Power management problem

[turbojitsu]

What happened was the center console pops up saying power reduced with a big exclamation point over it, then a check engine light symbol, and then a safety mode with a exclamation point over it appears. The car starts to decelerate even while I give it gas. When I let off it starts to idle horribly. I turn the car off and restart it holding down the scroll well putting it into diagnostic mode. Then the car can be driven with out issue except for a check engine light on.

This problem happened to me about 2 weeks ago and I took it to a mechanic. They said it threw a couple codes something to do with the throttle body. They cleaned it and cleared the codes and now it happens again. I won't be able to get my hands on a scan tool to get the codes myself until late next week.

I'm just curious if any one else has experienced this problem and what the cause and solution was.?
Any help is much appreciated. Thanks in advance

[johnbell2]

sounds like a voltage/signal problem, not "my TB is dirty" problem (which IMHO is a damned snake oil "cure"... I've never had to clean a TB ever)...

what are your mods, if any? also, do you have any idea how old your battery is... while you're at it, pop the trunk open and make sure the battery cables are connected

[dru21281]

sounds like a voltage/signal problem, not "my TB is dirty" problem (which IMHO is a damned snake oil "cure"... I've never had to clean a TB ever)...

what are your mods, if any? also, do you have any idea how old your battery is... while you're at it, pop the trunk open and make sure the battery cables are connected

I would tend to agree that it is a voltage problem. OP when did this happen, normal driving, as soon as the car started, while idling etc.? It may be the battery as stated, alternator or wiring/loose connection. Also could be moisture somewhere.
I purchased a $12 BT wireless OBD2 reader from eBay and it works great on my Android. Mainly use Dash Command app, but Torq is also good. I can read/reset codes, monitor all Temps Inc. trans. I know it's not a great solution, but you can't go wrong for the price...

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[turbojitsu]

Completely stock. Original ac delco battery dash reads 11.8 with ignition on car off. 78% charge. Battery looks good no corrosion. It happened last week during normal driving and again today while on the express way.

[turbojitsu]

Honestly I'm not sure what they did my wife took the car in for me. I was thinking maybe throttle position sensor malfunction or another sensor going bad?

[AuuuSSSIII YA' LATA]

There's a few things it could be, def snag the code next time it happens, I can't remember if its a p2135 or p2138 code, gm has been having problems with the throttle position sensor on the 5.3's, accelerater pedal is another possible problem, it happens a lot on the impalas. Accelerator pedal position sensor. And yes a throttle body cleaning/relearn actually does fix problems in gm's. Witnessed it myself, the sensors behind the plate get caked up and don't read correctly. Rough idles, poor acceleration have all been fixed this way at my shop.

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[turbojitsu]

Got off of work early and able to get my hands on a scan tool. Code P1516 any ideas? Thanks again guys.

[Seattle09GT]

http://engine-codes.com/p1516_pontiac.html

P1516 Pontiac - Throttle Actuator Control Module Throttle Actuator Position Performance

Possible causes
- Faulty Throttle Actuator Control (TAC) module
- Throttle Actuator Control (TAC) module harness is open or shorted
- Throttle Actuator Control (TAC) module circuit poor electrical connection
- Check Throttle Actuator Control (TAC) module connector for water
- Binding or bent throttle plate-failed throttle body

All of these except the last one point to a failed sensor or voltage issue.

[AuuuSSSIII YA' LATA]

I'll check gm tomorrow, unfortunately they're having issues with all of their systems from these recalls. Gm's parts site literally crashed the other day due to all the orders for recall parts and what not. I'm curious now

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[turbojitsu]

Is the tac module the black plug or the device the black plug goes into that is connected to the throttle body. The harness doesn't look pinched or frayed anywhere I can trace it back. I couldn't get the plug off the throttle body to check the connections on the inside. Is there a trick to getting these weather pack plugs off. I slipped the grey clip back on it then tried pulling straight off.

[turbojitsu]

Okay I was able to pop the connector off and everything looks fine. No moisture or corrosion. Where can I get a TAC module and how hard is it to replace. Any one have a diagram of how to?

[turbojitsu]

I cant find just an actuator so I'm thinking I need to replace the throttle body all together. Looking at Rock Auto and they have 2 different AC Delco replacements one with and one without break point. I'm not sure what that is. Also there for 2009 1/2 model year How do I figure out when mine was made? If I replace the throttle body does the car have to relearn or be tuned again? What does that consist of?

