Throttle position sensor location?

Hello,

Could anyone please post a picture/link on where the throttle position sensor is on a 2005 Tacoma, 4.0/6 cyl, 4WD? Even the part number will give me a solid lead on finding a diagram for it.

I've searched for hours and hours finding nothing but Gen1 and Gen3, and a lot of links from old forum posts are now dead.

Thank you!



The back story for those interested:

My Tacoma (2005, 4.0, 4WD, about 135,000 miles on it) has been acting up lately when shifting gears. Acceleration feels weak, and the point when it's shifting gears seems to take a bit longer around the 35-40mph mark. Normally when I press the pedal, I hear and feel a corresponding output. Lately if I press it, it will just sort of drone on and not react as quickly. I need to hold it there for some time before the gear will change and I can resume normal operation. It's to the point where I wouldn't trust it weaving through lanes on a highway.

There have been 2 times so far where after I thought the gear had shifted (according to my driving habits of this truck in the past 6 years), I pressed the pedal and it sounded like I was flooring it even though I was just pressing lightly/normally in a 30-40mph speed limit area. The engine reved up very loudly and didn't go any faster. Oddly the RPM needle didn't seem to jump beyond around 2.

A small shop said transmission needs to be replaced because "pressure numbers don't look right" after 5 mins with the OBD2. I don't have several grand just waiting to be burned on a transmission swap on a 5 minute diagnosis. So I took it to a professional transmission shop for a second opinion.

The professional transmission shop had it for 2 days, test drove it, found absolutely no issues related to transmission, pressure was fine, readings were fine. My feeling is they took a "no code, no problem" approach.

On my way out of the transmission shop's parking lot, as soon as I hit the road I feel the weak acceleration. I know they don't know my vehicle, but how do they not feel that they have to hold the pedal down a really LONG time before gear change? So I had a friend test drive it, they felt what I was talking about almost right away, and they don't know my vehicle either.

Bottom line is: I'm going to have to fix this issue myself somehow.

I need to check:
1. MAF sensor
2. Throttle position sensor
3. Maybe clean/check the throttle body
4. And any other suggestions you guys might have

The transmission fluid is also probably due for a change. I bought the truck used at 101k miles and am unsure what sort of maintenance the previous owner did to it. Is that something that would have been changed during the frame recall?

 

Personally, I would start with spark plugs and see what happens

 

This should help you find the correct part numbers, than look at Rockauto.com for good pricing.
http://densoautoparts.com/find-my-part

 

Pedal position is on the pedal. Throttle position is on the throttle body.

 

Hard to say what it could be without putting eyes on it, but you don't have a traditional TP sensor, the truck is drive-by-wire, there is an APP sensor (gas pedal) and then the motor controlled throttle assembly, which has it's own position sensor in it.

If you think the lack of power is throttle response related, you need to find somebody with a scan tool that can graph the correlation between the two sensors and check for glitches or drop-outs.

But you do need to start with the basics, especially if you don't know the service history.

 

Thanks for the input guys,

The spark plugs were changed out, they'll be 2 years as of this April, though I won't rule them out. Went with 6x Denso (3381) K20HR-U11. All my research at the time showed that there was no harm in putting all 6 plugs of the same brand/type, despite the stock plugs being 2 different brands, with the left being one brand, while the right was another. It's been running fine on them for nearly 2 full years. This all started happening about 3 weeks ago. No maintenance or other changes were made to the vehicle at the time this all started.

 

Sounds similar to what I've been experiencing (2013 4wd, 109k). Cruising between 30-40mph, noticed some hiccups a while back. Of course it went away before the mechanic took a look at it. No codes either.
Now I'm just dealing with a sluggish response around 40mph.
Here's a list of the things that I've tried.

• Throttle body cleaned
• MAF cleaned
• Plugs checked and gapped
• AT fluid flush
• Differential fluid flush

Read another post somewhere that mentioned TPS (Throttle Position Sensor) and Shift Control Solenoid as a potential culprit.

Hope this helps in some way.

 

Hi steveyosh, sorry to hear you're going through this too.

So far I've cleaned the MAF sensor, no luck.

You know, I had totally forgotten to consider the engine air filter. Have you tried changing that? Something so simple and basic, it went right under my radar. Mine is actually pretty old and WAY past its change date vs recommended change intervals. The replacement should be here tomorrow.

If that doesn't work, I will try changing the speed sensor. If that doesn't work, on to whatever else I can find...

 

Hey Zot,

Yah I changed the air filter and it made no difference.
It's one of those problems that others wouldn't know exist. I think we notice because we drive it day in/day out. I just know it's not driving normal and bugs the hell out of me not figuring it out!

 

I realize this post is a few months old now, but I figured I'd update it for those still searching and trying to rule things out like I was for months on end...

The short version is: I have a bad valve body in the transmission. Shop wants $950 + tax to fix.

