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

[wfo9]

Yea, I did not really want this to be a "it is a bad design" thread. I think it is a bad design, but no point in *****ing about it. Toyota sees the 4wd system as non critical and treats it as such. Not ideal, but it is what it is... Take the good with the bad.

Just need to find a way around it.

I've had the ADD actuator in my hands several times.. just did not realize that it was disabled when the gas cap was loose at the time... so spent no time understanding it. Next time the skids are off I'll do some poking around to see how hard manual activation is mechanical or via wires... I think that would be a good enough solution to have in my back pocket. If that is not possible a wiring hack may be necessary.

 

[ToolUser1]

Which proves my original point. Because there's little redundancy built into the average vehicle it's even more important to have well thought out failure modes. Simply shutting off unrelated systems leads to unnecessary and potentially dangerous loss of functionality.

And just a friendly observation - insulting my intelligence rather than focusing on the technical merit of my observation isn't very conducive to a friendly conversation.

Done with this thread, and now I miss my 3rd gen even more.

...which goes to show how little you know about complete systems. When certain components fail on say, an aircraft, there is redundancy built in. In addition to redundancy, there are other systems that shut down to keep from messing up other components. 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.

 

[007Tacoma]

There are several PIDs you can look at to see if the seller is resetting before you test drive. If it's low or zero (like it was in your case), you can confront the buyer about what's up and/or look into it further.

https://en.wikipedia.org/wiki/OBD-II_PIDs#Mode_01
Mode 1, 30: Warm-ups since codes cleared
Mode 1, 31: Distance traveled since codes cleared
Mode 1, 4E: Time since trouble codes cleared

I fixed the problem by no longer buying used vehicles, but that is still really good information. :thumb:

 

[e60ral]

if you want to be able to bypass the 4wd ECUs ability to not engage the ADD look over at the rocksolidtoys forum. there is a write up on how to wire the ADD up to be switch controlled and not go through the ECU. now it will only work with the manual Tcase. if youre going that far you might as well just go all out on it and finish pinning it out and fully get rid of the 4wd ECU, youd still have the lights in the dash work, but youd also have to put the factory locker on a new switch as well and youd totally lose atrac, but who uses that anyway.

or you could just get a v8 4th gen and not have the ADD or a lot of other sensors to worry about.

is this sarcasm? atrac is great, are there people who never use it? Its obviously not for every situation, but my default is to turn it on as soon as I'm in 4L and only turn if off as conditions dictate

________________________

I also have a ScanGauge and can clear codes on the go, but a way to switch the ADD without completely bypassing the ECU would be good

 

[honda250xtitan]

Your thread title is nothing but click bait.

Looking at who posted the thread regardless of thread title caused me to click it. Changing his username will solve the clickbait issue. I read EVERYTHING OP posts. lol but really.

 

[007Tacoma]

[MENTION=106176]wfo9[/MENTION] ...so, would the end product be best described as an ECU bypass that will allow the ADD, Locker, and TCase to be engaged while bypassing the "please take to your dealer because ______" light?

I would think that there could be a way to splice in your own "redundancy" harness, but I would need to see a technical manual to come up with such a thing.

 

[flyrv9]

When we bought our Tundra in 2000 I sent in the tear out card at the back of the owners manual with $75 and purchased a full set of manuals. That and a $35 code reader from Pep Boys has allowed me to diagnose and repair 2 O2 sensors and 1 coil pack. Not bad for 18 years and around 150K miles. So, yea a code reader is a good, cheap tool to have - home or away. I would have liked to have been able to purchase a set for the 4Runner - but Nashman's link will do just fine. (see the stickies).

1Engineer is correct in his aircraft analogy. Having spent 20+ years working on avionics, electrical & instrumentation systems in a flight test environment, I can confirm there is a connection between functionality, reliability and what the end user sees.

The whole idea is to let the pilot do their primary function - fly the airplane. Even with all these new automatic systems, flying the airplane is still number 1. It used to be (for example) if a display failed there was a switch to switch (revert) that display's function to another display. Newer systems switch automatically. Sure the pilot could still do it the old way - but what if he was real busy at the time on short final with a killer crosswind at night during a thunderstorm. Therefore some aircraft system faults are never seen by the flight crew. They do however, show up to maintenance and are dealt with during normal maint checks.

 

[007Tacoma]

When we bought our Tundra in 2000 I sent in the tear out card at the back of the owners manual with $75 and purchased a full set of manuals. That and a $35 code reader from Pep Boys has allowed me to diagnose and repair 2 O2 sensors and 1 coil pack. Not bad for 18 years and around 150K miles. So, yea a code reader is a good, cheap tool to have - home or away. I would have liked to have been able to purchase a set for the 4Runner - but Nashman's link will do just fine. (see the stickies).

1Engineer is correct in his aircraft analogy. Having spent 20+ years working on avionics, electrical & instrumentation systems in a flight test environment, I can confirm there is a connection between functionality, reliability and what the end user sees.

