P1135 (Yes I've searched lol)

New member here, actual 1st post. New to Tacomas and this forum, definitely not to forums though. I've searched and searched, this forum has already helped me a ton, with wiring diagrams and pictures. Here's what I've run into.......

New to me Tacoma, when I got home with it I hooked up the Launch to it and it had a P1135. I searched the internet and wound up here, found out that it was more than likely a bad air/fuel ratio sensor. Bought a

$146 Denso 234-9001 Upstream Air Fuel Ratio Oxygen Sensor with 10.6” 4-Wire Harness, for Auto Trans Equipped Vehicles

Denso 234-9001 I believe and put it in, cleared the code and it seemed good. Idled for 20 mins with no problem, drove to work later and it came back. Same code, bad heater circuit bank 1 sensor 1so I ohmed it out and it's at 1.4, old one is at 1.4 so neither of them are bad I don't think.

After searching some more I started chasing wiring. Once I found the length of wires going from the top of the transnto the motor and back into the ecm I'm really not wanting to tear that bundle out to check for bad spots. I don't think it's the ecm, would I be ok to just run 4 new wires and tidy them up nicely to where they don't get damaged? Thanks in advance for any help, I'll make a new member thread with pics.

Oh yeah truck is a 2001 Tacoma 3.4L Auto (Prerunner)

 

Many times a poor connection where the sensor plugs into the harness will cause a problem.

Unless the transmission was trying to be removed with the harness still connected.

Broken wires under the insulation or pulled out of pins.

 

@Bivouac

Thank you, I have checked the connections on both plugs, not sure if there are any in that long wrapped up bundle or not. Both seem to be functional, I ran out of time last night but I plan on testing the 3 running from the sensor to the ecm for continuity. If any of them fail that I may just run a new wire(s) through the floor panel up into the ecm. Unless anybody has a better idea

 

All 4 wires going from the sensor to the ecm/evap have solid continuity, hopefully @Bivouac is right and it's a loose connector issue. If not looks like I'm left with needing a new ecm...

 

@Bivouac

I'm still trying to solve this, and just about every single thread that pops up in my search results you're the top poster. So....let me pick your brain if you don't mind.

Ok, I'll start from the beginning and try to keep everything semi-condensed. It's looking more and more like the ECM but I still have some fight left in me lol.

P1135 Heater Control Circuit Bank1 Sensor1
I replaced with

$146 Denso 234-9001 Upstream Air Fuel Ratio Oxygen Sensor with 10.6” 4-Wire Harness, for Auto Trans Equipped Vehicles

Denso 234-9001
Engine light back on after clearing, measured resistance on both sensors heater wires. Both were 1.4 ohms. Started chasing the wires. All connections seem tight, all 4 wires from sensor-plug-ecm have continuity (checked with voltmeter, haven't checked with test light yet), looked at wiring @ evap system under the hood everything looks good, no visible cracking or chafing on white/red wire, checked ground points under hood, all were tight. Happened upon an excerpt from the FSM for this truck, said check voltage between white and white/red wires and body ground for DC voltage and if 9-13 volts replace ECM. I got 12 on both. So according to the FSM it's time for me to replace the ECM. Right now I'm looking for work, and strapped for funds so I'm trying to still repair it if at all possible, if not I'm going to have to wait until I can afford an ECM. Any ideas at all? If it is ECM is anyone familiar with the module, and if so is it repairable?

Thanks in advance for any ideas, whether they help or not lol.

 

What about your fuel trims....are you able to check those...
at idle and Hwy......

IF you've got like + 40 or - 40 that might throw the whole system off...
you would never get stoichiometric combustion....

 

Ok make sure all your connections are clean no bent pins . Even Denso senors fail out of the box you might have received a bad one.

I have had things test fine with the meter the probe pushed through the corrosion ( things looked fine to my eyes) . When plugged together it would not work very much frustration.

That front sensor harness can be damaged if it was not disconnected and was yanked on removing the transmission . Intermittent open circuits due to broken wires

ECM`s can be rebuilt I have not had any done since 2019 I have have no idea what prices are like now.

ECM Depot out of Grand Prairie did my work. You have your part number look for a used one

Unless you had a voltage spike or the ECM got water inside they are pretty tough .

Good Luck!

 

I haven't looked at my fuel trims, I'll check them out here in a sec. I'm 99% sure I can, I've got a Launch Tablet that I use and I haven't even used half of the available options since I've owned it lol. Will report back though, thanks.

 

I don't think the transmission has ever been out of it, but it soes have a salvage title. The guy I bought it from purchased it wrecked and rebuilt it, front end collision tore the whole front clip up. I normally wouldn't have bought a salvage title truck but I was running out of options, lol. Is there any info online about repairing these specific ECMs? If it doesn't look doable I'll definitely pass, but I am decent with electrical work/soldering so I'd at least like to see what was involved. I'll check out your other suggestions here shortly, thanks again man.

 

Go into the scan tool and look at the data when the code was set. Tomorrow at work I will look at the code set criteria for the code to set. From there you can set up some monitors and drive around to see what's happening. You may find an intermittent connection issue at a connector or wire.

 

With out the schematic for the ECM you kinda just guessing . Not to be confused with the ECM pin out.

