Hello to all! New to the forum , long time lurker in desperate need of help!!! I have a 1990 Toyota 4Runner 3.0 v6 auto trans 4wd with a.d.d. , 350k miles, had the truck since I was 17 now my daughter is driving it to college. It's been wheeled hard for years and never had any engine (original HG) or trans problems .... until now.
​​​​​​​The problem is after it sits overnight it starts out in low range. This only happens a few times a week, not every time. When it does happen it is not in 4wd, I know what low feels like and it is definitely in low. After about 2 miles of 30mph @4k rpm it snaps out of it. Nothing else helps, letting it idle, shifting in and out of low with selector. ..ect. Also when it is doing this and I'm driving I can shift to neutral and it engine brakes...? I have changed the shift solenoids in trans and tranfercase, fluid and filter and changed the valve body in the transfer case. Has anyone heard of this or have any idea what the cause could be? My understanding is that low is controlled by the solenoid on the t-case valve body? But when in low and shifted to neutral it doesn't engine brake, just coasts... so what really happening? Any help would be awesome!!!!

 

In low, but not in 4wd? And, you're sure it's not just starting out in first and just delayed getting to second? I know what you said, so I don't mean to question your intelligence, but I've been having a similar issue with my tranny. And, how do you know it's not in 4wd?

 

Thanks for your reply!!! Definitely feels exactly like low, can feel it up shift quickly and rpm same as in low. I could be wrong but ive owned the truck for well over 10yrs and work as a mechanic. I believe its not in 4wd because the axles are not binding on sharp turn like it does when shifted to 4wd. I cant find any info on how it works or what controls transfercase solenoids, ect.... the weirdest thing to me is the engine braking in neutral???... thanks again for responding.

 

Well, to be honest, I'm probably not the person to really help. I've had my own A340 issues and in a "learning" phase. In my research, though, I found this thread on a different site:

http://www.pirate4x4.com/forum/toyot...sues-faqs.html

There are links provided to the FSM that, since you work as a mechanic, you should be able to get somewhere with. I'll be following this, though.

 

I'd make sure the transfer case shift mechanism isn't bent before anything, making sure that pivot bushing thing isn't worn out or missing. I bent mine once backing up in a mud hole with submerged rocks and tree parts and bent it. Wouldn't shift into low after that. I bent it back with my hands. No biggie.

 

The L position isn't really a function of the t case, is it? I mean, even 2wd models have an L position. L4wd is the t case, right? If that's the case, then that would take the t case out of the equation.

 

4L IS a function of the transfer case (2.659:1). The "L" on the automatic shifter just keeps the automatic from shifting out of first. So first gear in the auto (2.804:1) combined with 4L is really low.

Have you run diagnostics on the transmission? http://web.archive.org/web/201408161...31diagnosi.pdf 4L is controlled by solenoid 4. I suppose it is possible that the transfer case is shifting to "4L", but the ADD isn't getting the word so there is no drive to the front wheels (which means no binding on sharp turns)

 

My questions were a tad rhetorical in nature in the event I'm dead wrong, but I suspected I wasn't. So, like I said....and you confirmed.....4L is a function of the t-case. L is transmission....IOW's it's 1st gear. Back to one my first questions to wtbash...."are you sure it's not just in first?".

Right...in order for it to actually be in 4wd, the the vacuum actuators would have to be engaged. But, how in the heck could the t-case be "starting out in low" and then snap out of it if the t-case shifter isn't being manipulated? I mean, the t-case is manually controlled, right? Like mike said, linkage? I'd bent mine when I wrecked our '92 4rnr, but it never did what wtbash is experiencing. I'd have to use the shifter to go in and out of 4L, but it would often pop out of 4L into 4H until I fixed the linkage.

 

He seems pretty certain the transfer case b3 is engaged, but c4 is not. Note the part where he says the transmission is up shifting.

 

Were the part changes before or after the symptoms?

The transmission does shift 1-3 when this is happening?

L4 should brake not coast, this seems normal.

Have you visually confirmed no front shaft movement?

If the computers are the issue you'll see 12v on #4 solenoid, and or 0v on TCCS l4.

​​​​​​​Just for reference. I ran a quick check with the gear calculation. Stuck in first gear speed at 4000 is just under 30mph, low range in third is slightly over 30mph.

 

I did. It's why I wondered if he simply wasn't getting delayed upshifting and not necessarily in 4L sans front shaft engaged. But, I think I'm getting a clearer picture of what's happening (while I'm learning... )

 

I have a 95 4runner thats acting similarly. When you start it, it acts like its in 4 low. Would a bad #4 solenoid cause this

 

#4 is the gear reduction solenoid, as mentioned above..

Could be the torque converter or clutch packs slipping also, iirc but I avoid transmission work like warm tunafish in mayo *bleeck*..

You need to determine if it's slippage or a faulty solenoid or solenoid signal.. run the diagnostics..

 

Hey folks, Reading through this post made me think of similar problems I had with my '93 Volvo 850. The research I did on that issue led me to the neutral safety switch. Looking at a picture of the neutral safety switch I see that it is constructed quite the same as the one on my Volvo. It seems that age and use of said switch can create its own problems due to wear and dirt buildup inside the switch. I used to just sit in the car and physically shift through all the gears about 20 times to clean up the contact points inside the switch. This worked well for some time until it started showing symptoms again. I wound up pulling the switch out, pulling the switch apart, cleaning up ALL of the contact points, and reassembling the switch with a light coat of dielectric grease. All of my problems went away and haven't returned. All it cost me was time. I'm not saying this is the problem but it might be something to consider.
These neutral safety switches are not the old style on/off switches. They have lots more contact points which concern every shift to every gear. Especially when shifting manually.

 

mine is just a DPST , one shared connector and two outputs, as far I know but didn't disassemble it that's just based on the wiring and expected test results.. no imhave something new to occupy me for a little bit hurray!

 

Well I guess they are due for a cleaning and fresh lube after all. Particularly since the starter current runs through there they might need a Polish aswell.. not thrilled with where the tcase cooler is located an inch back and it wouldn't be in the knuckle busting region...

4wd switch is an easier one, left side.

​​​​​​

 

If it was stuck in 4wd without the fear lever being engaged, would the ADD even engage the front end? Front axles wouldn't turn unless the add solenoid gets vaccuum, correct? I know it's a side not in this thread, but I'm still curious. Does the xfer case control the ADD.

 

add vacuum switch array is fully electrical controlled based on the 4wd switch. So with the front propeller shaft spinning via engine power it would be like the left wheel is on ice and the right stationary. You wouldn't be able to rotate the prop shaft but wouldn't be getting any drive to the front wheel that's connected without a locker of some sort.(add only disco the left shaft)

At some point they did/do put the VSV under the transmission computers control.

Anyways..

For an a340h there is still the manual valve involved (as shown in the hydraulic diagram, upper left) if the valve body is damaged or the seals let loose it could exhibit the problem seen in the original post. Particularly if the seal or other debris is circulating in the system. Actually that's a more likely scenario than the solenoid being intermittent shorting to a power line, stuck or just flopping around with a bad spring..

 

Did you ever solve this issue? I have the exact same symptoms on my 93. It starts out in low range and shifts through at least 1 and 2nd and sometimes 3rd . Then when it is warmed up like 2 miles it snaps back to 2WD HIGH again and it acts normal in 2WD like nothing happened.