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

[sigepbiker]

While I was doing some research on a 4WD swap, someone on one of the popular forums (Pirate4x4, ih8mud, tacomaworld, or maybe it was rocksolidtoys) swapped his Tacoma from 2WD to 4WD. To get around the front differential, he made a pull cable for engaging it. His taco, the 4th gen, and 5th gen all have the same front ADD.

The short of it: the electronic portion rotates to push the collar over to engage the front drive line. By replacing the electronic portion with a bolt on bracket with the cable as the rotation input, he was able to have a manual transfer case and a pull cable front diff.

And now I can't find the link or picture, but I am positive he was working on a Tacoma.

ADD Actuator: P/N 41400-35033

 

[changingtime]

Purchase a limited and part of the problem would go away. Although, assume you couldn't go 4H or 4L...but would have to have full time 4wd.

 

[TrdinOhio]

Your thread title is nothing but click bait. The components are reliable. Reading your post, you want to find a way to bypass Toyota programming logic to keep certain mechanical systems operational.
This has nothing to do with reliability and everything to do with the inability to troubleshoot and repair the electronics necessary to keep specific subsystems functioning.
In my world, you are looking for a way to "bridge out" multiple fail safes in order to keep your machine operating. Right? Here is a partial quote from your post:

"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."

Basically what you are saying is, and truthfully so, is we (collectively) do not have the ability to fix or repair the electronic components necessary to provide proper operation of this vehicle. I would agree.

I'll be happy to change your title.

Poetry.
I'm not sucking up cause I really don't give a rats ass if your a mod or not. I do like it here but whether I can post here or not will not make me lose sleep at night. That being said...this is awesome and about as bruntly truthful as I've seen on a forum. Kudos 1engineer, I'd buy you a brew ski if I overheard that in public.

 

[1engineer]

Poetry.
I'm not sucking up cause I really don't give a rats ass if your a mod or not. I do like it here but whether I can post here or not will not make me lose sleep at night. That being said...this is awesome and about as bruntly truthful as I've seen on a forum. Kudos 1engineer, I'd buy you a brew ski if I overheard that in public.

Hey, most people quote me just to argue lol.
I like this thread and have actually learned something here. Whoever that poster above is seems to know his shit about our electronics and logic. Dude, who are you?
Edit: [MENTION=157376]SATSTRAIL[/MENTION] mind sharing a bit of your background?

 

[Antman]

Isn't there an electric motor in there that actuates whatever to engage 4wd?

If so it would be easy to isolate the power/ground for the motor and run it till it's engaged (for an emergency).

I bet I could figure it out if I had to- but I'm not willing to do so and risk freaking out all my ecu's, lol.

If you unplugged the wire harness at the add and had another harness that just fed the motor on a switch that should be sufficient to engage it. I would bet no ATRAC though.

 

[wfo9]

Not to totally derail your thread. But coming from a JK wrangler (2dr rubicon, manual trans), i'm amazed how much better the Jeep traction control works than ATRAC, primarily once you lift a wheel or two. At least in my experiences, the Jeep system was much smoother. Might just be what i was doing, so feel free to take it with a grain of salt.

I've never owned a JK but from my observation of wheeling with them many times.. The brake activated traction control is no better than ATRAC... In fact, I've never seen a Rubicon use it. They always just use the lockers.. but I have seen the other non rubi JKs utilize the system. It has a ton of hesitation in it... more than ATRAC. When a wheel is in the air...(mainly the front) the other wheel get more bite because of better geometry for crawling.... of a solid axle... Solid axles are always smoother. Anytime IFS slips... there is deflection and this is why ATRAC often makes me cringe. It will start to hop and shudder... and I just start listening for that POP... Unfortunately. comparing a 2dr Rubicon and a 5th gen is apples and oranges in every possible way. It's a dedicated short wheel base off-road machine from the factory.. vs a grocery getter road boat SUV from the factory. The 4runner can be made to hang with one in some conditions, but really hard to compare them. Each has huge strengths compared to the other when general use is concerned. For pure offroad... JK wins in most conditions.

