Not your average 4wd problem

2002 tundra 4.7L 4wd

My 4wd dash light is blinking. PLEASE-READ ON. I already replaced the transfer case actuator and front differential actuator. My 4wd works when I press 4hi button on dash and comes out when I press it again. But 4wd light on button and dash blink when in 4wd. No blink when out of 4wd. 4lo button does not stay in when pressed and 4lo does not engage or blink at all.
When replacing the transfer case actuator I moved the gear rod into 2wd, 4hi, and 4lo successfully. I know the transfer case and front differential are working fine.

Anyone know why my light is blinking and no 4lo???? Can I bypass the dash switch? Please help.

AL

 

Wow, what pain - especially after replacing the common culprits.

Are you using the troubleshooting in the FSM?
From the first page:
HINT:
Inspection should be performed with the vehicle stopped, and transmission shift lever in N position.
If switching is not completed after 3 seconds of shift operation, the 4LO indicator light will flash.

There are multiple links to the FSM on the forum here. Let me know if you can't find a copy.

Rich

 

So just to clarify,

4wd works, but the light blinks and no 4lo? Does the dash say 4hi or 4lo when you press the buttons?

 

Short answer, can not go to 4Lo unless 4Hi is working.

Probably but why would you not want to fix the issue. While these 4Wd's can be somewhat complicated, they are rock solid if maintained properly.

What caused you to even replace both actuators and are they new or used ?
Just to make sure, when attempting 4Hi, are you moving forward and/or reverse ?
This honestly is an average problem for those that have come thru here with this issue !

 

Dash blinks 4hi when in 4wd after pressing button in. Dash light goes off after letting button out. 4lo button has no response when pushed in. (Nuetral on shifter).

Note: when I disconnected 6 pin plug on transfer case actuator, the 4lo button blinks and the 4lo dash blinks along with 4hi. So the circuit appears complete. I am puzzled.

thanks for the input

AL

 

I list 4wd completely on the beach and friends towed me out. I replaced the transfer case actuator because there was no sound. I think i was a tooth or two off when timing the worm gear and shifting rod so I still had problems. Replaced differential actuator, changed all fluids, retimed the transfer case actuator, and got 4hi and front axle locked with 4hi lights blinking on dash and button. Goes in and out smooth. That’s where I am at.
AL

 

Al, when you go to 4Hi are you moving the truck either forward or reverse ? 4Lo will not activate until 4Hi engages !

Hmmm….simply thinking out loud…..”signal is sent to T-Case Actuator (front drive shaft is given life) --> signal is sent to the Front Diff Actuator(CV's are locked in and you are now in 4HI)”

re-visit T-case actuator timing ?

 

Uhg. I would have to play with that by realigning the rod teeth with the gear teeth. I had a few tries with that already. The only time it worked, besides where it is now, was when it went into 4wd and I could hear gear sounds chattering as the drive shaft(front) turned. It seems obvious that the gear rod in transfer case must be at its inner most point(2wd) and barely pick up the teeth on the round worm gear. This is so that the gear shaft can move outward toward 4hi and 4lo. If the shaft is out any further than its’ inner most point it cannot actuate(move) within the actuator housing to get far enough to engage 4lo. Am I correct? Or is there a tooth or two that I can pick up on the gear rod that will affect the blinking lights? I may have already tried that in my timing endeavors or previous attempts. I did not get it first shot.

does the position of the large plastic gear in actuator with metal contacts have a certain starting point? Or is it simply the gear rod and worm gear relationship that matters?

AL

 

Yes moving when I engage 4hi with 4hi button pushed in. Again, 4lo button does not stay in when pushed.

 

This is my suspicion...one tooth either way could cause this. There are two position sensor switches on the actuator that trigger on the dents in the actuator rod. There is additional position sensing inside the actuator. Did you say whether this is a new or rebuilt actuator? I'd start by putting it up on jack stands and cycling through 2WD, 4HI, 4LO. Once you confirm that the transfer case and front diff are engaged, then you can trouble shoot the logic (there's a thread on here somewhere for that). I installed then re-installed my transfer case actuator because I didn't get the actuator rod/gear thing right. You can remove the actuator and manually move the rod to confirm the right starting position. And you have to make sure the actuator is in the correct position before you drop the gear back in. Also, the FSM...

 

Brand new actuator on transfer case and front differential. Also drained and replaced differential fluid. Topped off fluid in transfer case.
I know the actuator rod was in 2wd when actuator was installed. Also moved actuator rod to all 3 positions before installing actuator while spinning wheels and front drive shaft locking in front axle.
I feel the components for 4hi and 4lo are sound thru drive train.
Back to the button used to engage 4wd on dash:
Should the 4lo button stay in when pressed? Like the 4hi button does?
Or should in spring back out to original “off” position?

my 4lo does not stay in

AL

 

W666,
When you say, “may sure the actuator is in the correct position before you drop the gear back in”… do you mean the plastic gear with contacts inside the black plastic cover? Or the worm gear inside the triangular 3 screw cover on back side?

AL

 

Oh, you've had the cover off the new actuator? Then the answer is definitely both.

The FSM is available below. The troubleshooting table begins on page 2394.

https://drive.google.com/file/d/0B9...aGM/view?resourcekey=0-IUgFBrEgIe9zfnbQv0LhaA

 

This is the simplest explanation I can find in the interverse:

https://www.yotatech.com/how-tos/a/toyota-tundra-how-to-replace-transfer-case-motor-actuator-414483

This one has all the info too:

https://www.tundras.com/threads/2007-2020-transfer-case-actuator.61182/

Bon chance!

