2003 Chevy Silverado 2003 Chevy Silverado SES code

FRENIMY

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2003 CHEVROLET SILVERADO

Engine Performance problem
2003 Chevy Silverado V8 Two Wheel Drive Automatic

I have a 2003 Silverado 1500 5.3l Auto 98k I have had a low idle around 500 sometimes stumbling around 350-400. When I come to a stop the engine sometimes stalls and when I make a turn at an idle it will stall. I go the SES codes which are P0120, P0220, P0446, P0156, P1516, P1518, P2135. The SES light came on a couple days ago but the low idle has been happening before then. The low idle did get worse once the SES light came on. No recent work done. Truck has K&N cold air intake and flowmaster cat back exhaust. What should my first course of action be to fix this problem?

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PEAR69

MECHANIC
1,482 POSTS

There are issues with loose grounds that will cause your problem. Tighten and check grounds G103 - located behind the passengers side cylinder head (just below the head itself) and attatched directly to the block with a 13mm headed bolt - and G104 - located behind the drivers side head and connected directly to the head but is very difficult to reach. Another ground to check is G110 - located on the outter drivers side fram rail.
Also, make sure the connection at the TAC (Throttle Air Control) module is good. Your issue sounds like a dirty or loose ground. Once you check all the possible causes listed -- have the SES light reset by clearing the trouble codes. Autozone or a place like that will do this for free. Let us know how you make out.

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Monday, June 8th, 2009 AT 12:52 AM

FRENIMY

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Well I tried the grounds and checked the TAC connection. Tat didn't seem to change anything. Just a little more info a few weeks ago cleaned the motor and accidentally got water in the plug connection for the TAC when I tried to run the truck it wouldn't stay running and control panel said Engine Power decreased. I blew out the connection with compressed air and put it back together. Is it possible I shorted something out or need to have something re calibrated from that?

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Tuesday, June 9th, 2009 AT 5:45 AM

PEAR69

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Yes.

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Tuesday, June 9th, 2009 AT 10:46 AM

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So what should I check and how can I do it. Is this something a repair shop has to do or only the dealer?

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Tuesday, June 9th, 2009 AT 1:19 PM

PEAR69

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You should have the ECU scanned with a dealers scan tool or equivalent scann tool. This will tell you where to look for the problem. Spraying water on any electronicaly controlled engine is a big no no. The TAC may be the problem, but proper diagnostic testing - with the proper scan tool - will save you money. All of the trouble codes point to a bad ground but an advanced scan tool will tell you for sure.