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AIP Simulation Circuit

330K views 865 replies 94 participants last post by  frankrodrigues12 
#1 ·
I have given up on Toyota engineering a viable solution for the failing AIP system so I started this thread as an open discussion on designing an AIP Diagnostics simulation circuit that will effectively bypass the AIP totally. Most of the information in this post was gleaned from the 900+ post Air Induction Pump thread.

The simulation circuit's should effectively bypass operation of all AIP components including Air Pump 1 (AP1), Air Pump 2 (AP2), Air Switching Valve 1 (ASV1) and Air Switching Valve 2 (ASV2) and do so without setting any diagnostic trouble codes (DTCs). Electrical control for AP1, AP2, ASV1 and ASV2 should be removed to prevent ECM commanded operation, possible failure over time and conflict with the simulation circuitry. The simulation circuit will monitor ECM AIP commanded outputs and simulate the AIDI signal from the Air Injection Control Driver and Air Pressure Sensor signal inputs to the ECM as required for normal operation.

The AIDI simulation circuit will need to produce a pulse width modulation (PWM) signal similar to this design.



The Air Pressure Sensor simulation circuit will need to simulate the exhaust gas pulsation created when the Air Switching Valve commanded output is ON as well as the steady state created when the Air Switch Valve commanded is OFF but the Air Pump commanded output is ON. All states below will need to be simulated.



My time is very limited and I may not get back to this for months. This is an open community effort, so feel free to contribute as inspired.
 
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#777 ·
I'm certainly not against trying it..this thing is way out of warranty and obviously not subject to the extension for newer models. I dont relish spending 1/3 of the car's worth on the dealer to fix the AIP.

From what I can find online, it looks like the yellow/green wire is the THA wire from the IAT that, presumably, needs to be cut and wired similar to the diagram in the AIP override. I can't find a complete diagram anywhere, though, so if anyone can confirm that this is the correct THA wire, I guess I'll be the guinea pig...

Thanks,
Rob
 
#778 ·
That appears to be correct. If the ECU logic works the same as the Gen2 then adding Steve's bypass circuit should disable the AIP pumps. If that works OK you might also want to add the block off plate for the air valve.
Let us know how it works out!
 
#779 ·
From what I can find online, it looks like the yellow/green wire is the THA wire from the IAT that, presumably, needs to be cut and wired similar to the diagram in the AIP override. I can't find a complete diagram anywhere, though, so if anyone can confirm that this is the correct THA wire, I guess I'll be the guinea pig...

Thanks,
Rob

You are correct.
See the pic, and upper right of page 4 of the pdf.

Steve
 

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#781 ·
snip...

The only change I would make to the bypass instructions is to use a 5.6KΩ resistor instead of 4.7KΩ, so that component tolerances do not ever become an issue.

In the wake of Toyota’s warranty extension to the Secondary Air Injection System (the entire system is now covered by a full 10yr/150k mile warranty), this thread has pretty much died. And that’s OK.
snip...
I've yet to make this modification to my 2011 RW but it's still on my to-do list, likely within the next several months, even though I live in dry Nevada. While the extended warranty is nice for most, I travel in some very remote backcountry, where a warranty is of little help if the truck needlessly forces me to hike out the miles I drove in.

I'd be thrilled if Toyota came up with a preventative, permanent fix before I got around to doing this modification, but I'm skeptical.
 
#782 ·
So... Now reading through this thread I see that Toyota has extended their warranty for the AIP to 10 year/150K miles. I am at right about 147Kish miles. I already tried to install the AIP relay and have already taken apart my manifold to clean out the ports/etc. to fix the CEL when it got real bad sometime last year.

My question is... Am I still able to take my truck in under the warranty?
 
#784 ·
My 2005 Sequoia just threw at P2441 and P1445 yesterday at 95K miles.
Hmmm. Mine too...at 81K. Also in San Antonio.

I have been reading this thread for 3-days. Steve and company - amazing dedication!

I believe that somebody posted a wiring diagram for the 4.7L engine. If that is correct, then THA is showing up as the Yellow/Green wire. I am having difficulty locating the valves but I'll keep reading here.

Thanks,
Dave
 
#785 ·
As long as you are under 150K it should be covered. If the CEL is on when you take it in they can verify the problem and fix it.
Probably a 'local' phenomenon...the CEL came on when my wife was driving (2005 Sequoia Limited). She took it right to the dealer who, once the codes were interpreted, proceeded to scare her with tales of woe and huge expense. This was a service adviser. I just spoke to the service manager and he 'doesn't see any reason why they can't honor the warranty extension' on my vehicle. He is reviewing the TSB's now and will call me back with a ruling. Still not out of the woods because my Sequoia is not a Tundra despite the shared components of the AIJ system. <grin>
 
#786 ·
I'm replying to my own post, I apologize.

