Help! 4WD Won't Engage

[tacoblue]

Hi everyone! This is my first post here - I have a question regarding the 4WD system on my truck.

I have a 2017 TRD Off-road (40k miles), and for a little more than a year I've been having an issue with the 4WD system. Variably and inconsistently (however, fairly often recently) when I flip the switch to go into 4 Hi, the indicator will idly blink. This has been ongoing since about 20k miles, but like I said, much more recently. This issue has presented itself in a number of ways, so to be thorough in case anybody else has experienced this I will list them:

- In 2wd, switching to 4hi, 4WD WILL engage but the light will continue to flash, and I am unable to switch back into 2WD
- In 2wd, switching to 4hi, 4WD will NOT engage and the light will flash

And the same vice versa from 4hi to 2wd.
(Note with the above issues - sometimes turning off the vehicle, leaving it for a while, and coming back, the system will instantly snap into the mode I was attempting to switch it to, and then run smoothly for the rest of the drive when I switch it back and forth).

I have tried all the random things to solve this by myself. Putting it in neutral, reversing it and then driving it forward, etc. The above issues happen when completely still, while driving (below 60mph, low RPMs/off the gas), in park, in neutral, and in reverse. I have taken the truck to various Toyota dealerships. The first TWO times (it's been a long journey) they said it was the 4WD actuator that was inexplicably shot. Both times under the powertrain warranty and replaced free of charge. The last few times I've brought it in, they said that they could not replicate the issue (like I said, inconsistent) or that they could not figure out why it was happening. The last time I brought it in they cracked open the transfer case, replaced the fluid, and could not find any issues. I'm totally stumped and don't know what to do. The issue seems to be pointing more towards something electrical to me, but I'm just not sure. I have wheeled my truck, but I'm pretty light on it. Nothing hard enough to cause major unsolvable mechanical or electrical issues.

I love my truck, and I don't want to get rid of it. But I frequently drive over a snowy mountain pass, and I need the 4WD to work consistently. I'd be willing to put money into it if I knew what was going to fix it. If anyone has experienced anything like this or knows how to do a more detailed diagnosis, I would greatly appreciate the knowledge.

 

[Asmara]

One follow-up question, you said that the dealer can't replicate it. Does that mean the flashing indicator sometimes stops?

 

[StormRnr]

I know a lof of Tacoma owners have trouble with the front axle disconnect. It's a mechanical thing, not vacuum and it hast be replaced.

 

[tacoblue]

One follow-up question, you said that the dealer can't replicate it. Does that mean the flashing indicator sometimes stops?

Yes. It's normal for the green 4wd indicator to flash when switching between 2wd and 4hi, but it will get stuck and the light will perpetually flash... Until it doesn't.

 

[Lava road]

This topic maybe a good reminder, if you rarely use your 4x4 system…it can get jam? Follow the manual…engage at least once a month?
I been driving a 2001 Tundra 2nd or third owner ..less than 85,000 miles…it will not engage in 4lo , and the 4 H only blinks… not our truck, owner pass away, , sons are away, To keep the truck battery charge..not street driving..
This blinking happens because of never engaging the 4x4 system.as told to us..
Aloha

 

[Biohazard]

Agree with StormRnr. Mechanical part for sure.

Might check with the guys at SleeOffRoad. They've got a ton of experience with all things off-road toyota, and I've had good answers with odd questions about my old land cruiser. Really helpful guys.

 

[solscooter]

Have you ever done a water crossing. Where water might have gotten into the actuator?

 

[tacoblue]

Have you ever done a water crossing. Where water might have gotten into the actuator?

I have done a couple. The actuator has since been replaced twice for inexplicably quitting. No water crossings since, and the last few times I've had it in they have said the actuator was working fine.

 

[tacoblue]

Agree with StormRnr. Mechanical part for sure.

Might check with the guys at SleeOffRoad. They've got a ton of experience with all things off-road toyota, and I've had good answers with odd questions about my old land cruiser. Really helpful guys.

Thank you for the info. Unfortunately I'm out of WA, so they're a little far away from me.

 

[Asmara]

It still sounds like an actuator issue. If you are confident that the dealer installed it correctly mechanically (and I assume they were more careful the second time), I would look at the electrical going to the actuator.

Are the connections good and not corroded? Connector pins fully seater in the connectors and making good contact which plugged in? Is the wiring damaged between the 4x4 module and the actuator? Check the voltage with a multi-meter when somebody turns it on and make sure you are getting good voltage. Check the ground wire to ground, is there excessive resistance? You should also hear the motor turning if you are underneath and somebody turns it on.

