Discussion: how to make 4wd more reliable in the 5th gen

[1engineer]

I thought having a manual transfer case like in the TRAIL, TRD PRO, or FJC was a bulletproof 4WD system compared to the push button/turn dial system in their other models? My previous Tacoma's all had the dial and often I'd hear it forcing itself in/out of 4WD. Sometimes beeping, sometimes chinking

Nate, not picking on you but I will use your post as an example!

"I thought" or "I assumed" is a common issue on many products and especially vehicles like the 4Runner.
The manual transfer case still needs solenoids to operate the ADD, or automatic disconnecting differential. So you do away with a dial and switch but still have solenoids downstream.

This is common on a lot of the operation of the 4Runner. What is also common is when people blame "Toyota" or this forum for their own ineptitude when it comes to researching operation procedures or features. How many posts have you read that people blame themselves for a problem?

Again, this thread highlights something that COULD happen and how to mitigate the potential issues that could arise from a CEL. That should be the takeaway here. Buy a code reader and learn how to use it.

To me, it's no different than losing an alternator or running down your battery or losing your keys. Any of these things happen its going to be a bad day out on the trail. The good news is you can carry a spare key, you can have a dual battery set up and now, if you leave your gas cap loose, you can tighten it, clear the codes and be back in business. Still, if your alternator craps out your are SOL up the creek with no paddle, unless you carry a spare, and who does that? My question still is how common is this problem? I have been reading threads for seven years and I only know of two instances of someone going into "limp mode" and they were not caused by a CEL or code issue. Maybe they happen and people don't post, but it seems every time anyone has a problem the first place they go is the internet to tell the world.

 

[wfo9]

I agree, this is a good subject to talk about and it sounds like a code reader is a handy tool to have in your box. But by your logic presented above and using your example, and knowing this is a rare occurrence, ANYTHING that breaks is going to make your trip miserable. A battery or alternator, your ECU, lost key, etc and if these things fail it is worse than only going into 4WD. We carry spare parts based on statistics. Nobody carries everything. My point is sure, it could happen. Is it more likely than a major electrical component like a battery, alternator or ECU? I would take 2WD versus a 4600 lb boat anchor.
Bottom line: Buy a code reader and learn how to use one.

I now consider a code reader the most important tool/recovery gear you can carry in a 5th gen. Put one in the glove box and never leave home without it....

Funny thing is.. I was suppose to go on that trip, but something came up at work. He asked me what tools and spare parts he should take. I gave him a basic list including a spare CV and tre... I told him it was impossible to cover it all... Guess what was not on that list! Even though I would have had one... I did not (at the time) have it on my must have tool list... It is there now.

And I still think it would be very useful to have a manual ADD engagement procedure/mechanism documented. I think there are still quite a few scenarios where clearing codes won't work. Now is that juice worth the squeeze of possibly causing a failure fiddling with it on a perfectly functioning truck .... maybe not.

 

[1engineer]

And I still think it would be very useful to have a manual ADD engagement procedure/mechanism documented. I think there are still quite a few scenarios where clearing codes won't work. Now is that juice worth the squeeze of possibly causing a failure fiddling with it on a perfectly functioning truck .... maybe not.

Sometimes you just have to have faith. Every time I cross a bridge I think about who designed it. I know a lot of civil engineers and I don't trust 'em...

 

[007Tacoma]

Sometimes you just have to have faith. Every time I cross a bridge I think about who designed it. I know a lot of civil engineers and I don't trust 'em...

...now think about how old they are.

...and how civil engineering has changed since then.

...and how vehicles are getting heavier (on average).

...and how bridges/infrastructure don't get "updates" until "something necessitates it" - I am looking at you Louisiana I-10 "Basin" Bridge...

 

[1engineer]

...now think about how old they are.

...and how civil engineering has changed since then.

...and how vehicles are getting heavier (on average).

...and how bridges/infrastructure don't get "updates" until "something necessitates it" - I am looking at you Louisiana I-10 "Basin" Bridge...

No, I think back about how some civil engineers I went to college with that work for the construction companies that build bridges.

 

[DeepSea]

Nate, not picking on you but I will use your post as an example!

"I thought" or "I assumed" is a common issue on many products and especially vehicles like the 4Runner.
The manual transfer case still needs solenoids to operate the ADD, or automatic disconnecting differential. So you do away with a dial and switch but still have solenoids downstream.

This is common on a lot of the operation of the 4Runner. What is also common is when people blame "Toyota" or this forum for their own ineptitude when it comes to researching operation procedures or features. How many posts have you read that people blame themselves for a problem?

Again, this thread highlights something that COULD happen and how to mitigate the potential issues that could arise from a CEL. That should be the takeaway here. Buy a code reader and learn how to use it.