As many of you have already surmised, Toyota's warranty extension does not apply to Gen 1 vehicles. The local service manager just called back to deliver the bad news.

He claims that it's the same DTC code(s) and the same problem but the parts involved (pumps and ASV's) are 'not the same' as what's in the newer models.

Stuck.

I am having difficulty locating the valves/flanges for the block plate fix and I'm gathering the components for the Bypass today. I have a (back)ordered Haynes manual on the way but it won't be here until the 28th. Is there a real FSM available for the 2005 Sequoia?

Thanks to all,

Dave
 
#787 ·
Dave. Good luck with this. I did this to a 07 with 4.7L engine. The wiring was exactly the same as the 5.7L. I think the wire color was a little different, but it was the same location as the 5.7. I don't know of anyone who has tried this on the Gen 1 but it is worth the try. The parts are cheap and the process is easy to reverse. Let us know if it works. Mike
 
#788 ·
Dave, also, if you go back to my posts on the 4.7, I put some pics in there about the location of the valves for the block off plates. Not sure this is the same as the Gen 1 or not. As for the doom and gloom from the service manager, forget him. This works great. I put about 30K on my truck like this and it worked flawlessly.
 
#789 ·
Dave, also, if you go back to my posts on the 4.7, I put some pics in there about the location of the valves for the block off plates. Not sure this is the same as the Gen 1 or not. As for the doom and gloom from the service manager, forget him. This works great. I put about 30K on my truck like this and it worked flawlessly.
I cleared the 'valve stuck open' codes and limp mode with an OBD scan tool on Tuesday. The next three cold starts did not generate any new codes. I built the bypass and installed it yesterday. The THA lead is green/yellow on the Sequoia 4.7 as well. Now the pumps won't run and there is no reason for the valves to move. I finished the 'pretty' stuff with the installation this morning and you have to look hard to tell that I've been in there.

The 2005 Sequoia only has one pump, but the two valves are in the same location as the Gen2 5.7L Tundras (under the backside of the intake manifold). So that's a pain the in drain. The flanges on the header end are a squeeze, but do-able. I'll be sneaking up on that.

I just want to say again how grateful I am for this resource and for the folks that dedicated so much extra time sharing their ideas, knowledge, and gifts for 'education'.

Salute!
 
#791 ·
Hello
I write from Russia .
I have the Tundra , 2010, 5.7L .
In Russia will soon be winter . Temperatures can drop to -40 C.
I park my car on the street .
I do not like the cold start engine to winter.
For gentle start the engine was installed prestarting heater coolant / EberspacherHydronic /.
The first starting coolant heater.
After 30 minutes of starting the engine.
I have a problem .
As the difference between the outside temperature and the temperature of the coolant composes more than 20 ° C, the error occurs P011B.
This happens every time you start the engine when the coolant is warmed Pre-Heater .
Help me solve the problem.
Can I cheat the vehicle electronics?
How to disable the test two sensors / Engine Coolant Temperature (ECT) sensor and an Intake Air Temperature (IAT) sensor / after 7 hours engine stop, on the error P011B.
Sorry for my bad English.
 
#792 ·
P0011 is a camshaft position sensor error. Are you running 0W20 synthetic oil in your engine??
There were some problems reported with the variable valve timing when cold. 0W20 synthetic oil is supposed to fix that.
 
#796 ·
Code P011B is: "Engine Coolant Temperature/Intake Air Temperature Correlation"

As I understand his concern, when he starts his Tundra while keeping engine warm with a preheater or block heater, the coolant temperature differs from the intake air temperature enough to set this engine code. I don't know how to eliminate the check engine light for this code, but I've had quite a few of these P011B faults and, in my experience, did not affect engine performance.

I have a block heater but have not installed it yet, so I don't know how or if this temperature difference is ignored for those engines with a block heater. Perhaps someone with a block heater can add to the discussion.

Steve
 
#797 ·
The only fix that I can think of is to do the reverse of what the AIP mod does.
That would require a resistor connected in parallel with the IAT sensor instead of in series. The value required is purely guesswork, but something like 10K would be a starting point.
 
#798 ·
The only fix that I can think of is to do the reverse of what the AIP mod does.
That would require a resistor connected in parallel with the IAT sensor instead of in series. The value required is purely guesswork, but something like 10K would be a starting point.
Or some kind of circuit to hold both sensor inputs the same for about 20 seconds, and return to normal after the computer has finished its correlation test.

Steve
 
#801 ·
A long shot, but I wonder if it's also possible to fool the 7 hour timer by starting the engine, then stopping the engine within a few seconds, waiting a short time and starting it again (??).
Knowing Toyota, might also need to remove the key and open and close the driver door before starting it again.

Steve
 
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