I have never seen any that I could find

 

I may be postponing the inevitable and end up replacing the ECM anyways, I just feel like that isn't the issue. All of the wiring that I can get to looks great. Few spots where the loom/tape is worn but the wires under it look new, even while bending and stressing them. I can't get to even half of it though, and the likelihood that a wire is damaged or a pin bent seems more probable than the ECM being shot.

2 years ago I would have dove in, found the problem and had it fixed but everything is so weird now. 13 months ago I was in a head on collision and spent 4 months in a coma. When I woke up I couldn't move the left side of my body and 6 months later had to learn to walk again. All things considered I get around pretty good, but nothing at all like I used to. Thinking, walking, talking, wrenching, it's all coming back in different levels but I'd guess that whichever I'm doing the best with, it's still probably only at 80%.

Long story short, I'm trying to figure this out it's just gonna take me a little longer than usual. Lol

 

I can sort of relate no longer being able to walk . One last fall on the ice did me in.

Everything is a brand new learning experience dealing without the strength in my legs.

An hour job is now several .

We do the best we can.
Good luck getting this figured out.

 

If your gonna keep the truck ...forever...

It wouldn't kill you to acquire a backup ecm.

you dont have one of those rare one's....

so it will only cost you $80 ~ $90...at this point in time....

and they will only go up .......

 

@Bivouac I would have never guessed there were 2 of us old cripples in the same thread, haha. No I'm playing, the wreck completely changed my whole outlook on life. 37 years I spent taking a lot of things for granted, hell I still do now although I make a conscious effort not to. But in your own words, we do the best we can. This is how long it's taken me to get the stuff that I said I was fixing to do shortly. I'm getting these screenshots together of the data stream I took, I may get them uploaded before another week has passed ha!

 

Before jumping straight to an ECM replacement... I'd be looking for simple things like vacuum and exhaust leaks.

 

I used to be the man when I was active on the forums, now I can't even upload media lol. Back when I was into this I frequented s10forum, for obvious reasons. Last I remember we used photobucket to upload our pics, I've been trying to upload 11 pics of the data stream I took for like 3 hrs now, I'm about to just type it all out and let y'all decipher what you can.

Andy, I honestly don't see how an exhaust/intake leak could mimic an electrical problem with the A/F Sensor heater circuit. I'll gladly check anything out though just point me in the right direction lol

 

Ok I'm typing this out, not trying to spend all night uploading pics.

2nd Air Monitor. Not Avail
2nd Air Monitor. Compl
AF FT B1 S1. 1.00
AF1 Test. Compl
AF2 Test. Compl
AFS B1 S1. 3.3
AS Test. Compl
Catalyst Monitor. Avail
Catalyst Monitor. Incomplete
Coolant Temp. 186.8
Cylinder # Misfire Count. (Cyl 1-6 all at zero)
EGR Monitor. Not Avail
EGR Monitor. Compl
EVAP Monitor. Avail
EVAP Monitor. Incompl
EVAP VSV. OFF
FC IDL. OFF
FC TAU. OFF
Fuel Pump. ON/H
Fuel SYS #1. OLFault
Fuel SYS #2. Unused
Fuel System Monitor. Avail
Heated Catalyst Monitor. Not Avl
Heated Catalyst Monitor. Compl
IAC Duty Ratio. 41.84응
IDL SIG. ON
IGN Advance. 9.50 deg
IGNITION. 492
Injector 3.07
Intake Air. 82.4degree F
Lock UP SOL. OFF
Long FT #1. -0.81
Low. OFF
MAF. 3.98gm/s

MIL Status. .ON
Misfire Load. g/rev
Misfire Monitor. Avail
MISFIRE RPM. 0 rpm
02FT B1 S2. 99.16
02S B1 S2. 0.07V
02S(A/FS) Monitor. Avail
02S(A/FS) Monitor. Incmpl
02S(A/FS)HeaterMonitor. Avail
02S(A/FS)HeaterMonitor Compl
Overdrive Cut SW1. OFF
Overdrive Cut SW2. OFF
OXS1 Test. Compl
OXS2 Test Compl
PNP SW. ON
PS Oil Press SW. OFF
PS Signal. ON
Purge VSV. . . CLOSE/OFF
Reverse. OFF
Shift. 1st
Short FT #1. -0.03%
SPD(SP2) mph
Starter SIG OFF
RRRR
Stop Light SW. OFF
Throttle Pos. 9.41
TOTAL FT #1. 1.01
Vapor Press VSV. ON
Vapor Pressure. 0.17 psi




Alright guys. Did a live stream with every single option selected, so of course I had to leave a few out. If anyone is familiar enough with these readouts feel free to chime in

 

I just had to repair a P1135 problem using the local stealer shop. Couldn't get into the independent shop for T/S for two weeks, so the dealer was the only option. CELs on the dash are very misleading. Anyway, had I been able to get the nuts off the air-fuel sensor I could have saved $110 diagnosis fee and $329 for a sensor that Amazon sells for $129 toyota p/n89467-35011.

.

 

So the 1135 is directly related to the heater circuit. So not to be an ass, but everyone else telling you to verify no exhaust leaks and no vacuum leaks will just have you chasing your tail. The sensors ability to heat has nothing to do with those things and will only make you pull your hair out. If you've done your tests via the service manual diag procedure and you have voltage where you're not supposed to, replace the component (in this case, the ECM) and move on. If the sensor ohms good, you have good continuity between the sensor and ECM, then you're basically stuck with a bad ECM. Don't over think it .