4Lo not engaging, sometimes 4hi

Ok, so this past summer 4hi wouldn't engage when I asked it too, both 4hi and 4lo lights just blink in the dash...a few times it seemed liked 4hi was engaging on its own and wouldn't disengage easily. More recently, after a drive on a gravel road 4hi engaged and wouldn't disengage. I took it to the shop and they found a cracked vacuum hose and told me it was fixed, but they couldn't get 4lo to engage at all. They think it's an electrical issue with the switch in the cabin, but they couldn't find any replacement switches. 4hi engaging and disengaged no problem until I'd driven it on dirt roads a few times, and now just as likely as not it won't engage when I need it and the 4hi 4lo lights blink at me. If I turn the truck completely off w/ the 4hi button still switched to on, it'll be in 4hi when I turn it back on, no blinking lights. When I go to turn 4hi off, it'll turn off now, although not as fast as it used, probably because I drove it around stuck in 4hi for awhile and it messed up the gears? Idk...seems ok... If I try to go into 4lo from 4hi in neutral I get the blinking 4hi 4lo lights in the dash. When those lights are blinking nothing disengages or engages, I have to shut the truck off and try again. I had toyota do a diagnostic and they wanted to replace the actuator, that was before I got the vacuum hose fixed, and I don't think anything diagnostic indicated that...they were just guessing is my guess. Any thoughts? Should I look for a new 4hi 4lo button for in the dash? Are there any diagrams that tell me where to check the electrical connections and see if there is a loose wire somewhere or something? Someone told me the wiring in 2005s was real bad quality and the wires tend to go bad...

 

Open up and clean out the crap built up within the actuator or replace it. Plenty of threads on here with pictures of it torn apart and everything.

 

Oh boy here we go again. If I had a dollar ....

See the video in this reply for the likely problem (corroded actuator contacts): https://www.tundras.com/threads/4wd-issues.119382/#post-3081795

See this thread for an example of what a lot of people's caps look like: https://www.tundras.com/threads/4wd-diagnosis.132880/

50/50 chance that's what's going on if the vent tube was shot. Outside stuff got inside, corroded the contacts, and you aren't getting electrical transmission across the contact.

 

Your mechanic doesn’t know what they are doing. The 4wd system does not use vacuum for anything. It’s electronically actuated. The “vacuum” line they are likely referring to is a vent line. Most common issue with these is the actuators fail. Usually due to corrosion inside of them. Using the 4wd regularly can help to sweep the actuators and keep corrosion at bay. It’s usually just that the actuator isn’t sealed and gets moisture in there though. A thorough cleaning as @Jack McCarthy describes or replacement is the fix.

 

If you replace the actuator with OEM (which I recommend) it's running $452.36

 

Thanks guys, I'll try cleaning those leads on the actuator. I watched the video @shifty` posted, and I read the comments on the video....one guy said he did this and a cup of water came out of the actuator and the guy had been backing a jet ski into a lake recently.....guess what I did last summer...backed a boat into a lake on a shitty ramp and we were in real deep....the water was almost up to the floorboards.

So, here is another question for ya...I mentioned I drove it around in 4hi for longer than I'd like to admit, only a mile or two to work and back, every time I parked it in a parking lot a clunk would come from the front left wheel. How bad do you think I messed it up and is there anything I can do now to mitigate the damage?

 

The reality is, you shouldn't drive on asphalt/concrete surfaces while in 4WD, any mode. Every time you turn the wheels, which are locked to spin the same, they have two choices: Bind or skip. If they're really sticking to the pavement, shit is gonna bind. There's a chance the popping you were hearing was just the wheel skipping cross the ground, because that wheel was spinning more than the other due to turning.

Get it to shift out of 4HI. Then assess whether anything is still popping after. You'll probably want to drain/fill your diffs. And if you have LSD diff in rear (if you don't know how to tell, please ask), you need to be careful on fluids. Lucas 80w90 basically works universally in both diffs and transfer cases, regardless whether rear is LSD or not, I can't recommend it enough.

Beyond that, if you are dunking things in water frequently, you should really replace the vent on top of the rear diff. It's a $10 part and when it jams up, you'll blow your rear seals out.

 

On this note @StedeBonnet if you are launching a boat ever you should not just replace the diff breather but also extend it from its current location up behind the tail light.
Here's a link to my post when I did it. Missing a few pics but it'll get you started. LINK
If the breather clogs up it will blow out axle seals. This isn't related to your current issue but you should look into this ASAP.

 

Awesome thank you. I'll take a look.

On another note I attempted to open up the actuator. Mine is abit different from the video, much tighter space and instead of hex bolts it has + screwdriver bolts. I went and bought a special wrench that was low profile and would take + bits, my best attempt just started to strip the bolt, so I said fuck this I'm just gonna forward the video to a shop and tell them that is what I want done. I also didn't have the equipment to halfway engage the motor to release pressure...but I suspect I would've struggled with the bolt regardless.

 

Which actuator were you dicking with?

