2003 GMC Yukon Denali xl – Stability System Disabled, Reduce Engine Power
 

My 2003 Yukon Denali xl finally gave up on my way home from work. I got the Check Engine and Traction Control Alarms. The Console display was giving the following readouts. Stability System Disabled…… Reduce Engine Power…. Then I was stuck to 15 to 20 miles per hour all the way home. I got home and checked the codes.

Code List:
1. P0171 Fuel System Bank 1
2. P0174 Fuel System Bank 2
3. P0102 Mass Air Flow
4. P1514 MAPP or Mass Air Flow
5. P1516 Throttle Actuator Control
6. P0120 Throttle Position Pedal Sensor

I replaced the following parts:
1. Mass Air Flow Sensor
2. Throttle Position Sensor
3. Throttle Position Sensor Plug & 12″ of Cable
4. New Battery
5. Relocated the Black wire ground behind the engine and landed it again.
6. Checked all other grounds. – They look good.
7. Pedal Position Sensor
8. Checked all fuses in the fuse control box in the engine compartment.
9. Added new air filter
10. Added fuel treatment.

Codes Remaining:
1. P1125 Pedal Position Sensor
2. P0120 Throttle Position Pedal Sensor

Other Things I’ve done:
1. Gave the computer a hard reset by disconnecting the battery and the holding the +/- leads together.
2. Performed an engine idle retrain.

The Reduce Engine Power and Stability System Disabled read-out still comes in right away when I start the engine still. The idle was really high around 1000 but now it’s down around 600 to 700.

First, let me say I have been a GM man for life. Last truck, a 2000 Chevy Silverado had 310k on it where someone hit me from behind destroying it. So....I now have two GM products in the family. One is a 2009 GMC Sierra (99k Miles) and the other is a 2009 Chevy Tahoe (200k miles). Both of these pieces of garbage have stabiltrac lights going off, door locks jumping up and down, light flickering, gauges clusters going nuts,etc. when you log onto any of these forums, you see tons of folks on here complaining about this stupid system. Tonight, it temporarily stranded my wife and three year old while I was across the country on business. GM refuses to recall these vehicles and acknowledge the problem. Recently Ford manned up immediately and recalled 1.5 million F-150 trucks. Not only did they not take a bailout, apparently they specialize in doing the right thing. I can tell you one thing, I have bought my last GM.

Recalls are based on safety concerns...

Generally,

Both of these pieces of garbage have stabiltrac lights going off, door locks jumping up and down, light flickering, gauges clusters going nuts,etc. when you log onto any of these forums, you see tons of folks on here complaining about this stupid system.

these are not safety concerns......more than likely wiring concerns......and when you have a system, that is basically controlled by a BCM, your modules and your wiring/connections, have to be top quality.....something I think GM has dropped the ball on.....especially the wiring.....

As for your problem, about the only thing left that you didn't replace was the PPS, or check the wiring/connection to it...

Garbage
 

agreed on the GM wiring drop. And a safety issue is a legal question that they will hide behind. A vehicle that powers down to 20 mph on the highway unexpectedly is a safety issue IMO. A vehicle that causes the airbag light to go off and on...safety. I vehicle that won't let you out because it locks the doors. Safety