It could be that the current/voltage needed by a brand new, just-installed factory-greased actuator is lower than what the actuator needs after a couple of uses. Although not definitive (unless it works, then you know it is an electrical issue), a quick way to see if it could be the electrical would be to put the truck in park, increase RPMs to 2000ish and hold. Then try to engage the 4x4. That will increase your vehicle voltage to around 14 volts which may be enough to move the motor. and overcome a wiring problem. You could also connect a battery charger to the system so you don't have to run the engine assuming the charger will put out 14ish volts.

If it doesn't work and you don't hear the motor turning (BTW, I'm assuming you will be able to hear it. You might have to use a stethoscope to overcome engine noise), I'd still look at the wiring. It is still possible that the wiring is damaged and the motor isn't getting enough current/voltage to turn. Again might work when new because it is borderline but with use, the actuator is a little harder to move. It is possible that if there is too much resistance in the wiring because it is damaged, the motor is burning itself out which would necessitate a replacement.

 

[ElementRob86]

I would, going forward, make sure you test/run your 4WD system once a month as the manual states. I hope you get your problem figured out!

 

[tacoblue]

It still sounds like an actuator issue. If you are confident that the dealer installed it correctly mechanically (and I assume they were more careful the second time), I would look at the electrical going to the actuator.

Are the connections good and not corroded? Connector pins fully seater in the connectors and making good contact which plugged in? Is the wiring damaged between the 4x4 module and the actuator? Check the voltage with a multi-meter when somebody turns it on and make sure you are getting good voltage. Check the ground wire to ground, is there excessive resistance? You should also hear the motor turning if you are underneath and somebody turns it on.

It could be that the current/voltage needed by a brand new, just-installed factory-greased actuator is lower than what the actuator needs after a couple of uses. Although not definitive (unless it works, then you know it is an electrical issue), a quick way to see if it could be the electrical would be to put the truck in park, increase RPMs to 2000ish and hold. Then try to engage the 4x4. That will increase your vehicle voltage to around 14 volts which may be enough to move the motor. and overcome a wiring problem. You could also connect a battery charger to the system so you don't have to run the engine assuming the charger will put out 14ish volts.

If it doesn't work and you don't hear the motor turning (BTW, I'm assuming you will be able to hear it. You might have to use a stethoscope to overcome engine noise), I'd still look at the wiring. It is still possible that the wiring is damaged and the motor isn't getting enough current/voltage to turn. Again might work when new because it is borderline but with use, the actuator is a little harder to move. It is possible that if there is too much resistance in the wiring because it is damaged, the motor is burning itself out which would necessitate a replacement.

This is super helpful and informative. I'll try to do as much diagnosis as I can with this. Thank you!

 

[Smitty]

Yes. It's normal for the green 4wd indicator to flash when switching between 2wd and 4hi, but it will get stuck and the light will perpetually flash... Until it doesn't.

I have the same truck as you, mine does that, I found out I gotta kinda let it slowly roll forward when engaging 4WD then sometimes you hear a click. THAT'S when it's fully engaged

 

[dsrtrcr]

I have had the same issues. To get it to engage/disengage is a different procedure each time. Stopping completely. Parking brake. Slow roll back and forth. It drives me crazy.

 

[Shaun the Finn]

Seems like I share similar issues with what you are experiencing, when turning into a shopping center (small dip) at a certain slow speed (less than 10 mph) in 2H, I would hear what appears from the driver-side front gear grind or slips and sometimes the slip light will come on when this occurs. I've replaced the transfer case actuators, drained, flushed, and filled both the front diff and transfer case oil. I brought it to my friend that has a Mactool OBD diagnostics and it prompted a front ABS speed sensor code which I replaced. I went back to my friend to have it re-diagnostic and it passed with a flying color with zero codes but the problem was still there. - In 2wd, switching to 4hi, 4WD will NOT engage and the light will flash. I can hear it click and if I switch back to 4H, it seems to go back to 4H just fine. As of right now, I am tempted to replace the actuator on the front diff. But I also suspect this is Mechanical, not electrical.

 

[Tomahawk Dog]

I have a manual transmission,
At the first of the month, I make a habit of engaging 4H and 4L to keep things lubed and moving.
From day one I had engagement issues,... I was doing it wrong.
You must be moving for 4H and if going to 4L roll SLOW.
It does help to engage it by shifting to reverse then back a forward gear if the gear oil is cold or you have not used it in a while.
Its a mechanical engagement by solenoids
The light stays on by a pressure switch and will only stay on/off if the engagement/disengagement is complete.
The light will flash if the gears are not meshed.

Monthly engagement is required or it will get sticky and eventually become stuck.................... scary word warning="seized"
Old saying,.. use it or lose it

Source: https://youtu.be/-FZcmDGVEmE