Secondary Air injection Solenoid BYPASS

DirtinLa

Original poster
Member
Dec 27, 2016
20
Gonzales La
Greetings Everyone,

I have a newly aquired 06 TB 4.2 that is throwing the dreaded 2440 and 410 codes

I have fully explored the issues. Understand the whole system and know why and how

it works. I have pulled and cleaned the solenoid.

HERE IS MY QUESTION

I see on the Toyota site they reference what they term as a SAIS bypass. They are tricking

the PCM to believe the solenoid is working.

I have a 5/6 wire plug on mine not the 2 wire. I understand there are 6 wires;

(1)low reference (2)Control (3)volt reference (4)ground (5)N/A (6)supply voltage

If anyone knows what the pcm is seeking on each wire we can fool it to believe the

solenoid is working.

Anyone interested in helping with this project?

Thanx in advance

-=Fred=-
 

jeffro312

Member
Oct 4, 2012
442
East Haven,Ct
Not sure about the method you are talking about. When I bypassed my sais I sent ecu to pcmofnc to program sais code out then removed solenoid and installed a block plate I got from dealer and removed sais pump
 

Mooseman

Moderator
Dec 4, 2011
25,262
Ottawa, ON
Like @jeffro312 said, that is the usual method but I think he's looking at another way to fool the PCM without having to tune out the codes. The secret would be to find out what signals the PCM is looking for when it's activated and deactivated. May be beyond normal capabilities or may need an oscilloscope or meter the wires on a working system.
 

Mooseman

Moderator
Dec 4, 2011
25,262
Ottawa, ON
I doubt it. Much more that happens with the SAIS.
 

AtlWrk

Member
Dec 6, 2011
674
Besides cleaning the solenoid how much testing of the system have you done? Could be something cheap and easy like the solenoid relay...

To directly answer your question: in 2006, the SAIS system added an air pressure sensor to directly monitor the SAIS system operation in three stages:
pump on, valve open
pump on, valve closed
pump off, valve closed

If the feedback from the pressure sensor is wrong during any of those stages the PCM will assume a malfunction (pump not working, valve stuck, etc.). It's theoretically possible but is going to be way way more complicated than just jumping the connector with a resistor. You're only real options IMO are diagnosing/fixing it, or removing it and having the code tuned out.
 

DirtinLa

Original poster
Member
Dec 27, 2016
20
Gonzales La
I know that there is a bypass for the SAIS for the Toyota
just Google toyota sais bypass and they sell it as a plug and play along with a block off for the solenoid. Hewitt-tech is the comany selling it.
I have been trying to find out how they did it as many forums state there is info on a DIY fix posted online. After searching though I can't seem to loacte the DIY, only the plug and play they are selling.

The issue I am having is I am getting code after code and seem to be tracing gremlins.

The one consistent code is P2440

I replaced the relay... verified the pump is fully operational.
I had no major water in the sytem.
I removed the secondary air solenoid and cleaned it thoroughly and checked to be certain the valve opens and
closes when voltage is applied to it but still immediately receive the p2440.

I am really thinking it may be a ground problem so before I go and throw a hundred dollar part at it I'm going to check my G201 ground connection. That is where the solenoid grounds. If it has a bad ground it may be getting improper voltage as well as throwing other erratic codes.

Thanx everyone for your help and I let you know what I find.
 

DirtinLa

Original poster
Member
Dec 27, 2016
20
Gonzales La
I spoke to the guys at Hewitt. They said they are tricking the PCM into believing the solenoid valve is there and working. They also state their system may very well work on the trailblazer but I would have to buy one to try it. BUT their system is more than the GM part.

They said probably the pressure sensor has failed in mine OR the valve has a min'ute leak in the valve itself.

I checked the leakage of the valve on mine and it was tight... not leaking at all as far as I could tell. He said to block off the valve completely and that would let me know if the pressure sensor had gone out.

Anyone know how to make that sensor "think" there is actually pressure there?
 

AtlWrk

Member
Dec 6, 2011
674
Which relay did you replace? The large one on the pump itself, or the one in the fuse block for the solenoid (#55)? Also, the ground for the solenoid is G107, on the driver's side of the engine block. There are 3 or 4 in that area that are known trouble spots for causing all sorts of erratic behavior (the ignition switch is another common source of electrical gremlins).

P2440 specifically points to a short to ground on the solenoid relay (#55) control wire (erroneously commanding the solenoid open). Easy check: turn your key to run (no start), wait a minute or two, then pull Fuse #54 (AIR SOL). You should not hear a relay (#55) or the solenoid click when you pull the fuse. The point being that it may not be the solenoid itself, but the wiring and/or control circuits for it.

Fortunately, in 2006, they added half a dozen new DTCs for this system to be more specific about the fault found. On the flip-side, there are also many more things the PCM is checking for making it harder to fool with a simple "bypass".
 

DirtinLa

Original poster
Member
Dec 27, 2016
20
Gonzales La
Which relay did you replace? Sorry not a relay
I replaced the vent valve solenoid... p0449 mine wouldn't click when I applied power to it

I stand corrected on the grounds. I'll climb underneath hopefully tonight and see if I can find those grounds.

I'll also do the fuse pulling tonight as well.

I'll let y'all know

Thanx in advance
 

DirtinLa

Original poster
Member
Dec 27, 2016
20
Gonzales La
I pulled fuse 54 after leaving the ignition on and I heard and felt the valve clicking

in the secondary air solenoid valve. No clicking in the #55 relay

I read codes after starting and I had three pending codes at that point...

P0496
Evaporative Emission (EVAP) System Flow During Non-Purge

P0418
Secondary Air Injector Relay A Malfunction

P0412
Secondary Air Injection Switching Valve A Circuit

I cleared the pending codes and then after 2 restarts no set or pending codes.

So what does all this mean?

Thanx in advance

-=Fred=-

p.s. It's dark so I'll have to check the engine grounds at another time
 

AtlWrk

Member
Dec 6, 2011
674
P0418 and P0412 probably set when you pulled the fuse. The P0496 is probably not related...but keep an eye on it if comes back.

No clicking from the #55 relay with clicking from the solenoid tells me the relay has failed closed (likely welded its contacts together). Good news is that's about as easy a fix as it gets for something like this and explains the P2440.

Swap it with relay #40 (Horn). If the horn starts sounding on its own you know the relay is toast. If not, try the horn with the relays swapped--it may be sticking but not permanently welded contacts. (Or just replace the suspect relay #55).

If that's not it then there are still a few more possibilities but they're much less likely--so we'll cross that bridge if we have to...
 

AtlWrk

Member
Dec 6, 2011
674
Great news and thanks for reporting back! Gotta love when it's an easy and cheap fix like that (called it in post #6 BTW :celebrate:).
 

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