[swindler]

My wife's Envoy has been sluggish off and on for a couple of weeks, push on the pedal and not get the power expected. Then, yesterday she started it and pushed the pedal to the floor and the engine did not rev at all. She put it in park, turned it off, restarted, and it seemed to work.

I did a scan and found the P1515 code, which indicts the Thottle Position Sensor. One thing I noticed when I was playing with the pedal is that when the vehicle is idling in park, I can put the pedal to the floor and only get about 2500-3000 RPM. So there's clearly a disconnect.

I immediately read all the forums here, and tried removing and cleaning the throttle body with intake cleaner. It didn't look bad, but easy and free. That didn't have an effect.

I replaced the fan clutch a couple of years ago with supposedly the "new and improved" fan clutch, so that is not likely it.

So I spurged on a TPS, which unfortunately is built into the throttle body. I still can only get 2500-3000 RPM max.

I see there's a sensor at the pedal. I believe it's about $115 for the pedal/sensor assembly. That's probably next on my list.

But I'd like opinions as to whether it could be something else. I've not seen any other codes thrown (lately, anyway). It doesn't even throw the P1515 code very often. (I think it must have been that time where it did not rev at all.) But I'm concerned I'm chasing the wrong problem, as I've read that P1515 is usually accompanied with other codes.

Am I on the right track? Or should I look elsewhere? Opinions?

 

[WOOLUF1952]

The RPM's are limited in park and neutral, but thought it was higher than 3000. When you drive does it go higher than 3000?

 

[swindler]

The RPM's are limited in park and neutral, but thought it was higher than 3000. When you drive does it go higher than 3000?

Really? The RPMs are limited? My two non-GM vehicles will go to redline (or past) in park. I would not have thought the RPMs were limited. If someone could confirm that 2500-3000 is normal (floored in park), that would be helpful.

I have not driven the truck out of the driveway since I put on the new throttle body. I just checked the RPMs in park and thought I didn't affect the issue. I since took the new part out and put the old one back in. I will put the new part in once again (*sigh*) and try it for a few days to see how the vehicle drives. (I think I could do it blindfolded by now.) It appears I have 10 days to return the part (minus 15%).

 

[flyingfischer5]

Yes gm put a limiter on it in park.

If i was to floor mine in park it will climb fast to about 2500 and very slowly work it's way up to about 3500.

 

[swindler]

I know I posted this issue a couple of years ago, but I was looking through the site, found my post, and saw that I never wrapped it up with word of the ultimate root cause.

I had assumed after much troubleshooting that the issue had to be the fan clutch again. However, this time when I took it out I had noted that the exposed wires, (right before it enters the fan clutch assy), had been rubbing against the plastic mount and the jackets were worn through. In short, I had a short. This has been documented as an issue with some fan clutches, that the protective sleeving for the wires does not extend far enough to protect it from this rubbing. I replaced the fan clutch anyway and all was well.

Curiously, about six months ago I started seeing this same issue again - albeit without the engine code. But the fan clutch was behaving much the same. This time I opened it up and found that the connector for the fan clutch that's positioned on the fan shroud had come loose. I probably didn't seat it well enough 1.5 years prior. This time I put the same fan clutch back in and it's run fine since.

 

[mike17931793]

Hi Swindler. This is about your post with the P1515 code. Hopefully you will get an email about this post and be able to answer a question for me. I know it has been a long time ago since you wrote about your Trailblazer but I am having a similar problem; P1515 alone.. Replaced both the throttle body and the gas pedal already. I do notice another issue that might be related (because of what you wrote here). Once the engine is warmed up (217 deg F I believe), the AC compressor shuts off. I also had a code for too cold of engine temp at the same time originally, but I replaced the thermostat and it has not returned, but P1515 is relentless. I guess what I am asking if you are 100% sure that fixing the issue with the fan clutch resolved the P1515 error code as this code belongs to the "fly by wire" throttle system?

Thanks,

Mike