Idle Air Control

Asked by Apr 13, 2017 at 09:47 PM about the 1999 GMC Sierra 1500 SLE Extended Cab SB

Question type: Maintenance & Repair

I thought my IAC was messing up so I tried to reset
it. So I unplugged the electrical connection turned
my truck on the replugged it. Now its worse than
before. What did I do wrong? Some one help

1 Answer

77,985

Sounds like you "taught" the computer a new closed position for the IAC. Not sure if this will work, but it's worth a try. Unplug the IAC and, using a scan tool, clear the computer. Turn off the ignition then unplug the scan tool. Plug the IAC back in and then start the engine. I've never heard of this happening with the IAC but that's the procedure for resetting the EGR valve. So it may work for the IAC too. BTW an EGR valve that's sticking open can cause poor idling, stalling, and hard/no starting. HTH. -Jim

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