P1515 code SES and REP lights

tk_427

Original poster
Member
Mar 13, 2012
12
Omaha
I have a 2002 Trailblazer vortec v-6 and 151k. taking a little drive in the neighborhood on saturday SES and REP lights came on, limped home (only 2 blocks away) and hooked up the code reader. P1515, googled it, and found an article about throttle body cleaning. I had cleaned it a couple of years ago, so I knew it was probably dirty and it is a simple process anyway. I put everything back together, and ran my errands with no lights what-so-ever.

Easter Sunday...driving to easter dinner 90 miles away, cruising at 75mph when a semi that was weaving back and forth in his lane but me over the edge and I felt the need to just get around him as fast as I can. stepped on the gas, vehicle started to accelerate, rpms went up for extra power, then...SES and REP lights. slowed down, pulled over turned off vehicle for a minute or 2 and restarted. SES light, but everything else was fine. Continued the drive, read code, P1515. Cleared the code and drove back home 5 hours later. Accelerated fine, no lights everything a-ok.

MY QUESTION...Where do i start to diagnose? I know that I should probably check for wire fray as this seems like a culprit. Already cleaned the throttle body, however I did notice when I had it out that there was a rattling noise coming from the sensor housing like there was something broken off and rattling around inside. When I opened and closed the butterfly valve it kind of made a little bit of a grinding noise like un-greased ball bearings. Also when cleaning the butterfly valve, it got stuck in the open position when spraying with the B-12 Chemtool cleaner. I kind of wiggled the valve a little bit and it finally released and shut. Could it be that the throttle body needs to be replaced? I have never worked on one, other that the previous cleaning a few years back, so I'm not sure what would be considered a "normal" sound would be when opening and closing the valve.

I'm kind of ruling out the wiring as my fan clutch was replaced several years ago but I am not ruling it out.

Feedback is much appreciated! :thumbsup:
 

The_Roadie

Lifetime VIP Donor
Member
Nov 19, 2011
9,957
Portland, OR
It should sound very smooth when you open the butterfly by hand. I'd schedule a replacement. Mechanical noises or a restriction of movement is very bad.
 

tk_427

Original poster
Member
Mar 13, 2012
12
Omaha
Thank you Roadie, I assumed as much. A replacement has been ordered and will hopefully remedy the problem.
 

tk_427

Original poster
Member
Mar 13, 2012
12
Omaha
Ok, so I took off the old throttle body and put the new one on and she started right up with no codes. Everything is running great.

Side story...after I got the TB home and parked in the driveway, I tried to start it up again and all I could hear was a grinding noise from under the hood for about 5 seconds when the key was in the on position. I turned the key and got out quick to hear where the sound was coming from, and it was the throttle. I removed the throttle body and it sounded like a maraca when I shook it. I took the cover off of the old throttle housing to try to figure out what might be in there, well, it is a miracle that the truck started at all, there were plastic gear teeth that broke off floating inside.

So, moral of the story...when you hear something rattling around a part, you should probably replace it! Oh, I bought a salvaged throttle body for $75 from Barker's Auto Salvage LLC in Axton, VA because they didn't have anything close to Omaha, NE for under $195.00. They also shipped it 2-day air from UPS for $15 more. They were very nice and easy to work with.
 

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