The whole idea is to let the pilot do their primary function - fly the airplane. Even with all these new automatic systems, flying the airplane is still number 1. It used to be (for example) if a display failed there was a switch to switch (revert) that display's function to another display. Newer systems switch automatically. Sure the pilot could still do it the old way - but what if he was real busy at the time on short final with a killer crosswind at night during a thunderstorm. Therefore some aircraft system faults are never seen by the flight crew. They do however, show up to maintenance and are dealt with during normal maint checks.

It is also a matter of cost. As mentioned before (@1engineer), we don't pay 6 figures for a 4Runner that may leave you stranded but relatively safe. As opposed to a plane that could have a less than desirable outcome if something fails or is disabled without redundancy.

 

[SATSTRAIL]

That may not work... but is a good suggestion to try for intermittent stuff. Many of the test run on each startup...

The catalyst efficiency system test run by the ECM typically requires a drive on the freeway or at least speeds greater than what you would be doing while 4 wheeling out in the back country. EVAP tests also do not run on every start up. Virtually every OBD2 system monitor test requires a specific drive cycle for it to test for failures. So in most cases clearing the code will usually work until that test runs again. An open/shorted wire can cause a more immediate failure code to store because rather than using a rationality logic to see if something is operating within parameters, it uses normality to do an immediate go/no go test for the system. Wire opens/shorts are pretty rare compared to a sensor failure.

 

[surfbm]

I disagree completely. Designing failure modes that simply cause _everything_ to stop working, without regard to safety or system impacts, is lazy engineering at best. Where I work it would get you fired pretty quickly.

The failure of an 02 sensor has no impact on either operator safety or system integrity, so having it trigger a cascade of unrelated failures is simply not acceptable. Think of it in terms of an aircraft or a spacecraft and you can quickly see how poorly this design philosophy translates to the real world.

If it's true, it's such bad engineering it would be grounds for moving away from Toyota. I'll need to perform some tests to confirm.

Jeeps do the same thing. Not sure about the Wranglers, but i went for a test drive of a grand cherokee 6 months ago, and couldnt shift to 4wd because the battery voltage was low and throwing a code...

 

[1engineer]

When we bought our Tundra in 2000 I sent in the tear out card at the back of the owners manual with $75 and purchased a full set of manuals. That and a $35 code reader from Pep Boys has allowed me to diagnose and repair 2 O2 sensors and 1 coil pack. Not bad for 18 years and around 150K miles. So, yea a code reader is a good, cheap tool to have - home or away. I would have liked to have been able to purchase a set for the 4Runner - but Nashman's link will do just fine. (see the stickies).

1Engineer is correct in his aircraft analogy. Having spent 20+ years working on avionics, electrical & instrumentation systems in a flight test environment, I can confirm there is a connection between functionality, reliability and what the end user sees.

The whole idea is to let the pilot do their primary function - fly the airplane. Even with all these new automatic systems, flying the airplane is still number 1. It used to be (for example) if a display failed there was a switch to switch (revert) that display's function to another display. Newer systems switch automatically. Sure the pilot could still do it the old way - but what if he was real busy at the time on short final with a killer crosswind at night during a thunderstorm. Therefore some aircraft system faults are never seen by the flight crew. They do however, show up to maintenance and are dealt with during normal maint checks.

I have a bit of experience on both aircraft and simulator hydraulics system design... suffice to say the redundancy is more expensive than the primary!
The 4Runner, in some ways, is designed to protect the vehicle from further damage. There is no redundancy but there is protection, hence the shut down of systems.

 

[Leucifer]

Yea, I did not really want this to be a "it is a bad design" thread. I think it is a bad design, but no point in *****ing about it. Toyota sees the 4wd system as non critical and treats it as such. Not ideal, but it is what it is... Take the good with the bad.

Just need to find a way around it.

I've had the ADD actuator in my hands several times.. just did not realize that it was disabled when the gas cap was loose at the time... so spent no time understanding it. Next time the skids are off I'll do some poking around to see how hard manual activation is mechanical or via wires... I think that would be a good enough solution to have in my back pocket. If that is not possible a wiring hack may be necessary.

I get what you're aiming for, overall. The base issue is that Toyota's stock set-up is aimed for what I call the "lowest common denominator".... i.e. the soccer mom who really doesn't know any better, has an issue, and the system disables it to minimize damage to the system.

It's a problem though for "enthusiasts" who have at least half an idea what they're doing, and maybe NEED to override in order to get out of trouble. Murphy's Law being what it is, sh*t always goes wrong at the most inconvenient times, and it's nice to at least know ways to at least temporarily get around a problem.

So, it's not so much an issue of "bad design". It's more of an issue of Toyota built the fail-safes with a low-end user in mind.

