including mine.

 

As a side note, I forgot to mention that when I turn on the am radio I can here a power frequency distortion through the radio...kind of a series of shorts beeps and then a long one (then it repeats) I'm wondering if there is a grounding issue somewhere? I'll see if I can get a measure on that voltage, seems to me I did try measuring voltage on the connector with the ignition on and got nothing...but i have been away at work so haven't crawled under the truck in 3 weeks now.

 

Kerch71, curious, did your indicator just flash or was the 4x4 also not engaging?

 

Sorry just for clarification.... You turn the 4x4 switch and nothing happens? No sounds, no engagement, nothing?

 

As for voltage, it will only be there for a second until the actuator stops moving. Watch this video, it's very good at showing exactly how the Tundra works. https://www.youtube.com/watch?v=47m7QAPrpsI

 

That was a very nice video.

 

Tundy White , that's correct...

 

Good video. That fact that I'm able to jumper it into 4x4 by applying power to the transfer case electric motor shift actuator, tells me there is no power getting to it when the 4x4 dial is turned or during ignition. It would seem the mechanics of the system are working properly after i had repaired the ADD actuator though. Damn I wish I had a lift or a pit to work under, tracing those line could be a real pain in the ass. I wonder if it could be the switch itself?

 

The switch has two diodes in it. So in 2wd, only the black wire is grounded. In 4HI, both wires are grounded. In 4LO, only the yellow wire is grounded. A bad ground, bad switch contact or bad diode could screw that up. If that isn't it, it could be an ECU problem. Check the 3 fuses in the diagram.

 

Here's the whole wiring diagram for your truck.

 

Thanks avt077, I've got some homework to do by the looks of it!

 

Any luck with this problem? I've got the 4Hi flash and no ADD engagement...was thinking of pulling it to have a look. Did you have any problem with clearance while removing the ADD? Looks like there's only an inch or so of space to pull it out.

 

Hey, I know is thread is 3 plus years old ,but I've got the same issue. Did you ever get it figured out? Thx

 

Ok first time here. So I have a 2011 5.7L crew max. Today the 4lo was flashing at me so I tried to exercise it a little to make it work. Now let me preface by saying that since I got the truck it has always had a problem with the 4lo flashing. So I barely use it. 4hi works great. But during everyday 2wd operation I can sometimes hear what sounds like gears trying to engage even after it is in gear. Also, when I’m driving between 20-60 there is a noticeable vibration which I’ve read is either the drive shaft not balanced, a vacuum leak, or the torque converter is going bad. To me it felt like maybe the teeth weren’t alined or maybe broken. But anyway, trying to get it into 4lo, After 8 or 9 attempts, it worked! But then I couldn’t get out of it. So doing some homework I found videos on the transfer case actuator. Found several videos, watched them all. Took the thing apart. Moved rods to the “neutral” position for both upper and lower rods. The lower one was difficult and the upper one was already in. So when I got the lower one in I thought I heard an odd noise. So I hope I didn’t screw it up. When I opened them up I found that the lower actuator seemed to be missing a contact switch like the ones in the videos. But it only had one pin that could have been used and it did not look like the other had been broken off or anything. Also didn’t look like anything had been soldered to the pin either. The upper one had 2 pins and the switch was soldered to them. Of course I lost the damn tiny lever for a while but I found it. Cleaned it all up, added new dielectric grease. Put everything back together and go to test drive it. The truck will not move. it will not shift into any gear. But when I go to put it in park, it grinds the gears until it stops. I disassembled the front differential disengage control actuator thing and found that, I should have had an oil pan ready, and the 4wd was still engaged. So after freaking out and swimming in oil now cause I accidentally pushed the ring too far to the right and cannot get it back on the spline. Finally I got some picks and pulling from the top side I was able to get it back on. So by lifting the front of the truck I was able to turn the front drive shaft and unlock the 4wd. This should have put it into 2wd and now maybe the truck can move. No dice. So when I ran my cheap as scan tool it only came up with P0500 A2 which is a VSS sensor. It could be the abs wheel sensor, or the transmission position sensor, the output line sensor or the wiring harness under the intake manifold or maybe my battery need to be charged up. Who knows. At this point I’m ready to just saw it in half with my chain saw. Can anyone shed some light here? Did I royally mess it up or was this going to happen anyway? What should I do?

 

I have the exact same problem except I am able to use the cruise control. The actuator switch on the dashboard will activate the differential occasionally but not on demand. I did put a code reader on it awhile back and it pointed at the differential switch being the problem but short of just swapping it out with another I’m wondering if anybody found a different solution?