This is the self destructing transmission edition. (roughly 175,000 miles)
Recap: Transmission got stuck in limp mode with a high side driver circuit low voltage code so I had the techm replaced and it started working good again. Couple days after the shuddering begin.
Up until now I’ve been living with the shuddering. This morning on my way to work I went to overtake someone on the highway. I pressed the pedal down to pass as you normally do when you want to pass someone and the vehicle lurched forward then immediately all power was gone. Check engine light. “Service stabilitrak”, “Service Traction Control” “Reduced Engine Power Mode”. Won’t rev past 1500 RPM. I was already 95% of the way to work so I just rolled in. It absolutely ran like crap and the acceleration it did have didn’t feel smooth at all. It will shift into park, neutral, drive, reverse and each of the low gears just fine. The reduced power mode just won’t let it go past 10-20mph tops.
Before I sell this for parts is there any other possibility worth looking into that could cause these particular symptoms or does it sound certain that the transmission quite simply grenaded itself? Would I be wasting my time and money by getting a scan tool and looking to see if there’s some sort of throttle control codes or something? Before I got the transmission “fixed” the last time I took a gander at the throttle and noticed it was pretty dirty. Just a note, probably not relevant. I don’t know it’s been a very bad monday.
On this model I believe it’s integrated in with the throttle body, may be wrong on that though. Certainly be a lot cheaper than getting a new vehicle though.
At what speed was the shuddering happening?? Normally that is when the torque converter is locking up, when the pressure plate is engaging and like a manual transmission pressure plate and flywheel having hot spots it will shudder while engaging… A little more complicated but that is the jest of it…
Sounds like yours is going into “Limp Home Mode” and that is why you are having reduced power and the Transmission should be “stuck in one gear” and that is so you can get it to a repair shop without doing anymore damage…
Like TXdealer stated, you need to read the codes 1st and go from there…
Before it was going into limp mode. That’s where it was limited to one gear. But I could still rev the engine as high as I wanted. Now the computer is limiting me to 1500 RPM. It says “Reduced power mode” on the dash and it didn’t do that with limp mode.
I’ll certainly be reading the codes though. Thanks for the input guys.
Yes yours is a drive by wire or TAC (throttle actuator control) Throttle body assembly, but with that you do also have a Accelerator Pedal Position Sensor (gas pedal) that has a TPS on it that tells the computer how much you are depressing the throttle pedal…
I have the best possible news. I’m glad I had a hunch and I’m glad you guys pushed me toward it. I limped it home then used another vehicle to run to walmart to grab one of those scan tools. Came back and read the codes.
Every possible DTC under the sun for throttle control circuit high input/open came up. I figured this sounds a lot like a broken wire or something has to be disconnected. I looked behind the throttle body where the harness plugs into the throttle position sensor and barely touched it, it fell right out. I plugged it back in firmly and it ran beautifully (about like it did at least before this particular event). Reduced engine power mode is off but the service traction control/stability control was still on. I cleared the codes and away those went as well. I drove it around my block but I haven’t taken it out on the road yet. It’s almost comical how much this vehicle felt like it was about to explode from an unplugged harness.
There was one code that I was curious about that seems new and unrelated to this. P0024 Exhaust Camshaft Position Timing - Over Advanced (Bank 2)
That code is likely for the camshaft position solenoid, which I think is a pretty straightforward repair. These also had big issues with the timing chain stretching, but that normally gives a camshaft or crankshaft correlation error code.
And that’s why we said multiple times to read the codes and go from there… lol
Great news, glad you found it…
On anything with a check light on, unless you open the hood and the part falls out on the floor in front of you, check the codes 1st… That is what the check engine light s for, to tell you that the computer sees something wrong (yes it is more complicated than that lol)
Even if the light is not on it can picking up pending and or history codes that might help as well…
I also tell anyone even if you know why your check engine light is on and it does not effect the operation of the vehicle to fix the issue anyway, because you have hundreds if not thousands of reasons for the light to come on but only ONE light, and if you don’t keep it off then you might not know if something else is going or about to go wrong that could be way more serious…
Very good point. I already got a purge valve on the way. Of course it’s not going to help with the trans problems but it’s one less problem and I won’t have problems starting the engine after refueling.
Put the new purge valve on earlier, slightly different part so it required me to remove the “adapter” that was attached to the manifold. This one bolts directly into the intake to where the old one has a metal bracket. There seems to be some sort of unsightly gap between the valve and the intake but it probably doesn’t matter because the nipple looks like it’s in far enough. I put a dab of oil on the oring before inserting it. I started the engine and put my finger over the inlet and this time no more vacuum. Seems like a fix to me, although the evap monitor hasn’t cleared yet even after a couple drive cycles. Haven’t refueld yet but when I do should be no issues. I heard a clicking/ticking noise when it was running and put my hand on it to verify it’s coming from the part. It is but the last one did that as well so I assume that’s normal.
I focus on 05-08 3.4 equinoxes. I see 2010+ equinoxes now and of course acadias and traverses. I really dont want to work on a 3.6. They look nice. But are disposable.
Saw a traverse with 1 yr old motor installed and it has timing chain issues again. Nope.