That said, it'd be nice to have some way to override if you were in a pinch. Even if it contains a whole spreadsheet of "be aware, doing this may render X warranties void." I mean, hell.... as soon as you do a lift, you're potentially voiding OEM responsibility on a whole mess of stuff. Why not let the buyer decide if they want to take that one step further?

I do agree with 007Tacoma though, I'd want a look at a tech manual before taking a crack at coming up with a workaround or bypass. There's so many ways this could go badly.

 

[BLACK-FL4RUNNER]

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

Solid Axle Swap.

Done. :welcome:

 

[CruzadoBlanco]

is this sarcasm? atrac is great, are there people who never use it? Its obviously not for every situation, but my default is to turn it on as soon as I'm in 4L and only turn if off as conditions dictate

________________________

I also have a ScanGauge and can clear codes on the go, but a way to switch the ADD without completely bypassing the ECU would be good

not at all. and my ATRAC is automatically turned on when i lock my center diff, but between my suspension travel and my rear locker that i can engage no matter if im in 4lo or not my ATRAC never actuates. i could take it or leave it. it also comes from me learning how to wheel in a no frills wrangler and having to learn how to use the brakes and parking brake to get the traction where i needed it combined with the LSD in it.

also now that im back with a bare bones solid axle truck all i get is gearing, differentials, and foot work to get over obstacles. ATRAC is OK for most people but if your going so far as to bypass parts of the 4WD ECU to retain other functions then ATRAC is probably the last thing your worried about.

 

[e60ral]

Oh, too cool for gadgets. I am too actually I replaced my windows with manual because that's how I learned and disconnected my ABS because my no frills first car didn't have it

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[wfo9]

The catalyst efficiency system test run by the ECM typically requires a drive on the freeway or at least speeds greater than what you would be doing while 4 wheeling out in the back country. EVAP tests also do not run on every start up. Virtually every OBD2 system monitor test requires a specific drive cycle for it to test for failures. So in most cases clearing the code will usually work until that test runs again. An open/shorted wire can cause a more immediate failure code to store because rather than using a rationality logic to see if something is operating within parameters, it uses normality to do an immediate go/no go test for the system. Wire opens/shorts are pretty rare compared to a sensor failure.

I think you are correct here.... I talked with my buddy and he was actually able to get the dash lights to go off with a battery disconnect. However, the lights would come back on after he went over 40mph... In his case it was a CAT efficiency code. He was afraid to use the battery disconnect technique to engage 4wd because he was afraid he would not be able to go back to 2wd to get home once the MIL set again... I'm almost sure it would not stop you from going back to 2wd... But I understand why people get confused and concerned about the mystery of modern vehicles.

So, this may be a viable technique for many of the intermittent benign MIL codes.

I would like to test this out, but I have not come up with a good way to simulate. I figured disconnect the downstream o2, but that might fail right on startup (like you said).... I basically want to throw in a bad rear 02 and see what I can do in term of 4wd...

 

[wfo9]

not at all. and my ATRAC is automatically turned on when i lock my center diff, but between my suspension travel and my rear locker that i can engage no matter if im in 4lo or not my ATRAC never actuates. i could take it or leave it. it also comes from me learning how to wheel in a no frills wrangler and having to learn how to use the brakes and parking brake to get the traction where i needed it combined with the LSD in it.

also now that im back with a bare bones solid axle truck all i get is gearing, differentials, and foot work to get over obstacles. ATRAC is OK for most people but if your going so far as to bypass parts of the 4WD ECU to retain other functions then ATRAC is probably the last thing your worried about.

I think they improved ATRAC quite a bit on the 5th generation/150 platform. I still see it screw up often... and much prefer the control of lockers... I've seen it do really stupid stuff on the 120 platform. To the point that I would simply not use it. Might be related to tire size or something....

 

[SATSTRAIL]

I think you are correct here.... I talked with my buddy and he was actually able to get the dash lights to go off with a battery disconnect. However, the lights would come back on after he went over 40mph... In his case it was a CAT efficiency code. He was afraid to use the battery disconnect technique to engage 4wd because he was afraid he would not be able to go back to 2wd to get home once the MIL set again... I'm almost sure it would not stop you from going back to 2wd... But I understand why people get confused and concerned about the mystery of modern vehicles.

So, this may be a viable technique for many of the intermittent benign MIL codes.

I would like to test this out, but I have not come up with a good way to simulate. I figured disconnect the downstream o2, but that might fail right on startup (like you said).... I basically want to throw in a bad rear 02 and see what I can do in term of 4wd...

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.

 

[(none)]

I think they improved ATRAC quite a bit on the 5th generation/150 platform. I still see it screw up often... and much prefer the control of lockers... I've seen it do really stupid stuff on the 120 platform. To the point that I would simply not use it. Might be related to tire size or something....

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.

 

[e60ral]

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

Solid Axle Swap.

Done. :welcome:

They said reliable not capable, show me a SAS that is remotely as reliable as leaving things stock

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