To me, it's no different than losing an alternator or running down your battery or losing your keys. Any of these things happen its going to be a bad day out on the trail. The good news is you can carry a spare key, you can have a dual battery set up and now, if you leave your gas cap loose, you can tighten it, clear the codes and be back in business. Still, if your alternator craps out your are SOL up the creek with no paddle, unless you carry a spare, and who does that? My question still is how common is this problem? I have been reading threads for seven years and I only know of two instances of someone going into "limp mode" and they were not caused by a CEL or code issue. Maybe they happen and people don't post, but it seems every time anyone has a problem the first place they go is the internet to tell the world.

Thanks for clarifying. The problem you had is obviously rare but happens and in your situation is was not an ideal time. I can't help but wonder if the Expedition Overland guys had anything similar happen on their Central America trek but we'd never know because Toyota was the main sponsor and I'm sure they had the say on what went into the web series.

 

[e60ral]

Thanks for clarifying. The problem you had is obviously rare but happens and in your situation is was not an ideal time. I can't help but wonder if the Expedition Overland guys had anything similar happen on their Central America trek but we'd never know because Toyota was the main sponsor and I'm sure they had the say on what went into the web series.

they had brand new vehices with very few miles, i don't think its crazy to believe that they haven't had a CEL

 

[Black_ice_02]

on my fj I opted to run a manual/all time 4wd on the front diff after my add had issues, for 1 it was cheaper then a new add and wouldn't have continued issues. Lot of folks don't like this route cuz your driveshaft is now spinning all the time.. I'm honestly unclear if the t-case is being lubricted properly as fj's aren't good for flat-towing, but felt safe that the input was spinning and didn't mind the wear.


A good knowledge for said instance is that you can remove the add, slide the coupler over by hand and reinstall the add; the add arm in the disengaged position will fit beside the coupler and hold it in place

I also run an ultraguage to monitor my trans temps and lockup status; they find had 315's on it and would search for gear all day; if I didn't get the lockup right through mild hills the trans temps would reach 230 easily. Also the ultra gauge clears simple codes;

 

[nglayton]

So, I'm sure someone will correct me if I'm wrong, because thats how the internet rolls....:roll:

But anyway, disconnecting the battery for a minute or so (maybe longer) will also clear the codes, correct?

I'm pretty sure I've used this method on many a vehicle including a Taco......

Perhaps these were older cars? I've never tried on my 2011 T4R.

 

[007Tacoma]

So, I'm sure someone will correct me if I'm wrong, because thats how the internet rolls....:roll:

But anyway, disconnecting the battery for a minute or so (maybe longer) will also clear the codes, correct?

I'm pretty sure I've used this method on many a vehicle including a Taco......

Perhaps these were older cars? I've never tried on my 2011 T4R.

I think you are correct. Although, disconnecting the battery can have other effects and requires a 10mm wrench or socket. I can use a Scan Gauge II to clear a code while still sitting in the driver's seat (or passenger as my wife has done).

 

[nglayton]

I think you are correct. Although, disconnecting the battery can have other effects and requires a 10mm wrench or socket.

Other effects, like loosing my pre set radio stations or my MPG calculations on the dash I can live with. Those would be all relatively minor compared to getting out of a pinch and getting home......

10mm wrench I always have, even a pair of pliers of most any can kind get the battery disconnected in a pinch.

 

[007Tacoma]

Other effects, like loosing my pre set radio stations or my MPG calculations on the dash I can live with. Those would be all relatively minor compared to getting out of a pinch and getting home......

10mm wrench I always have, even a pair of pliers of most any can kind get the battery disconnected in a pinch.

My point was more to the effect that a Scan Gauge requires less time and effort. Anybody that owns a Toyota and does any kind of maintenance/modifications should have a 10mm wrench/ratchet at all times. :thumb:

 

[e60ral]

Other effects, like loosing my pre set radio stations or my MPG calculations on the dash I can live with. Those would be all relatively minor compared to getting out of a pinch and getting home......

10mm wrench I always have, even a pair of pliers of most any can kind get the battery disconnected in a pinch.

You won't lose your radio stations btw

Sent from my SM-G930V using Tapatalk

 

[infinitedev]

Back to the initial topic

I'll let you decide whether or not overriding the factory safeguards is a good thing, but I'm pretty sure this could be done by throwing a few $13 microcontrollers on the on the various CAN busses and sniffing the factory commands, then offering an interface which allows the same commands to be issued.

For example. There are people cutting/splicing wires and hard wiring (or even building interposer cables) switches in to do various things like activate the reverse camera, change the configuration of KDSS, lock the rear diff in 4hi, etc. I'm fairly confident that all this could be accomplished with a little bit of code.