[LDM]

If your throttle body has a gold throttle plate (LS3 style, GM part number 12605109), it is a 2009.5:

http://i843.photobucket.com/albums/zz352/lenmartin23/G8/ARP%20Bolt%20Kit/DSC_3378.jpg

If it has a silver throttle plate (LS2 style, GM part number 12570790), it is a 2009:

http://i295.photobucket.com/albums/mm132/charlesvanwormer/DSC04863.jpg

Also, besides the throttle plate differences notice that the actuators are shaped a little differently.

[turbojitsu]

Thanks LDM. I defenatley have the LS3 style gold throttle body. $200 dollar difference. By any chance do you know the gasket part number? I'll want to replace that as well.

[LDM]

12576549, though the gasket should be reusable.

[LDM]

Also, Amazon has the TB for cheaper than Rock Auto...

[AuuuSSSIII YA' LATA]

This is straight from gm's mouth....Not saying it'll fix it but it's worth a shot before buying a new tb.


#PIP4578A: SES Light Idle Surge And/Or Reduced Engine Power Mode With DTCs P0068 P0121 P0506 P0507 P1516 P2101 P2119 And/Or P2176 - Clean Throttle Body And Perform Idle Learn Reset - (Feb 9, 2010)
Subject: SES Light, Idle Surge, and/or Reduced Engine Power Mode with DTCs P0068, P0121, P0506, P0507, P1516, P2101, P2119, and/or P2176 - Clean Throttle Body and Perform Idle Learn Reset

Models: 2007 Buick Rainier
2007-2009 Cadillac CTS-V, Escalade
2008-2009 Chevrolet Colorado
2006-2009 Chevrolet Avalanche, Corvette, Express, Impala, Monte Carlo, Silverado, Suburban, Tahoe, Trail Blazer
2008-2009 GMC Canyon
2006-2009 GMC Envoy, Savana, Sierra, Yukon
2007-2008 Hummer H2
2008-2009 Hummer H3
2007-2008 Pontiac Grand Prix
2008-2009 Pontiac G8
2006-2009 Saab 97x
With a V8 Engine

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This PI was superseded to update model years and add information concerning idle surge, reduced engine power mode, and/or DTCs P0068, P0121, P1516, P2101, P2119, and/or P2176 that may be experienced on high mileage vehicles. Please discard PIP4578.


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The following diagnosis might be helpful if the vehicle exhibits the symptom(s) described in this PI.

Condition/Concern:As carbon builds up in the throttle body of a high mileage vehicle, the ECM/PCM learns to compensate by increasing the throttle plate angle.

If enough carbon builds up, an idle surge, deceleration surge, tip-in hesitation, reduced engine power mode, and/or DTCs P0068, P0121, P1516, P2101, P2119, and/or P2176 may be experienced on high mileage vehicles.

If the throttle body is cleaned without performing an "idle learn reset/reset idle learn" with the Tech 2, the ECM/PCM may continue to compensate for previous carbon build up, causing it to return with a similar concern as well as DTCs P0121, P0506, and/or P0507.

In a similar fashion, if the ECM/PCM of a high mileage vehicle is replaced and/or reprogrammed without performing the Throttle/Idle Learn outlined in SI, the ECM/PCM may no longer compensate for existing carbon build up in the throttle body, causing it to return with a similar concern as well as DTCs P0121, P0506, and/or P0507.

Recommendation/Instructions:If SI diagnosis does not isolate the cause of this concern, inspect the throttle body bore and plate for obvious carbon build up.

If carbon is present, follow the Throttle Body Cleaning Procedure in SI to clean the throttle body.

After ensuring that the throttle body bore and plate are clean, perform an "idle learn reset/reset idle learn" with the Tech 2 and re-evaluate the concern.

Notice: Depending on the vehicle you are working on, the "idle learn reset/reset idle learn" is normally found on the Tech 2 ECM menu for Module Set Up or Special Functions/TAC System.

Please follow this diagnostic or repair process thoroughly and complete each step. If the condition exhibited is resolved without completing every step, the remaining steps do not need to be performed.

[shawny125]

Did you ever fix your problem and what was the culprit

[turbojitsu]

Replaced the throttle body. Problem solved. I tried cleaning it but it wouldn't help for very long.

[gardnertroy]

Also check your mass airflow sensor. I've had the same dtc set a couple of times when I blew the MAF out. Blown out
From no2 backfire