4lo light flashing

I was on a gravel road today and thought it was a good opportunity to put the truck in 4 low just to exercise that once in a while (as I thought it would probably be bad to never use that). So I put the truck in neutral and switch the truck from 2wd to 4h to 4l. The truck successfully transitioned into 4l based on the 4 low light turning into a solid color. It only turned into the solid color after I put it in drive and drove it forward for a few yards. I then drove it for the next 30 yards or so and stopped the vehicle and put it in neutral to attempt to put it back to 2 wheel drive. But now the 4 low light is just flashing, and I think the truck is currently stuck in 4 high, as I have been able to drive it at normal speeds, e.g. 40 to 60 mph and the RPM is between normal ranges, e.g. 1k to 2k. If it was actually still in 4 low, then I don't think I would be able to drive it at this speed at the RPM levels I saw. I'm pretty confident that its in 4 high because when I do a tight turn on gravel I can hear the tire skid, also if I go in reverse with the wheel turned all the way on pavement I can feel the binding starting to occur.

I've done some light research, and have tried disconnecting the battery and reconnecting it, and hitting the transfer case and the transfer case actuator to no avail.

This is a used truck with almost 300k miles that I only recently bought. So I don't know if the transfer case oil was changed anytime recent. I actually recently placed an order transfer case oil and differential oil, and those are currently being shipped.

At this point, what am I supposed to do? Drive it to autozone to have them do a scan to see if there is a code? The check engine light isn't on by the way.

 

bump, also I've scheduled an appointment with a mechanic to have this looked at next week, but am still interested to hear about what might be causing this.

 

Take a closer look at the shifting instruction for 4wd on the drivers side visor

You need to engage 4hi first before 4low. Then shift to n from 4hi from 4low. Then in reverse order to disengage. 4hi shifts while driving. Never shift from 2wd to 4low.

 

I did use the instructions from the visor. I basically did the procedure as shown in this video: https://www.youtube.com/watch?v=bhrtdgCrnvs

I had no issue going to 4 lo, and don't need guidance regarding how to do that.

I'm having issues with the 4 lo light blinking currently, and am interested in learning how to diagnose the issue.

 

Are there any other lights on or flashing? Have you had it in 4Lo before? Do you have Techstream by chance? If you have Techstream I would look to see if you have any codes.

 

The actuator fork in the transfer case usually causes the 4lo light to flash. No codes will be read. Is it beeping too? If the fork doesnt engage you wont have drive gears and truck will be in neutral and roll without ebrake engaged. You could try to troubleshoot the transfer switch which controls the actuator fork.
Have you tried to re-engage 4hi to 4lo back to 2wd?

 

4lo light is just flashing not beeping. The truck can be driven forward and reverse. It's currently stuck in 4 hi as far as I can tell, which means that I shouldn't drive it much on the pavement if at all. I'm only planning to drive it to the mechanic, which will be about 3 miles. If it rains from now til then, I'm going to drop it off while it rains so as to reduce the strain of the 4 wheel drive system as the rain would make the road a little slippery.

Yes I have tried tweaking the circular knob from 4 lo to 4 hi, to 2wd, and pretty much all the different combinations, all while in neutral. The whole time the 4 lo light just keeps blinking. I've tried disconnecting the battery as well to reset the computer.

The VSC light is on, which makes sense. The VSC light is supposed to come on automatically whenever you go into 4wd, whether 4 high or 4 low. That's what the info sheet on the visor states as well.

I have successfully used 4 hi on this truck before, but never 4 lo. This was my first time using the 4 lo.

 

At 300K miles the actuator is probably going out.

 

On a 2.5 gen (should be similar to a 2nd gen) disconnect the plug on the TC actuator motor where you see these 2 fat wires. On 2.5 gen it’s this red and green wire, not sure what color it is on 2nd gen, but it’s the motor that moves the shift forks in the TC. Apply 12 volts to it and it’ll go from 2wd to 4hi to 4Lo. Change the polarity and it’ll go the other way. So basically, what I’m trying to say is force it to go to 2wd. Do this manual shift with the truck off. Apply power for about 2 seconds and the shift fork will move from one end to the other.



I’ve been manually shifting my TC this way so I know it’s possible.

 

@Cruzer , Thanks! Hopefully it helps @epicurese out. When mine won't go into gear I usually beat the case or roll it a few feet. Wonder if it's the reason they went with Borg case. Haha

 

@Cruzer , thanks. Is the reason that you're shifting the TC manually with a 12 v power source that your truck is also suffering similar symptoms as mine?

 

Oh no. I'm doing it for off roading purposes. I made something to trick the ECU into thinking it's still in 2wd while I manually shift the TC into 4LO, this way I can program the Tow Haul button for a more open throttle valve position in first gear, which will help me bump up and over an obstacle.

 

@epicurese checkout this thread. Lots of great information for you or your mechanic.

https://www.tundras.com/threads/could-use-some-advice-for-transfer-case-actuator-replacement.50162/

 

Got an initial tentative estimate from my mechanic for about $4000-$5000 for either 1) replacing the whole transfer case with the actuator (less labor intensive) or 2) replacing just the actuator (labor intensive, b/c he said the transfer case needs to be disassembled to get the rods out). That seems a bit steep.

Meanwhile, I found this gem: https://www.tundras.com/threads/2007-2020-transfer-case-actuator.61182/

I'm thinking about DIY'ing it at this point.

 

Alright, this has been resolved. I talked my mechanic into taking a look at actuator. He tried to take one of the actuator plastic cover off, but couldn't due to the screws being stuck. He then tried to take the actuator off of the transfer case, that apparently also didn't work. So he put things back together and just turned the truck on and the truck was able to get into 2 wheel drive. I guess simply messing with the actuator was enough to get something, probably one of the actuator motors, unstuck. So this ended up only costing me a little under $200. I probably still should replace the actuator at some point.