There usually isn't security on a CAN bus, and all controllers on that bus can see all the commands and information being sent on said bus. That being said, there are usually 2-3 different CAN busses in a vehicle, there are several different CAN specifications, and many manufacturers have their own protocols. But its a matter of collecting and analyzing the data on the bus and correlating the data with events - IE starting a log, then locking the rear diff, and see what commands get sent.

Once you reverse engineer some of the commands, you could basically just replay them with a button press and repeat the behavior.

One thing that may be an issue is bus contention- aka issue a command, only for the proper controller that would normally issue that command to send another command to cancel that action. This could be counteracted with a "man in the middle" approach in which the bus is passed through the microcontroller, and it replays all the commands to the target controller, filtering out the cancel commands.

Obviously, this could potentially be very dangerous, as if your micro were to fail, on a critical system, you could introduce unknown behavior.

Anyway... that's my 2 cents. Carry on.

 

[SATSTRAIL]

I'll let you decide whether or not overriding the factory safeguards is a good thing, but I'm pretty sure this could be done by throwing a few $13 microcontrollers on the on the various CAN busses and sniffing the factory commands, then offering an interface which allows the same commands to be issued.

For example. There are people cutting/splicing wires and hard wiring (or even building interposer cables) switches in to do various things like activate the reverse camera, change the configuration of KDSS, lock the rear diff in 4hi, etc. I'm fairly confident that all this could be accomplished with a little bit of code.

There usually isn't security on a CAN bus, and all controllers on that bus can see all the commands and information being sent on said bus. That being said, there are usually 2-3 different CAN busses in a vehicle, there are several different CAN specifications, and many manufacturers have their own protocols. But its a matter of collecting and analyzing the data on the bus and correlating the data with events - IE starting a log, then locking the rear diff, and see what commands get sent.

Once you reverse engineer some of the commands, you could basically just replay them with a button press and repeat the behavior.

One thing that may be an issue is bus contention- aka issue a command, only for the proper controller that would normally issue that command to send another command to cancel that action. This could be counteracted with a "man in the middle" approach in which the bus is passed through the microcontroller, and it replays all the commands to the target controller, filtering out the cancel commands.

Obviously, this could potentially be very dangerous, as if your micro were to fail, on a critical system, you could introduce unknown behavior.

Anyway... that's my 2 cents. Carry on.

That's all theoretically possible with some very high-tech computer programs and equipment. Even factory scan tools etc. will not allow you to do anything remotely like that. The effort and risk involved with that is way too high for 99.9% of people even ones who are very skilled. If you are able to do all of that you might as well just engineer and build your own off-road vehicle from the ground up. Don't even buy a 4Runner...

Just carry a code reader and the .9% chance that you have a DTC set that can't be resolved with the code reader and that will actually re-trigger the DTC upon first start up (which is rare) will likely not ever happen in the first place.

Most common DTC's with the exception of catalyst damaging misfires require two trip detection logic and therefore you should easily be able to clear the code travel, clear the code travel, etc.

 

[infinitedev]

That's all theoretically possible with some very high-tech computer programs and equipment... The effort and risk involved with that is way too high for 99.9% of people even ones who are very skilled.

That's a bit of a stretch. There are plenty of people out there who are reverse engineering the CAN bus on their vehicles. A 10 second search revealed many links, with these being among the top results:

CAN Hacking: The In-vehicle Network | Hackaday
https://theksmith.com/software/hack-vehicle-bus-cheap-easy-part-2/
CanBusHack ? Hack Your Car
Hack Your Vehicle CAN-BUS With Arduino and Seeed CAN-BUS Shield: 6 Steps

Surely if a Jeep owner can do it, so could others.

If you are able to do all of that you might as well just engineer and build your own off-road vehicle from the ground up. Don't even buy a 4Runner...

I'll let that one go

Just carry a code reader and the .9% chance that you have a DTC set that can't be resolved with the code reader and that will actually re-trigger the DTC upon first start up (which is rare) will likely not ever happen in the first place.

I'm not disagreeing with you on that. Just wanted to present an alternative approach.

 

[SATSTRAIL]

That's a bit of a stretch. There are plenty of people out there who are reverse engineering the CAN bus on their vehicles. A 10 second search revealed many links, with these being among the top results:

CAN Hacking: The In-vehicle Network | Hackaday
https://theksmith.com/software/hack-vehicle-bus-cheap-easy-part-2/
CanBusHack ? Hack Your Car
Hack Your Vehicle CAN-BUS With Arduino and Seeed CAN-BUS Shield: 6 Steps

Surely if a Jeep owner can do it, so could others.



I'll let that one go



I'm not disagreeing with you on that. Just wanted to present an alternative approach.