 

[wfo9]

Yep unplugging the O2 sensor would cause a failure immediately or most likely on your second ignition cycle because most DTC's have two trip detection logic where the ECM needs to see two consecutive failures before it turns the MIL on. The ECM would be seeing the O2 heater circuit open as well as the actual sensor signal circuit. If you really wanted to test it out you could unscrew the oxygen sensor from the exhaust stream but leave it plugged in that way it's not getting an actual oxygen reading from the exhaust stream.

Good idea I can probably come up with something to let one downstream sensor get some fresh air..

All my previous experience with these things were simple. I would just go in and disable the code/test and never have to worry about it again. Unfortunately that is not possible with a locked system ;-)

The other odd thing is that when trying to diagnose a cat efficiency problem.. It seems that many people claim it can be the upstream WB o2 sensor on a modern Toyota. This does not mach up with my previous experience on other brands.. If an upstream 02 was bad.. you almost always got lean/rich code independent of cat efficiency. I'm curious to see what his fuel trims look like... He already tried replacing the downstream o2s... now he wants to try the upstream, but I told him to stop throwing parts at it and to do some actual diagnosis with a scanner first.

 

[wfo9]

Isn't there an electric motor in there that actuates whatever to engage 4wd?

If so it would be easy to isolate the power/ground for the motor and run it till it's engaged (for an emergency).

I bet I could figure it out if I had to- but I'm not willing to do so and risk freaking out all my ecu's, lol.

If you unplugged the wire harness at the add and had another harness that just fed the motor on a switch that should be sufficient to engage it. I would bet no ATRAC though.

Yea,,, there are six wire (I think). Some are used to power it in different directions and some are used to signal when it gets to the end of the travel in each direction. It's almost identical to the e-locker in it's function. It will probably require a little micro controller to drive it correctly, but it would be a fun exercise to figure it out.

 

[SATSTRAIL]

Hey, most people quote me just to argue lol.
I like this thread and have actually learned something here. Whoever that poster above is seems to know his shit about our electronics and logic. Dude, who are you?
Edit: [MENTION=157376]SATSTRAIL[/MENTION] mind sharing a bit of your background?

I'm nobody special. I've been an auto technician for 18 years and 13 years as an ASE/Infiniti certified master technician at an Infiniti dealership in Arizona.

All vehicles no matter who the manufacturer is are required to operate under federal OBD2 operating standards/parameters. There are some subtle differences between the manufacturers but essentially they all operate the same.

The deactivation of the 4wd system on the 4runner due to a stored DTC is definitely a bummer. And bypassing it will not be as simple as creating your own harness to splice it in to the four-wheel-drive control unit. Modern day vehicles are required to operate using a CAN system. This CAN ( controller area network) System operates on a 2 wire 2.5 V low/5V high communication system. The principle is that all control units on the vehicle communicate to each other through these two wires using serial data. The encoded information is sent from one control unit out to all of them but only the control unit that can use the specific data will interpret it and use it. However all control units have to see constant communication with one another. If this communication between control units is lost then U1000 DTC's for the controller area network will be stored in multiple control units and cause issues throughout the vehicle systems.

Since in my experience most triggers of the check engine light are from intermittent issues my first course of action would be to take a code reader that is capable of clearing the DTC. If the issue is intermittent it may not ever happen again ( for example a bug or a piece of debris gets caught on the hotwire of your mass airflow sensor setting a trouble code) and clearing the DTC will get you home. Worst-case scenario you have to clear it a couple of times on your way out. I would like to revert to this strategy rather than hacking into the factory wiring and changing things that may cause significant other issues.

Again I state none of this as fact as I am not a "Toyota expert" however Toyota is required to operate under the same standards and parameters as every other vehicle manufacturer.