 

Ya, I was trying to open the wrong actuator. I got the correct one open and a cup of water and mud came out, cleaned and greased the contacts and 4hi 4lo worked fine. Almost a year later I tried to engage 4hi and it wouldn't engage I got the blinking 4hi 4lo lights. Haven't had a chance to mess with it much but the lights continue to blink with the truck on and off over a couple days which I think is different then before. Before, with the 4wd switch turned off the lights would stop blinking with turning the truck off and back on.

 

Lucky for you, since you created this thread and last posted, @FiatRunner wrote up an entire 4WD diagnostics thread I think you'll find helpful: https://www.tundras.com/posts/3729752

Dig in, you'll probably find what you need there. Given the state of the actuator in question, i.e. full of water and corroded, I'd probably still be eyeballing that as a potential cause, but there are cases (as he mentions in that thread which you should really focus on) where the wiring melts at/on/near the actuator IIRC, but I'd be looking at whether the actuator is full of water again - I'm assuming it was that way because the vent hose was toast, and if so, if you didn't replace some type of vent hose there, It's probably filled again.

 

I'll read the earlier posts when I get home tonight... but both 4HI and 4LO lights blinking typically means something is wonky with the transfer case actuator, it might not be connected. Hopefully you find the thread helpful.

 

Transfer case actuator cover before and after wiping it out, there was maybe 1/2 oz of water in it when I opened it up. Lubed it and reconnected it and disconnected battery before trying again, no change both 4hi and 4lo lights flashing.

 

Has that outer contact ring worn away in the center or it that still grime on it there?

 

Not sure what you mean, the black bits in the gold are pitted with corrosion eating at them, I took a bit of sandpaper to it but I didn't get anything to push into the pits and try to scrape them clean.

 

Yeah, that’s what I meant. Thanks for clarifying.

 

I wonder if there’s a legit way to fill the pits in the metal, refurbish it?

I’d buy a new cap (or score one at a JY) just to be sure. I’d need to dig in EPC to see if you can buy an OEM cap separately. Or to get a part number and check to see if anyone makes an aftermarket.

@StedeBonnet dis you check the two wire harnesses on the xfer case actuator to check for corroded/bent/broken pins, melted plastic etc?

 

That outer trace is whasted, dang. And that doesn't look like the standard "lube" in there.


I know you can solder to brass. If I was broke/or cheap, and have nothing to lose ide try to fill in those voids, sand-dremel it down and send it.
But solder doesnt seem like it would be hard or last very long.

 

Hmm...I inspected the wires and the connectors, there was the main wiring harness connector that plugs into the cap, that seemed in order. And then there was 4hi and 4lo sensors that plugged into the other half of the actuator, I inspected them and they seemed fine but they seemed difficult to unplug and I did not unplug them. As much of the wire as I could see seemed ok...

I thought about just getting a new cap...what is EPC?

 

EPC = electronic parts catalog.

At the top of 1st gen forum is a section of sticky threads. There is one that deals with parts lookup and points you to how to look stuff up.

 

Where did you find that, cheapest OEM I've found is $1100....$1500 full price. Honestly feel like I could try the 80$ Amazon knockoff and maybe just use the cover.

 

After watching the video of the guy repairing the front ADD from the 4wd troubleshooting thread...I'm wondering if I should go back and do what he did...the screw gear in the pictures I posted looks pretty rusty and so was his...

 

The 4wd troubleshooting thread indicates that if both lights blink that means the ECU thinks the transfer case actuator is not connected. If the motor inside the actuator were dead could that make the ECU think it is not connected?

 

AISIN makes the part for Toyota. It’s half the cost if you order from them. Look the part up here: https://aisinaftermarket.com/online

Do not order the part from an unreputable seller like scAmazon or fleaBay. Rock Auto or Summit Racing is your winner here. But I’d be tempted to hit a junkyard for ECU or a new cap or the whole actuator honestly. Save oodles of cash, and if the part is internally bad you can return it.

 

Maybe you can partially put it back together and trace it out electrically via the FSM wiring diagram and using a multi-meter to see what’s wrong? There’s probably a documented resistance to determine if the motor winding is still good.

 

That was my experience when I troubleshooted my own 4WD issues. Anytime the transfer case actuator was unplugged, both lights would blink constantly.

Considering that the transfer case actuator does not have any internal switches, just the motor, then yes. I do think it’s possible that corroded contacts could cause the blinking lights.

I didn’t have much success trying to hodgepodge an actuator- but that was mostly due to rust.

 

The sensors being difficult to unplug, so OP didn’t h plug sounds a bit suspect to me. Maybe the wiring is melted, or sensor not working?

 

I checked the wiring harnesses on them, seems ok.

I noticed today when I put the key in the ignition with power on but engine off, the differential or transfer case, the thing between the 2 actuators, was vibrating and making a slight whirring noise that kept alternating pitches.....sounded almost like an alarm with the alternating whirring at 2 different pitches. It just kept doing that until I turned it off. Not sure if that is normal....

 

I inspected the electric motor inside the actuator...didn't have any sign of corrosion....was entertaining to put back together...lol