Yes there was a bit of sarcasm with my "engineer and build" comment. My point is that some of these "solutions" are way overkill for the potential issue at hand.

 

[007Tacoma]

I still like the theoretical approach if for nothing else to explain alternatives and provide information as to why those alternatives may or may not be the best idea. I really appreciate the information you guys are putting out there.

...now will I ever use it? Hopefully/probably never, but I would rather know than be ignorant.

 

[nglayton]

My point was more to the effect that a Scan Gauge requires less time and effort. Anybody that owns a Toyota and does any kind of maintenance/modifications should have a 10mm wrench/ratchet at all times. :thumb:

Ah, yes, but my point was that this whole thing is much ado about nothing when all you have to do is disconnect that battery for a few and everything resets.

So as the OP stated being 1000's of miles from home and pre-planning for how to handle this type of 'emergency' would require nothing more than a 10mm or pair of pliers that you probably already have.

Making overrides, manually pulling cables, hacking the CANBUS, writing code and all the other crazy stuff mentioned above is just plain nuts. Besides being nuts it will just add another degree of unreliability to the system.

Call me crazy, but I will just carry my standard set of tools and be just fine.

 

[Haycock]

Simple answer... install dual air-lockers and your degree of reliance on 4x4 mode is GREATLY reduced... done... you're welcome...

Haycock

Thought this might be worth a discussion.

I know some people will get bent out of shape on this subject because it is not popular to talk about the weaknesses of these trucks here... but hear me out for a second and try to be open minded.

A recent experience of a friend with a 5th gen made me realize how unreliable these trucks are when it comes to the part time 4wd system. Especially as they age and start getting a decent amount of miles on them.

The system itself is not unreliable, it's based on a solid foundation of reliable mechanical components... However, Toyota has made any malfunction that throws a MIL/CEL on the entire truck.. disable the 4wd system. This means that lots of fragile sensors need to all be happy for the system to work, even if the sensor has absolutely nothing to do with 4wd or the normal operation of the truck.

Here is the scenario... you are out the desert camping and exploring for 2 weeks thousands of miles from home. You get a simple CEL/MIL set. This could be anything from a loose gas cap, to a catalytic converter efficiency or EVAP code, to an actual engine misfire. Well guess what... no ability to engage 4wd and your trip is a bust unless you can resolve the issue. Even when the truck is running perfect....

Why? Well even though you tried to think this scenario through and purchased a trail edition or one of the older sr5s with a manual transfer case, Toyota decided that anytime a MIL is set.. Disable the 4wd ECU and don't allow the ADD to engage the passenger side axle. If you add a front locker... you can still get 3wd... but that configuration puts major stress on the single CV and would not be ideal.. There is no logic behind the 4wd being disabled besides the fact that they just wanted to treat any malfunction the same and force you into a dealer vs only disabling 4wd for relevant problems. My guess is that it will stay in 4wd if you are already engaged... So any reasoning that 4wd can't operate without all the sensors happy is not valid.

The chances of something like this happening are pretty high as the vehicle ages... and many of the emissions codes are just part of owning an older vehicle. I realize 5th gens are only about 7-8 years old now and this is currently not that common, but in 5 years from now these types of issues will be fairly common and many people won't care that their catalytic converter needs to be replaced while out in the middle of nowhere.... Yet they won't be able to use 4wd unless they come up with a solution.

Another unrelated yet common problem is the tcase switches that fail. These will also disable your ability to use 4wd, but are really only ECU related.

What I would like to do is discuss how the ADD could be wired up to engage via an override switch. That is the only thing mechanically stopping 4wd from working on a manual T-Case truck. Just like you can hard wire the rear locker it should be possible to hard wire the ADD. I have not even looked at the wiring diagram yet... but it is on my backlog of things to do.

The next question would be... If the ECU does not know it is in 4wd... and you got the ADD to hotwire or manually engage.. How would TRAC and all the other fly by wire electronics limit the trucks ability to go off-road. Things like ATRAC, crawl, and all the other electronic gadgets would not work, but would the basic traction control get in the way of actually offroading the truck. 4LO normally turns off most things, so the truck actually works with wheel spin. Regular 2H behavior is pretty odd when the wheels start to slip unless you can disable the traction control, but I'm hoping all that gets disabled with a MIL or you can still manually turn it off.

This is not a priority for me at the moment, but something I want to research as time permits. I feel it is an inevitable situation as the truck ages and it would be nice to have a mitigation strategy in place. I use this truck to do long trips offroad.. and if the truck fails... the trip is a bust. I understand mechanical things can and will happen... I can accept that, but that is the reason I have the 4r vs a Jeep. The BS electronics are much more frustrating if they stop you and I feel Toyota has made a mistake here.