 

[flyrv9]

I don't know about the 4Runner, but I've had 2 O2 sensors go bad in my Tundra. 2000 Tundra has 2 on each side. Both threw a code telling me which one it was. Also, they were rather difficult to remove - guess they didn't use anti-seize!

 

[SATSTRAIL]

Good idea I can probably come up with something to let one downstream sensor get some fresh air..

All my previous experience with these things were simple. I would just go in and disable the code/test and never have to worry about it again. Unfortunately that is not possible with a locked system ;-)

The other odd thing is that when trying to diagnose a cat efficiency problem.. It seems that many people claim it can be the upstream WB o2 sensor on a modern Toyota. This does not mach up with my previous experience on other brands.. If an upstream 02 was bad.. you almost always got lean/rich code independent of cat efficiency. I'm curious to see what his fuel trims look like... He already tried replacing the downstream o2s... now he wants to try the upstream, but I told him to stop throwing parts at it and to do some actual diagnosis with a scanner first.

Your friend should also look for minor cracks in the exhaust system especially around welds that can allow extra oxygen into the exhaust stream before the rear O2 sensor. These cracks can especially occur from off roading since the exhaust can get hit by rocks and other debris. The change in oxygen content readings due to an exhaust leak can cause a catalyst efficiency failure code along with a variety of other codes. Just something to check into if sensor replacement has not resolved the issue…

As a sidenote, most vehicles from approximately 2006 and newer do not use oxygen sensors in the pre-catalyst positions where 02 sensors were customarily used. Now what is used are air/fuel ratio sensors. The downstream positions are still O2 sensors. The difference between the two sensors is that an oxygen sensor reads precisely that, oxygen only. And air/fuel ratio sensors are capable of measuring the exact stoichiometric air/fuel ratio and can sense the combination of air and fuel in the exhaust stream. This provides a much more accurate reading to the ecm for more precise fuel trim calculations.

 

[Ray Dunakin]

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.... .

Holy carp! That is something I was unaware of, and yes it certainly has the potential to be a huge problem for me.

Due to my wife's health issues, I only get one shot per year at taking a "big" 5-day trip, and then I'm far, far from any dealer. Even if I could get it to a dealer it would eat up what little time I have. I will be EXTREMELY pissed if my vacation is shot just because of some piddly error code disabling my 4wd for no good reason. Also, what if the only way out of wherever I am, requires 4wd?

There have been many occasions with previous SUVs I've owned, where some very minor issue triggers the "idiot light", but it never affected my ability to use 4wd.

.

 

[Ray Dunakin]

Do you want to pay $100K for a properly designed bulletproof 4Runner? Nobody else does either, which is why they are not built like aircraft.

I don't need it built like an aircraft, but I for damn sure don't need it shutting down 4wd just because of a loose gas cap or an O2 sensor code. That's just plain bad design.

And yes, I also consider this a reliability issue. The whole reason I bought a 4Runner is because I wanted an off-road capable SUV that I could rely on. If any minor, totally unrelated issue, is going to disable 4wd at any time, that is NOT reliable!

 

[wfo9]

Your friend should also look for minor cracks in the exhaust system especially around welds that can allow extra oxygen into the exhaust stream before the rear O2 sensor. These cracks can especially occur from off roading since the exhaust can get hit by rocks and other debris. The change in oxygen content readings due to an exhaust leak can cause a catalyst efficiency failure code along with a variety of other codes. Just something to check into if sensor replacement has not resolved the issue…

As a sidenote, most vehicles from approximately 2006 and newer do not use oxygen sensors in the pre-catalyst positions where 02 sensors were customarily used. Now what is used are air/fuel ratio sensors. The downstream positions are still O2 sensors. The difference between the two sensors is that an oxygen sensor reads precisely that, oxygen only. And air/fuel ratio sensors are capable of measuring the exact stoichiometric air/fuel ratio and can sense the combination of air and fuel in the exhaust stream. This provides a much more accurate reading to the ecm for more precise fuel trim calculations.