 

Hmmm...your friends towed you out? If you were in the water deep enough to cover the actuators, then your problem may well be electrical.

 

I was stuck in the sand. Because the truck has a posi rear end and I aired down my tires to 18lbs., I made it about 200yds onto the sand. Then I started to sink and realized no 4wd. I knew not to make it worse or it takes a tow truck to get out. The actuator was making no noise or vibration so I asked my friends to pull me back to pavement.
Thanks for the info. It will be useful

The bottom line is the truck has 4wd 4hi with a light blinking on dash and button. Two new actuators and fresh fluids. Still not bad for 200,000 miles and still runs like a top…. Did I just say that?

AL

 

I realize I'm repeating but ....you can push 4Lo button all you want but unless you are in 4Hi, you can not go to 4 Lo !

 

Other choice tasty bits from the Owners Manual most people seem to use as a glovebox weight regarding flashing like when shifting 2WD > 4HI. Ignore the red box, look at section (c) next to it.

 

I use 4wd every weekend and all winter.

 

I was talking about the information to the right of that box in section (c), 2nd paragraph, 1st sentence.

 

Understood. So if it stays blinking after this procedure then it is not fully in 4hi. Is it possible that when I installed the new transfer case actuator, the plastic gear under the plastic cap is off a few teeth? The dash light was not blinking until the button was pushed in. It is brand new and so is the differential actuator.

 

It's either not fully in 4hi or maybe whatever switch tells it that it's in 4hi is damaged or not adjusted right. Although I couldn't tell you where that would be located. If the truck doesn't know it's in 4hi even though it technically is then it won't let you shift into 4lo and you'll most likely get the buzzer noise.

4lo switch will always pop right back out after pushing it. It isn't the same as the 4hi switch

 

Thank you for clarifying the switch. Ironically I needed 4wd last night and it has mysteriously vanished. When I parked the truck it had worked. I did not leave it in 4wd. Maybe I should have. 4hi lights are blinking when 4hi button is pushed. As I said, NOT YOUR ORDINARY 4WD PROBLEM.
I will remove the transfer case actuator cover tomorrow, reset the inner wheel with contacts at 3 o’clock, check the 4hi dash light, and reinstall the little worm gear attached to the shifting rod. With two new actuators working correctly when hand checked, I am about out of ideas.
AL

 

UPDATE: I removed and reset both actuators(transfer case and front diff.). The system worked in and out 20 times into 4hi. Dash light 4hi still blinking. Nothing at all for 4lo. Left in 4hi overnight. 4Hi still engaged in morning. Once button pushed in to put in 2wd it would not go back into 4hi. 4hi light blinks when 4hi button pushed in. This is confusing. At wits end.

 

I still believe that something is out of sync in the system.
I understand you made sure that everything was where it should be prior to installing new actuators, but obviously something isn't happy. Get the entire truck off the ground, key on, engine off, in neutral, and verify that when the 4HI switch is out (dark) you should be able to spin the front drive shaft by hand without spinning the front tires (Indicative of the A.D.D. actuator not engaged)
Leaving the truck in neutral, grab the rear drive shaft and verify that the front drive shaft does not spin (indicative of the transfer case being in 2HI)
Once you can verify that both actuators are in their neutral (free) position, push the 4HI momentary switch and you should hear the Transfer case and A.D.D. actuator engage and shift the T-case to 4HI.

Now you should have resistance in the front drive shaft, and the front tires should spin as well.
If you have resistance at the front axle or the T-case when in 2HI, the respective actuator is out of sync with the computer and is confused.

At this point, you'd have to remove the actuator, reset it and reinstall it.

IIR, the A.D.D. actuator slides from right to left to engage the front axle spline lock. So, the fork should be all the way to the right when not engaged.

The T-case actuator pushes the rod inside the case forward to engage 4HI and then pushes it forward again to engage 4LO. Make sure the rod that sticks out of the rear of the T-case is all the way aft when in 2 HI.

I hope all this makes sense...

 

Is it easy to spin the driveshaft? Would spinning the tires and watching the driveshaft be easier? More leverage?

 

It might work. I can't remember if the differential in the front axle would work that way. I guess it should. When I rebuilt my 4WD system, I was under the truck already, so I just grabbed the drive shaft and started turning it.
It does turn fairly easily.

 

^^^^ This

 

Good advice. I have done that several times. It is all good. I have had 4hi many times with light blinking and the after I shut the truck off it does not engage again until…I left the negative off the battery last night and was able to get the front axle to lock up today and 4hi on and off many times. I shut the truck off in 4hi, went for a break, came out and started up in 4hi and when i took it out of 4hi it would not go back in.
The transfer case actuator works every time. It is the differential actuator that is only going in after battery disconnected overnight. WTF?
It is a new transfer case actuator and new differential actuator. Tccm?

 

I am willing to bet that if I can get the information on how to rig a two pole switch to the front differential actuator properly, i can simply trip the front differential actuator to move the fork that moves the differential clutch wheel left after the transfer case actuator moves into 4hi. And then back to the right after i put it in 2wd. It is that simple. Not as bad as getting out and locking hubs. But I should not have to do that.