Last post on Dec 14, 2013 at 5:39 AM
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Chevrolet Impala, Auto Repair, Electrical, Fuel System, Sedan
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#251 of 491 Reduced Engine Power/Service Traction Control
Jan 22, 2013 (11:15 pm)
I was driving my 2009 Chevy Impala on the highway in a snowstorm and received the dreaded Service Traction Control/Reduced Engine Power messages and my car went from approximately 45 mph down to 20 mph and sounded like it was about to kick the bucket. I logged on here and started freaking out seeing people had spent $$$$$ to fix it, My father contacted a family friend who is a GM certified Mechanic and explained the problem... he said its pretty common. Anyways he told him to look at the "Drive by wire" wires going into the Throttle body, sure enough one of the wires was pulled loose from the plug not getting a solid contact and causing a short. With the car running (like garbage on reduced engine power) he pushed this loose wire back into its plug and magically the car immediately began to run like normal. All that's required is to buy a new "throttle body wire harness" which runs for 80$ on car parts discount websites, or trim back the wire insulation and solder the connection back in place. Seems to me from the fixes people posted its either the gas pedal or this wiring harness. To those who have tried the gas pedal replacement and continue to have problems check this wire harness that plugs into the throttle body. Here's a video from Youtube, I know this is a pickup truck but its the same issue, same wire harness, and in the same location under the hood of the Impala.
Loose Throttle Body Harness Wire Fix
#252 of 491 Re: Reduced Engine Power/Service Traction Control [trumble09]
Jan 23, 2013 (4:47 pm)
I have a 2009 Impala with same symptoms and after reading pages and pages of people having this same problem I am amazed. This obviously is an issue that should not be happening at this early age of my vehicle.
This is my last Chevy, too.
Jan 23, 2013 (5:18 pm)
The sad part is I have been dealing with the customes service (like I was asked to) and I have gotten NO WHERE! Trumble09.. my car says "starter disabled service throttle" before I get the "engine powee reduced" message. The car completely dies. I have to get out and take the terminal off to restart it. GMs advise to me was take it to a GM mechanic. The last GM mechanic that worked on my car somehow managed to put antifreeze in the transmission fluid.. I have 2 kids and I'm in college, I don't have the time or money to pay them to tell me they can't figure it out. I absolutely love this car when it's running but after all of this I will NEVER buy another Chevrolet.
#254 of 491 Re: Impala SS [kdh12389]
Jan 23, 2013 (7:23 pm)
Hey sorry I forgot to include that my car also displayed "service throttle starter disabled"after I turned my car off when it had been running rough. Ill take a picture of the wire harness and post pictures on where to find it. Give me an hour or so I'm replying from my phone at work. All in all its a p!ss poor design that's prone to failure. Before paying for a gas pedal try this throttle body wire harness as it may be the culprit.
#255 of 491 Re: Impala SS [kdh12389]
Jan 23, 2013 (9:22 pm)
Throttle Body wire harness pictures:
So this is the establishing shot, once you have popped the hood this is what it should look like more or less, pardon the dirt and sand its wintertime here, also pardon the picture quality its currently -4 degrees fahrenheit with a windchill making it -7.
This red circle is the area you're going to be concerned with, you can leave the valve cover on if you like. if you wanna take it off it involves unscrewing the oil cap and removing the oil cap fill neck and giving the plastic a tug. Instructions can be found on google
This next picture is of the drivers side front portion of the engine, the bunch of wires circled in red are the throttle body wire harness, Grip these wires in your hand and push them towards the plug and any loose connection that may be present will re-establish and either your motor will be back to running like normal or else this isn't the problem... but this is a good check to do before you go to the dealer and throw money at them to try to fix your car, if it's not this bunch of wires chances are its either the throttle body itself, or the APPS sensor in the gas pedal
Harness close up
Hopefully this helps some people, if your car is still running like garbage after having the dealer replace the throttle body and gas pedal check this bunch of wires because this wire harness is not often replaced when the throttle body is serviced.
#256 of 491 Re: Reduced Engine Power/Service Traction Control [jfudge]
Jan 23, 2013 (9:39 pm)
Yeah if your problem is caused by the exact same thing then Chevy needs to re-evaluate their wire/plug design. I had an issue with the airbag wire harness under my passenger seat 2 weeks after I bought my car, took it to the dealer took them all of 5 minutes to diagnose and i was charged 60$ because wires and sensors weren't covered by warranty. they just shoved the wire towards the plug and called it good 'nuff. check my post below with the links to pictures on Flickr and see if it helps your car, my car the minute that wire got shoved back into place was night and day as far as running like it should and not in the reduced engine power mode. Also works if you try to start the car and get the "Service throttle, Starter Disabled" message
#257 of 491 Re: Impala SS [trumble09]
Jan 23, 2013 (10:29 pm)
Sorry KDH, forgot you have the SS, probably the LS4 motor, I found a picture of one and circled and arrowed to what I believe is the Throttle Body Harness, not positive though you may know more about where the throttle body is on your v8
Impala SS Wire Harness
#258 of 491 Re: Impala SS [trumble09]
Jan 24, 2013 (5:29 am)
Ive been dealing with this since my car was practically new; only in the winter. I had in in several times under the warranty and they did nothing. Its really cold now and this is getting dangerous. I saw this post and so I jiggled and pushed those wires. It drove like a charm for 30 minutes. Then it went bad. Usually I can stop and wait a while and then go futher. I have appointment with dealer because I complained that they never fixed it but now at over 10000 miles they will cerainly charge me no matter how much I complain. I was hoping I had fixed it myself. Im a woman and am my wits end with this. I mean I had it in under the warranty and extended warranty so many times. The pedal was replaced (by me) and they cleaned the throttle or something.
#259 of 491 Re: Impala SS [trumble09]
Jan 24, 2013 (6:55 am)
As soon as my husband watched the video you sent me a link of yesterday he went out and jiggled all the wires with no change. The only time my car doesnt shut off is when u have ur foot completely buried in the throttle. But as soon as u let out of it it dies. I just want someone to tell me what the problem is so i can fix it myself. Anymore ideas??
#260 of 491 Re: Reduced Engine Power/Service Traction Control [jfudge]
Jan 24, 2013 (6:58 am)
Do you already have a plan of action for getting this checked into, jfudge? Let us know if you decide to work with a dealership as we're available to assist in that process.
Sarah, GM Customer Service