Right, the first thing I told him to do was to look for leaks... Also, very familiar with the difference between a WB o2 and a narrow band o2. They both measure A/F ratio via oxygen content.. just within very different ranges. Neither measures fuel.

The old pure narrow band systems worked pretty good for14.7:1. There were a few "lean burn" motors on the market that used wide bands way back in early 2000....

Anyway. my thought is..... if the upstream sensor is off.. It should cause fuel trims to look drastically different between banks...

 

[wfo9]

I don't need it built like an aircraft, but I for damn sure don't need it shutting down 4wd just because of a loose gas cap or an O2 sensor code. That's just plain bad design.

And yes, I also consider this a reliability issue. The whole reason I bought a 4Runner is because I wanted an off-road capable SUV that I could rely on. If any minor, totally unrelated issue, is going to disable 4wd at any time, that is NOT reliable!

Right... It's unfortunate that they made this decision. It's really hard to defend it... Since the same thing can happen once you are already in 4wd.... It's simply a bad design choice. But not much you can do about it besides coming up with mitigation strategies...

 

[SATSTRAIL]

I don't need it built like an aircraft, but I for damn sure don't need it shutting down 4wd just because of a loose gas cap or an O2 sensor code. That's just plain bad design.

And yes, I also consider this a reliability issue. The whole reason I bought a 4Runner is because I wanted an off-road capable SUV that I could rely on. If any minor, totally unrelated issue, is going to disable 4wd at any time, that is NOT reliable!

Holy carp! That is something I was unaware of, and yes it certainly has the potential to be a huge problem for me.

Due to my wife's health issues, I only get one shot per year at taking a "big" 5-day trip, and then I'm far, far from any dealer. Even if I could get it to a dealer it would eat up what little time I have. I will be EXTREMELY pissed if my vacation is shot just because of some piddly error code disabling my 4wd for no good reason. Also, what if the only way out of wherever I am, requires 4wd?

There have been many occasions with previous SUVs I've owned, where some very minor issue triggers the "idiot light", but it never affected my ability to use 4wd.

.

Again, carry a low cost code reader that can clear the stored codes/DTC's for the occurance of intermittent/erroneously stored codes and you will be good go...

For example, you accidentally leave your gas cap slightly loose and it stores an EVAP system related trouble code.... Tighten the gas cap if that was the actual concern and clear the related DTC and you're good to go. If the gas cap was not the actual cause, likely clearing the code will still allow you to continue to travel until the specific test parameter is run again. When it runs again and if the trouble code sets clear the code again. This is all assuming it is not a catastrophic (catalyst damaging misfire or a consistent transmission related failure) drivability failure that caused the DTC to set in the first place. Though those problems do happen from time to time they are relatively rare compared to the intermittent problems that set DTC's on a normal basis that in the short term can be cleared and repairs be addressed at a later time.

 

[Jhalko]

I went from the first page to the last page since I was finishing my snorkel install tonight, but I believe the answer here is that you should buy a Limited, problem solved.

 

[borfoo3]

Again, carry a low cost code reader that can clear the stored codes/DTC's for the occurance of intermittent/erroneously stored codes and you will be good go...

For example, you accidentally leave your gas cap slightly loose and it stores an EVAP system related trouble code.... Tighten the gas cap if that was the actual concern and clear the related DTC and you're good to go. If the gas cap was not the actual cause, likely clearing the code will still allow you to continue to travel until the specific test parameter is run again. When it runs again and if the trouble code sets clear the code again. This is all assuming it is not a catastrophic (catalyst damaging misfire or a consistent transmission related failure) drivability failure that caused the DTC to set in the first place. Though those problems do happen from time to time they are relatively rare compared to the intermittent problems that set DTC's on a normal basis that in the short term can be cleared and repairs be addressed at a later time.

