04 I5 reduce power light with CEL - Chevy Colorado & GMC Canyon
 
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post #1 of 14 (permalink) Old 01-15-2017, 04:57 PM Thread Starter
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04 I5 reduce power light with CEL

today my truck would not start. it would crank but not fire off. so I pulled the fuel pump fuse to check it ( it was good) then the truck started and the reduce power message light came on along with the check engine light. had a relative come with a Snap On scan tool, and plugged it in and got a ignition switch fault and a TAC fault. he didn't bring his fuel pressure gauge. would a bad ignition switch cause all this? when it would start it acted like it was out of fuel hence why I checked the fuse. any help

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post #2 of 14 (permalink) Old 01-15-2017, 07:39 PM
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Got the fault code numbers?

TAC fault code could be from a dirty throttle body and the butterfly in the throttle body is not moving freely, also check for loose or corroded wires where the harness connects to the throttle body.

But since you may have a bad ignition switch I would start to troubleshoot that problem first

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post #3 of 14 (permalink) Old 01-15-2017, 07:52 PM Thread Starter
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what causes it to go into limp mode?

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post #4 of 14 (permalink) Old 01-15-2017, 09:40 PM
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It is an electric throttle body, or drive by wire as some call it. Voltage signals control the opening and closing of the butterfly or throttle blade as some call it. If the throttle body is so dirty that the blade can't move properly it will throw a code and go into reduced power mode or if that signal is interrupted by a broken, loose or corroded wires it will also throw that code and go into reduced mode... common problem on a lot of GM vehicles that are drive by wire.

Also check for corrosion and loose or broken wires in the electrical ground points in the engine bay

2011 Colorado CC Z71 2LT 4X4 3.7L with a few mods

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post #5 of 14 (permalink) Old 01-15-2017, 09:43 PM Thread Starter
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Thanks

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post #6 of 14 (permalink) Old 01-15-2017, 10:03 PM Thread Starter
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What's strange I cleared the codes a few times with no change. So I guess something did fail

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post #7 of 14 (permalink) Old 01-15-2017, 10:14 PM
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Where you able to start it?

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post #8 of 14 (permalink) Old 01-15-2017, 10:24 PM Thread Starter
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Yes it would only run on limp mode

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post #9 of 14 (permalink) Old 01-15-2017, 10:49 PM
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Is the code P1516? If so just Google that code and reduced power chevy... plenty of info

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post #10 of 14 (permalink) Old 01-15-2017, 11:03 PM
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Also check and test the battery and make sure it is good... low voltage or if voltage drops too low during the cranking cycle can cause this code and reduced power mode as well

2011 Colorado CC Z71 2LT 4X4 3.7L with a few mods

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post #11 of 14 (permalink) Old 01-15-2017, 11:12 PM Thread Starter
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Battery is new as of two weeks ago and has shown no signs of being bad. Will look into all of this

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1994 Corvette base coupe
2006 Chevy Malibu (wife's)
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post #12 of 14 (permalink) Old 01-17-2017, 08:40 PM Thread Starter
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a little update. had it looked over and it was found the throttle body was bad or the sensor was bad, along with one of the two sensors on the gas pedal was bad. new parts are on order and should know more in a day or two

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post #13 of 14 (permalink) Old 01-19-2017, 06:17 PM Thread Starter
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a good update. found out a wire was bad between the ECM and the gas pedal. so fixed the short and now the truck runs and starts just fine.

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post #14 of 14 (permalink) Old 01-19-2017, 08:53 PM
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Awesome. Glad you found the problem

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