As time has passed on, the problem seems to have shifted when it occurs, and gotten worse. It no longer happens around the 30-40mph area with weak/no acceleration, it now happens around the 1-5 mark with a hard jolt. This seems to only occur if I go at least 30mph before attempting to make a stop. I suspect what happens is it is in the process of downshifting and it gets delayed due to the faulty part, and when I hit the gas it's fighting itself. They could be unrelated, but problem A disappeared exactly the same day problem B showed up, both dealing with acceleration, so I don't know how else to take that.

What happens now is say I'm approaching a red light, I'm JUST about to stop, but it goes green, so I might still be going 1-2mph or settling into the stop before your body feels the inertia of the stop. I hit accelerate and it jolts. Not every single time, but often enough to make me wary of trying to get out of a parking lot on a busy highway in a hurry. The force varies from a love tap to where it's like I get back-ended by someone. The first time it happened was at night, I honestly thought someone ran into me, but didn't see any lights behind me or vehicles, nobody was there. Tires let out a massive screech when that happened too.

I think it's time to let it go. Getting another vehicle will hurt a lot up front, but it's better than dealing with the stress and costs of critical repairs every 3-4 months.

 

Might be able to find a good used transmission cheaper and just slap it in yourself.

 

From a later year too. I believe the automatics were the same for all 2nd gen.

 

Thanks for your post Zot!

Your symptoms sounds exactly like what I'm going through. It's evolved as time went on. First started w/ some hiccups. Then went to sluggish response. And lately add some occasional jolting, like you said. It's as if the truck is indecisive on what it wants to do, shift down to stop or to stay in gear and go. I've been accepting of my situation since it doesn't bother me too much anymore. But when it does, and I take it to a mechanic, at least I can have a direction to point to.

Thanks again.

 

$950 isnt all that bad considering labor costs nowadays. I had a '97 GMC Sierra back in 2005 where the 1-2 shift felt like someone rearended me whenever the trans got to operating temp. Luckily my retired mechanic dad specialized in automatic transmissions. He did some reseach and found that there was spring in the valve body that would prematurely wear (something to do with the "cushioning" between shifts), and the fix was to install a 2 inch long steel dowel in its place. We pulled the valve body, replaced the spring, and the truck was good to go.

My point is that an issue with the valve body isnt all that bad, and is not likely to have caused permanent damage. Changing it out or replacing a component will likely get you many more miles out of the truck.

 

This will most likely be my final update to this thread, unless there are comments/questions that require response. Since the subject line and actual issue are now quite far apart, I don't want to essentially derail my own thread, though it has been great for troubleshooting, and in a roundabout way, guided me to a final resolution.

While I'd love to just leave my problems behind, it's just not practical at this time, so I decided to go with the repair.

Repair breakdown:

1x Valve body repair kit - $194.21
1x Filter kit - $24.80
1x Line pressure solenoid - $242.13
6x Liter Toyota transmission fluid - $47.58 ($7.93ea)
5.5x Labor - Remove and replace transmission oil pan and valve body assembly. Install parts listed. Fill fluid and road test. $440 ($80/hr)
8.75% tax

Total: $1031.73

There were 2 diagnostic fees as well, I think $55 and $75. They couldn't find the issue the first time so I figured maybe it wasn't the transmission. But then the symptoms changed as mentioned in my other post. The second time I personally drove them around and recreated the problem because they still insisted there was no issue.

Ecoterragaia, I think you were heading in the right direction with what you said. I tried asking the mechanic what went wrong, because I naturally just like knowing what makes things tick and how they work. He wouldn't go too deep into the details but basically said aluminum parts wore out, I think he also said something about bores, maybe that's what the kit was for. I bought this truck in 2012 (it's a 2005), the previous owner had a trailer brake controller installed, so who knows what they were hauling or how they treated it, and if they ever properly serviced the transmission fluid during that time. They had it for a little over 100k miles. It's now sitting at 138k.

In terms of the repair, it seems to be a success. Repaired on June 26th, and it's now July 6th. Not a single jolt since the fix. That's 11 days straight of 0 issues. Before, it was a good day if it only jolted 1-2 times a day. While I'm not happy with dropping such a huge chunk of cash so abruptly, I am somewhat breathing a sigh of relief being able to drive like normal again, which I haven't been able to do since mid February.

I appreciate all the help that everyone contributed here. Thank you!

Next up: Changing out severely rotted power steering lines and then a total A/C overhaul because the compressor most likely grenaded (loud grind, clogged system). See you guys in other threads.

 

Omg, I have the exact same problem with same vehicle. Sluggish throttle response. Can push gas pedal and get past it. If im very light on the gas pedal it doesn't do it. Almost feels like a miss verses trans slip. Good yota mechanic and trans mechanic claim not to notice when test driving. Throwing no codes. Tried fuel system cleaner, new plugs, cleaned throttle body, serviced transmition. Occasionally I feel a slight bump when comming to a stop. Did the valve body repair hold true? Im at the point of just dealing with it verses continuing to throw money at it. Im like you though, it's driving me nuts! Still need to clean my mass airflow sensor. Thought about installing aftermarket TPS. $175. Wasn't aware there's a pedal sensor. You'd think it would throw a code. I also came across web site sighting TPS and shit solenoid as possible culprits on these vehicles with 100k plus miles.