Supporting ^^^this with a true story:

Once upon a time an idiot was off-roading in the middle of the desert and got a CEL. 4wd was already and still on, but limp mode rendered the truck as good as a legless goat..

Normally he would call a tow truck.. but lack of road signs and 100+ ft dunes surrounding him proved this to be impractical..

Cursing his lack of electronic knowledge, he turned to his trusty $20 eBay OBD reader to clear the code, twice, and get himself and his $40k truck home

Did the idiot cause any more damage than what had already happened by doing what he did? He is yet to find out.. Given the circumstance, he knows he'd even press the big red 'void warranty and turn off all electronics' button had that been an option. Either way, the idiot is just glad he did one thing right by having that OBD reader at hand as a last resort..

THE END

 

[007Tacoma]

I'm nobody special. I've been an auto technician for 18 years and 13 years as an ASE/Infiniti certified master technician at an Infiniti dealership in Arizona.

All vehicles no matter who the manufacturer is are required to operate under federal OBD2 operating standards/parameters. There are some subtle differences between the manufacturers but essentially they all operate the same.

The deactivation of the 4wd system on the 4runner due to a stored DTC is definitely a bummer. And bypassing it will not be as simple as creating your own harness to splice it in to the four-wheel-drive control unit. Modern day vehicles are required to operate using a CAN system. This CAN ( controller area network) System operates on a 2 wire 2.5 V low/5V high communication system. The principle is that all control units on the vehicle communicate to each other through these two wires using serial data. The encoded information is sent from one control unit out to all of them but only the control unit that can use the specific data will interpret it and use it. However all control units have to see constant communication with one another. If this communication between control units is lost then U1000 DTC's for the controller area network will be stored in multiple control units and cause issues throughout the vehicle systems.

Since in my experience most triggers of the check engine light are from intermittent issues my first course of action would be to take a code reader that is capable of clearing the DTC. If the issue is intermittent it may not ever happen again ( for example a bug or a piece of debris gets caught on the hotwire of your mass airflow sensor setting a trouble code) and clearing the DTC will get you home. Worst-case scenario you have to clear it a couple of times on your way out. I would like to revert to this strategy rather than hacking into the factory wiring and changing things that may cause significant other issues.

Again I state none of this as fact as I am not a "Toyota expert" however Toyota is required to operate under the same standards and parameters as every other vehicle manufacturer.

This is exactly why I have 2 OBD readers with me at all times. This is excellent information! Thank you!!!

Your friend should also look for minor cracks in the exhaust system especially around welds that can allow extra oxygen into the exhaust stream before the rear O2 sensor. These cracks can especially occur from off roading since the exhaust can get hit by rocks and other debris. The change in oxygen content readings due to an exhaust leak can cause a catalyst efficiency failure code along with a variety of other codes. Just something to check into if sensor replacement has not resolved the issue…

As a sidenote, most vehicles from approximately 2006 and newer do not use oxygen sensors in the pre-catalyst positions where 02 sensors were customarily used. Now what is used are air/fuel ratio sensors. The downstream positions are still O2 sensors. The difference between the two sensors is that an oxygen sensor reads precisely that, oxygen only. And air/fuel ratio sensors are capable of measuring the exact stoichiometric air/fuel ratio and can sense the combination of air and fuel in the exhaust stream. This provides a much more accurate reading to the ecm for more precise fuel trim calculations.

Cracks in the exhaust manifold were the demise of my O2 sensors in my 2003.

 

[proimion]

OK, so I learned that in order to make my 4R more "reliable" I need to bring an OBD tool. I happen to have OBD Fusion on my iPhone and a Carista adapter. Thanks--I actually did learn something from this.

Incidentally, even if the 4R did not have this "problem" I still bring a SPOT Satellite Messenger along with emergency supplies, food, water whenever I go out in the wilds. Oh, and something to fend off bears. Bears are the real threat. The worst thing in life is to be mauled by bears simply because you didn't put on the gas cap correctly.