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P1518 Throttle Actuator Control Module and Rough Idle/Stalling

ramzzey13

New Member
Joined
Feb 24, 2018
Messages
1
Hi all, first and foremost thanks in advance to anyone giving me advice or assistance in helping me troubleshoot. You all are amazing!

I have a 2007 Chevy Avalanche 5.3L Flex Fuel LTZ. Bought it from my neighbor with 150,000 miles in January 2017. I've only put about 8,000 miles on it since then. I would only post if I really do not have a clue what to do next and believe me I have spent hours reading the already covered issues on this site. I just want to know if I am understanding all this correctly and if you guys agree with my "repair" ideas.

I have the "Reduced Engine Power" Message on the dash and recently I got my first check engine like which was the P1518 code Throttle Actuator Control (TAC from here on out) Module. I also have a very rough idle and sometimes when I come to a stop my truck just stalls. From all of my research I seem to have found that this probably is a electrical problem with either:
1. The gas pedal and the wires that route eventually to the engine bay.
2. The Electrical connector and wires going to the Throttle body itself.

After doing some research about 1.5 months ago I did this work and it totally seemed to fix the problem (but now its back again). I disconnected the battery, while working probably about 2.5 hours (and btw I bought a new AC Delco battery about 3 months ago). I proceeded to removed the mass air flow sensor (thing looked brand new) but I cleaned the harness connections (not the metal screen) where the harness plugged in with CRC QD Electrical Cleaner. Used a soft toothbrush and let it dry for at least a hour (overkill I know). I did the same thing with the electrical connector going to the throttle body (calling it TB from here on out). One issues I found that some people have is that some of the wires from the harness going to the TB get pulled out and this causes this problem. I checked all 8 (I think there were :cool: from the end of the harness back about 2 feet to make sure they all have connectivity using my volt meter. All of them had connection. I also gently cleaned out the TB while I was there. I then put it all back together and the truck had a perfect idle no codes or error messages. I was amazed that it was all working again so I just went with it and was happy.

A month down the road the problem came back sort of suddenly along with a fairly loud humming noise which seems to come from the front right. My driveway is on a slight angle so with the reduced engine power I can't even move it now. I just went out and started it a bit ago and the humming almost grinding noise seems to stay on constant!

Rather than get it towed to a Chevy dealership  ($75) and then having them use their computer/code reader to tell me what the issue is hopefully ($200) I was thinking about doing the following:
1.Replace gas pedal and electrical harness/wires that go with it.
2. Replace electrical harness that goes to TB.
3. If those don't solve it then replacing the TB as well.
Is this the right path or is there any other tests or advice anyone has? We have a third car which is a Chevy Aveo and coming from my Avalanche I cant stand driving that little go cart!

Couple other things I have done to my truck for what its worth. I do all the oil/fluid/filter changes. I replaced the fuel pump due to the top being completely rust out and I had a fuel smell with a AC delco replacement in May 2017 (I had no issues after the replacement). I have replaced the air bag 2 front sensors. I have replaced the little brake module (AC Delco part I think it was $12 bucks) probably around May 2017 because I was getting a Traction Control message and a service stabiltrack message on the dash. Since I replaced that I don't think I have gotten those errors again. I think that's all I have done (thankfully).

Please any advice you can give me I need to get this baby back on the road. Thanks for your time and have a great weekend! -Ramsey

 
See this post

http://www.chevyavalanchefanclub.com/cafcna/index.php?topic=129588.msg1930642#msg1930642
 
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